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Bartuzel MM, Consejo A, Stremplewski P, Sylwestrzak M, Szkulmowski M, Gorczynska I. In vivo identification of the retinal layer containing photopigments in OCT images through correlation with two-photon psychophysics. Sci Rep 2024; 14:15459. [PMID: 38965299 PMCID: PMC11224378 DOI: 10.1038/s41598-024-65234-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Accepted: 06/18/2024] [Indexed: 07/06/2024] Open
Abstract
Two-photon vision enables near-infrared light perception in humans. We investigate the possibility to utilize this phenomenon as an indicator of the location of the outer segments of photoreceptor cells in the OCT images. Since two-photon vision is independent on OCT imaging, it could provide external to OCT reference relative to which positions of retinal layers visible in OCT imaging could be measured. We show coincidence between OCT imaging of outer retinal layers and two-photon light perception. The experiment utilizes an intrinsic nonlinear process in the retina, two-photon absorption of light by visual photopigments, which triggers perception of near-infrared light. By shifting the focus of the imaging/stimulus beam, we link the peak efficiency of two-photon vision with the visibility of outer segments of photoreceptor cells, which can be seen as in vivo identification of a retinal layer containing visual photopigments in OCT images. Determination of the in-focus retinal layer is achieved by analysis of en face OCT image contrast. We discuss experimental methods and experimental factors that may influence two-photon light perception and the accuracy of the results. The limits of resolution are discussed in analysis of the one-photon and two-photon point spread functions.
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Affiliation(s)
- Maciej M Bartuzel
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Toruń, Poland.
| | - Alejandra Consejo
- Aragon Institute for Engineering Research (I3A), University of Zaragoza, Zaragoza, Spain
| | - Patrycjusz Stremplewski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Toruń, Poland
| | - Marcin Sylwestrzak
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Toruń, Poland
| | - Maciej Szkulmowski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Toruń, Poland
| | - Iwona Gorczynska
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Toruń, Poland
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Tan B, Li H, Zhuo Y, Han L, Mupparapu R, Nanni D, Barathi VA, Palanker D, Schmetterer L, Ling T. Light-evoked deformations in rod photoreceptors, pigment epithelium and subretinal space revealed by prolonged and multilayered optoretinography. Nat Commun 2024; 15:5156. [PMID: 38898002 PMCID: PMC11186825 DOI: 10.1038/s41467-024-49014-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 05/21/2024] [Indexed: 06/21/2024] Open
Abstract
Phototransduction involves changes in concentration of ions and other solutes within photoreceptors and in subretinal space, which affect osmotic pressure and the associated water flow. Corresponding expansion and contraction of cellular layers can be imaged using optoretinography (ORG), based on phase-resolved optical coherence tomography (OCT). Until now, ORG could reliably detect only photoisomerization and phototransduction in photoreceptors, primarily in cones under bright stimuli. Here, by employing a phase-restoring subpixel motion correction algorithm, which enables imaging of the nanometer-scale tissue dynamics during minute-long recordings, and unsupervised learning of spatiotemporal patterns, we discover optical signatures of the other retinal structures' response to visual stimuli. These include inner and outer segments of rod photoreceptors, retinal pigment epithelium, and subretinal space in general. The high sensitivity of our technique enables detection of the retinal responses to dim stimuli: down to 0.01% bleach level, corresponding to natural levels of scotopic illumination. We also demonstrate that with a single flash, the optoretinogram can map retinal responses across a 12° field of view, potentially replacing multifocal electroretinography. This technique expands the diagnostic capabilities and practical applicability of optoretinography, providing an alternative to electroretinography, while combining structural and functional retinal imaging in the same OCT machine.
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Affiliation(s)
- Bingyao Tan
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore
- SERI-NTU Advanced Ocular Engineering (STANCE) Program, Singapore, Singapore
| | - Huakun Li
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, Singapore, Singapore
| | - Yueming Zhuo
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, 94305, USA
- Department of Electrical Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Le Han
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore
- SERI-NTU Advanced Ocular Engineering (STANCE) Program, Singapore, Singapore
| | - Rajeshkumar Mupparapu
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore
- SERI-NTU Advanced Ocular Engineering (STANCE) Program, Singapore, Singapore
| | - Davide Nanni
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, Singapore, Singapore
| | - Veluchamy Amutha Barathi
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore
- Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore, Singapore
- Ophthalmology and Visual Sciences Academic Clinical Program (Eye ACP), Duke-NUS Medical School, Singapore, Singapore
| | - Daniel Palanker
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, 94305, USA.
- Department of Ophthalmology, Stanford University, Stanford, CA, 94305, USA.
| | - Leopold Schmetterer
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore.
- SERI-NTU Advanced Ocular Engineering (STANCE) Program, Singapore, Singapore.
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, Singapore, Singapore.
- Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore, Singapore.
- Ophthalmology and Visual Sciences Academic Clinical Program (Eye ACP), Duke-NUS Medical School, Singapore, Singapore.
- Department of Ophthalmology, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore.
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.
- Institute of Molecular and Clinical Ophthalmology, Basel, Switzerland.
| | - Tong Ling
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore.
- SERI-NTU Advanced Ocular Engineering (STANCE) Program, Singapore, Singapore.
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, Singapore, Singapore.
- School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, Singapore.
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Gaffney M, Connor TB, Cooper RF. Intensity-based optoretinography reveals sub-clinical deficits in cone function in retinitis pigmentosa. FRONTIERS IN OPHTHALMOLOGY 2024; 4:1373549. [PMID: 38984134 PMCID: PMC11182324 DOI: 10.3389/fopht.2024.1373549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Accepted: 05/15/2024] [Indexed: 07/11/2024]
Abstract
Introduction Clinical tools have been widely used in the diagnosis, description, and monitoring the progression of retinitis pigmentosa (RP); however, many of these methods have inherently low sensitivity and specificity, and significant photoreceptor disruption can occur before RP progression has clinically manifest. Adaptive optics scanning light ophthalmoscopy (AOSLO) has shown promise as a powerful tool for assessing photoreceptor disruption both structurally and functionally due to its increased resolution. Methods Here we assess photoreceptor structure and function at the cellular level through AOSLO by acquiring intensity based optoretinography (iORG) in 15 individuals with no reported retinal pathology and 7 individuals with a prior clinical diagnosis of RP. Photoreceptor structure was quantified by calculating cone nearest neighbor distance (NND) across different retinal eccentricities from the AOSLO images. Cone outer segment length was measured across different retinal eccentricities using optical coherence tomography (OCT) derived longitudinal reflectivity profiles (LRPs). Finally, iORG measures of photoreceptor function were compared to retinal sensitivity as measured using the macular integrity assessment (MAIA) microperimeter. Results Broadly, participants with RP exhibited increasing cone nearest neighbor distances and decreasing cone outer segment length as a function of retinal eccentricity, consistent with prior reports for both controls and individuals with RP. Nearly all individuals with RP had reduced iORG amplitudes for all retinal eccentricities when compared to the control cohort, and the reduction was greater in eccentricities further from the fovea. Comparing iORG amplitudes to MAIA retinal sensitivity, we found that the iORG was more sensitive to early changes in photoreceptor function whereas MAIA was more sensitive to later stages of disease. Discussion This highlights the utility of iORG as a method to detect sub-clinical deficits in cone function in all stages of disease progression and supports the future use of iORG for identifying cells that are candidates for cellular based therapies.
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Affiliation(s)
- Mina Gaffney
- Joint Department of Biomedical Engineering, Marquette University and the Medical College of Wisconsin, Milwaukee, WI, United States
| | - Thomas B. Connor
- Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Robert F. Cooper
- Joint Department of Biomedical Engineering, Marquette University and the Medical College of Wisconsin, Milwaukee, WI, United States
- Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, United States
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Xu P, Cooper RF, Jiang YY, Morgan JIW. Parafoveal cone function in choroideremia assessed with adaptive optics optoretinography. Sci Rep 2024; 14:8339. [PMID: 38594294 PMCID: PMC11004114 DOI: 10.1038/s41598-024-58059-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Accepted: 03/25/2024] [Indexed: 04/11/2024] Open
Abstract
Choroideremia (CHM) is an X-linked retinal degeneration leading to loss of the photoreceptors, retinal pigment epithelium (RPE), and choroid. Adaptive optics optoretinography is an emerging technique for noninvasive, objective assessment of photoreceptor function. Here, we investigate parafoveal cone function in CHM using adaptive optics optoretinography and compare with cone structure and clinical assessments of vision. Parafoveal cone mosaics of 10 CHM and four normal-sighted participants were imaged with an adaptive optics scanning light ophthalmoscope. While acquiring video sequences, a 2 s 550Δ10 nm, 450 nW/deg2 stimulus was presented. Videos were registered and the intensity of each cone in each frame was extracted, normalized, standardized, and aggregated to generate the population optoretinogram (ORG) over time. A gamma-pdf was fit to the ORG and the peak was extracted as ORG amplitude. CHM ORG amplitudes were compared to normal and were correlated with bound cone density, ellipsoid zone to RPE/Bruch's membrane (EZ-to-RPE/BrM) distance, and foveal sensitivity using Pearson correlation analysis. ORG amplitude was significantly reduced in CHM compared to normal (0.22 ± 0.15 vs. 1.34 ± 0.31). In addition, CHM ORG amplitude was positively correlated with cone density, EZ-to-RPE/BrM distance, and foveal sensitivity. Our results demonstrate promise for using ORG as a biomarker of photoreceptor function.
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Affiliation(s)
- Peiluo Xu
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Robert F Cooper
- Department of Ophthalmology, Joint Department of Biomedical Engineering, Medical College of Wisconsin, Marquette University and Medical College of Wisconsin, Milwaukee, WI, 53233, USA
| | - Yu You Jiang
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Center for Advanced Retinal and Ocular Therapeutics, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Jessica I W Morgan
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, 19104, USA.
- Center for Advanced Retinal and Ocular Therapeutics, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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Ding J, Kim TH, Ma G, Yao X. Intrinsic signal optoretinography of dark adaptation abnormality due to rod photoreceptor degeneration. Exp Biol Med (Maywood) 2024; 249:10024. [PMID: 38463390 PMCID: PMC10911128 DOI: 10.3389/ebm.2024.10024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Accepted: 01/04/2024] [Indexed: 03/12/2024] Open
Abstract
This research aims to investigate the potential of using intrinsic optical signal (IOS) optoretinography (ORG) to objectively detect dark adaptation (DA) abnormalities related to rod photoreceptor degeneration. Functional optical coherence tomography (OCT) was employed in both wild-type (WT) and retinal degeneration 10 (rd10) mice to conduct this assessment. Dynamic OCT measurements captured the changes in retinal thickness and reflectance from light-to-dark transition. Comparative analysis revealed significant IOS alterations within the outer retina. Specifically, a reduction in thickness from external limiting membrane (ELM) peak to retinal pigment epithelium (RPE) peak was observed (WT: 1.13 ± 0.69 µm, 30 min DA; rd10: 2.64 ± 0.86 µm, 30 min DA), as well as a decrease in the intensity of the inner segment ellipsoid zone (EZ) in 30 min DA compared to light adaptation (LA). The reduction of relative EZ intensity was notable in rd10 after 5 min DA and in WT after 15 min DA, with a distinguishable difference between rd10 and WT after 10 min DA. Furthermore, our findings indicated a significant decrease in the relative intensity of the hypo-reflective band between EZ and RPE in rd10 retinas during DA, which primarily corresponds to the outer segment (OS) region. In conclusion, the observed DA-IOS abnormalities, including changes in ELM-RPE thickness, EZ, and OS intensity, hold promise as differentiators between WT and rd10 mice before noticeable morphological abnormalities occur. These findings suggest the potential of this non-invasive imaging technique for the early detection of dysfunction in retinal photoreceptors.
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Affiliation(s)
- Jie Ding
- Department of Biomedical Engineering, University of Illinois Chicago, Chicago, IL, United States
| | - Tae-Hoon Kim
- Department of Biomedical Engineering, University of Illinois Chicago, Chicago, IL, United States
| | - Guangying Ma
- Department of Biomedical Engineering, University of Illinois Chicago, Chicago, IL, United States
| | - Xincheng Yao
- Department of Biomedical Engineering, University of Illinois Chicago, Chicago, IL, United States
- Department of Ophthalmology and Visual Sciences, University of Illinois Chicago, Chicago, IL, United States
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Zhang P, Vafaeva O, Dolf C, Ma Y, Wang G, Cho J, Chan HHL, Marsh-Armstrong N, Zawadzki RJ. Evaluating the performance of OCT in assessing static and potential dynamic properties of the retinal ganglion cells and nerve fiber bundles in the living mouse eye. BIOMEDICAL OPTICS EXPRESS 2023; 14:6422-6441. [PMID: 38420317 PMCID: PMC10898556 DOI: 10.1364/boe.504637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 11/08/2023] [Accepted: 11/11/2023] [Indexed: 03/02/2024]
Abstract
Glaucoma is a group of eye diseases characterized by the thinning of the retinal nerve fiber layer (RNFL), which is primarily caused by the progressive death of retinal ganglion cells (RGCs). Precise monitoring of these changes at a cellular resolution in living eyes is significant for glaucoma research. In this study, we aimed to assess the effectiveness of temporal speckle averaging optical coherence tomography (TSA-OCT) and dynamic OCT (dOCT) in examining the static and potential dynamic properties of RGCs and RNFL in living mouse eyes. We evaluated parameters such as RNFL thickness and possible dynamics, as well as compared the ganglion cell layer (GCL) soma density obtained from in vivo OCT, fluorescence scanning laser ophthalmoscopy (SLO), and ex vivo histology.
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Affiliation(s)
- Pengfei Zhang
- School of Optoelectronic Engineering and Instrumentation Science, Dalian University of Technology, Dalian, 116024, China
- UC Davis EyePod Small Animals Ocular Imaging Laboratory, University of California Davis, Davis, CA 95616, USA
| | - Olga Vafaeva
- Department of Ophthalmology & Vision Science, University of California Davis Eye Center, 4860 Y Street, Suite 2400, Sacramento, CA 95817, USA
| | - Christian Dolf
- Department of Ophthalmology & Vision Science, University of California Davis Eye Center, 4860 Y Street, Suite 2400, Sacramento, CA 95817, USA
| | - Yanhong Ma
- School of Optoelectronic Engineering and Instrumentation Science, Dalian University of Technology, Dalian, 116024, China
| | - Guozhen Wang
- School of Optoelectronic Engineering and Instrumentation Science, Dalian University of Technology, Dalian, 116024, China
| | - Jessicca Cho
- UC Davis EyePod Small Animals Ocular Imaging Laboratory, University of California Davis, Davis, CA 95616, USA
| | - Henry Ho-Lung Chan
- Laboratory of Experimental Optometry (Neuroscience), School of Optometry, The Hong Kong Polytechnic University, Hong Kong, China
- Research Centre for SHARP Vision (RCSV), The Hong Kong Polytechnic University, Hong Kong, China
| | - Nicholas Marsh-Armstrong
- Department of Ophthalmology & Vision Science, University of California Davis Eye Center, 4860 Y Street, Suite 2400, Sacramento, CA 95817, USA
| | - Robert J Zawadzki
- UC Davis EyePod Small Animals Ocular Imaging Laboratory, University of California Davis, Davis, CA 95616, USA
- Center for Human Ocular Imaging Research (CHOIR), Dept. of Ophthalmology & Vision Science, University of California Davis, 4860 Y Street, Suite 2400, Sacramento, CA 95817, USA
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Abstract
The human retina is amenable to direct, noninvasive visualization using a wide array of imaging modalities. In the ∼140 years since the publication of the first image of the living human retina, there has been a continued evolution of retinal imaging technology. Advances in image acquisition and processing speed now allow real-time visualization of retinal structure, which has revolutionized the diagnosis and management of eye disease. Enormous advances have come in image resolution, with adaptive optics (AO)-based systems capable of imaging the retina with single-cell resolution. In addition, newer functional imaging techniques provide the ability to assess function with exquisite spatial and temporal resolution. These imaging advances have had an especially profound impact on the field of inherited retinal disease research. Here we will review some of the advances and applications of AO retinal imaging in patients with inherited retinal disease.
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Affiliation(s)
- Jacque L Duncan
- Department of Ophthalmology, University of California, San Francisco, California 94143-4081, USA
| | - Joseph Carroll
- Department of Ophthalmology & Visual Sciences, Medical College of Wisconsin Eye Institute, Milwaukee, Wisconsin 53226, USA
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Bell BA, Kaul C, Dunaief JL, Hollyfield JG, Bonilha VL. A comparison of optophysiological biomarkers of photoreceptor stress and phototoxicity in BALB/cJ, B6 (Cg)-Tyrc-2J/J, and C57Bl/6J mouse strains. FRONTIERS IN OPHTHALMOLOGY 2023; 3:1128311. [PMID: 38689597 PMCID: PMC11057998 DOI: 10.3389/fopht.2023.1128311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
Ophthalmic imaging instruments, including the confocal scanning laser ophthalmoscope and spectral-domain optical coherence tomography system, originally intended for revealing ocular microstructures in the human eye, have been deployed by vision researchers to evaluate the eyes of numerous small and large animal species for more than two decades. In this study, we have used these two instruments to obtain imaging data sequentially from the retinas of three prominent, widely used experimental mouse models to document changes induced by two contrasting vivarium lighting conditions. Mice studied include albino BALB/cJ and B6(Cg)-Tyrc-2J/J and pigmented C57Bl/6J. Mice were reared under dim light conditions until ~8 weeks of age where they underwent baseline imaging. Following, mice were returned to the dim vivarium or relocated to the top rack cage position in a standard vivarium. Mice were then followed for several months by ocular imaging to catalog the retinal dynamics as a function of long-term dim vs. elevated, standard vivarium lighting exposure levels. Upon exposure to elevated light levels, B6(Cg)-Tyrc-2J/J underwent similar changes as BALB/cJ in regard to photoreceptor outer segment shortening, photoreceptor layer proximal aspect hyperreflective changes, and the development of retinal infoldings and autofluorescent sub-retinal inflammatory monocyte infiltrate. Noteworthy, however, is that infoldings and infiltrate occurred at a slower rate of progression in B6(Cg)-Tyrc-2J/J vs. BALB/cJ. The photoreceptor outer nuclear layer thickness of BALB/cJ degenerated steadily following elevated light onset. In contrast, B6(Cg)-Tyrc-2J/J degeneration was unremarkable for many weeks before experiencing a noticeable change in the rate of degeneration that was concomitant with a plateau and decreasing trend in number of retinal infoldings and monocyte infiltrate. Pathological changes in C57Bl/6J mice were unremarkable for all imaging biomarkers assessed with exception to autofluorescent sub-retinal inflammatory monocyte infiltrate, which showed significant accumulation in dim vs. elevated light exposed mice following ~1 year of observation. These data were evaluated using Spearman's correlation and Predictive Power Score matrices to determine the best imaging optophysiological biomarkers for indicating vivarium light stress and light-induced photoreceptor degeneration. This study suggests that changes in proximal aspect hyperreflectivity, outer segment shortening, retinal infoldings and autofluorescent sub-retinal inflammatory monocyte infiltrate are excellent indicators of light stress and light-induced degeneration in albino B6(Cg)-Tyrc-2J/J and BALB/cJ mouse strains.
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Affiliation(s)
- Brent A. Bell
- Scheie Eye Institute and Department of Ophthalmology, University of Pennsylvania, Philadelphia, PA, United States
- Cole Eye Institute/Ophthalmic Research, Cleveland Clinic, Cleveland, OH, United States
| | - Charles Kaul
- Cole Eye Institute/Ophthalmic Research, Cleveland Clinic, Cleveland, OH, United States
| | - Joshua L. Dunaief
- Scheie Eye Institute and Department of Ophthalmology, University of Pennsylvania, Philadelphia, PA, United States
| | - Joe G. Hollyfield
- Cole Eye Institute/Ophthalmic Research, Cleveland Clinic, Cleveland, OH, United States
- Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH, United States
| | - Vera L. Bonilha
- Cole Eye Institute/Ophthalmic Research, Cleveland Clinic, Cleveland, OH, United States
- Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH, United States
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Vedula P, Fina ME, Bell BA, Nikonov SS, Kashina A, Dong DW. β -actin is essential for structural integrity and physiological function of the retina. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.27.534392. [PMID: 37034790 PMCID: PMC10081178 DOI: 10.1101/2023.03.27.534392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Lack of non-muscle β -actin gene (Actb) leads to early embryonic lethality in mice, however mice with β - to γ -actin replacement develop normally and show no detectable phenotypes at young age. Here we investigated the effect of this replacement in the retina. During aging, these mice have accelerated de-generation of retinal structure and function, including elongated microvilli and defective mitochondria of retinal pigment epithelium (RPE), abnormally bulging photoreceptor outer segments (OS) accompanied by reduced transducin concentration and light sensitivity, and accumulation of autofluorescent microglia cells in the subretinal space between RPE and OS. These defects are accompanied by changes in the F-actin binding of several key actin interacting partners, including ezrin, myosin, talin, and vinculin known to play central roles in modulating actin cytoskeleton and cell adhesion and mediating the phagocytosis of OS. Our data show that β -actin protein is essential for maintaining normal retinal structure and function.
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Zhang P, Wahl DJ, Mocci J, Miller EB, Bonora S, Sarunic MV, Zawadzki RJ. Adaptive optics scanning laser ophthalmoscopy and optical coherence tomography (AO-SLO-OCT) system for in vivo mouse retina imaging. BIOMEDICAL OPTICS EXPRESS 2023; 14:299-314. [PMID: 36698677 PMCID: PMC9841993 DOI: 10.1364/boe.473447] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 11/22/2022] [Accepted: 11/22/2022] [Indexed: 05/02/2023]
Abstract
Optical coherence tomography (OCT) and scanning laser ophthalmoscopy (SLO) are imaging technologies invented in the 1980s that have revolutionized the field of in vivo retinal diagnostics and are now commonly used in ophthalmology clinics as well as in vision science research. Adaptive optics (AO) technology enables high-fidelity correction of ocular aberrations, resulting in improved resolution and sensitivity for both SLO and OCT systems. The potential of gathering multi-modal cellular-resolution information in a single instrument is of great interest to the ophthalmic imaging community. Although similar instruments have been developed for imaging the human retina, developing such a system for mice will benefit basic science research and should help with further dissemination of AO technology. Here, we present our work integrating OCT into an existing mouse retinal AO-SLO system, resulting in a multi-modal AO-enhanced imaging system of the living mouse eye. The new system allows either independent or simultaneous data acquisition of AO-SLO and AO-OCT, depending on the requirements of specific scientific experiments. The system allows a data acquisition speed of 200 kHz A-scans/pixel rate for OCT and SLO, respectively. It offers ∼6 µm axial resolution for AO-OCT and a ∼1 µm lateral resolution for AO-SLO-OCT imaging.
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Affiliation(s)
- Pengfei Zhang
- School of Optoelectronic Engineering and Instrumentation Science, Dalian University of Technology, Dalian, China
- UC Davis EyePod Small Animals Ocular Imaging Laboratory, Department of Cell Biology and Human Anatomy, University of California Davis, Davis, CA 95616, USA
| | - Daniel J. Wahl
- Engineering Science, Simon Fraser University, Burnaby BC, V5A 1S6, Canada
| | - Jacopo Mocci
- Dynamic Optics srl, Piazza Zanellato 5, 35131, Padova, Italy
| | - Eric B. Miller
- Center for Neuroscience, University of California, Davis, CA 95616, USA
| | - Stefano Bonora
- CNR-Institute for Photonics and Nanotechnology, Via Trasea 7, 35131, Padova, Italy
| | - Marinko V. Sarunic
- Engineering Science, Simon Fraser University, Burnaby BC, V5A 1S6, Canada
- Medical Physics and Biomedical Engineering, University College London, United Kingdom
- Institute of Ophthalmology, University College London, United Kingdom
| | - Robert J. Zawadzki
- UC Davis EyePod Small Animals Ocular Imaging Laboratory, Department of Cell Biology and Human Anatomy, University of California Davis, Davis, CA 95616, USA
- UC Davis Eye Center, Dept. of Ophthalmology & Vision Science, University of California Davis, 4860 Y Street, Suite 2400, Sacramento, California 95817, USA
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11
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Pandiyan VP, Schleufer S, Slezak E, Fong J, Upadhyay R, Roorda A, Ng R, Sabesan R. Characterizing cone spectral classification by optoretinography. BIOMEDICAL OPTICS EXPRESS 2022; 13:6574-6594. [PMID: 36589563 PMCID: PMC9774847 DOI: 10.1364/boe.473608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 10/26/2022] [Accepted: 10/27/2022] [Indexed: 05/02/2023]
Abstract
Light propagation in photoreceptor outer segments is affected by photopigment absorption and the phototransduction amplification cascade. Photopigment absorption has been studied using retinal densitometry, while recently, optoretinography (ORG) has provided an avenue to probe changes in outer segment optical path length due to phototransduction. With adaptive optics (AO), both densitometry and ORG have been used for cone spectral classification based on the differential bleaching signatures of the three cone types. Here, we characterize cone classification by ORG, implemented in an AO line-scan optical coherence tomography (OCT), and compare it against densitometry. The cone mosaics of five color normal subjects were classified using ORG showing high probability (∼0.99), low error (<0.22%), high test-retest reliability (∼97%), and short imaging durations (< 1 hour). Of these, the cone spectral assignments in two subjects were compared against AO-scanning laser opthalmoscope densitometry. High agreement (mean: 91%) was observed between the two modalities in these two subjects, with measurements conducted 6-7 years apart. Overall, ORG benefits from higher sensitivity and dynamic range to probe cone photopigments compared to densitometry, and thus provides greater fidelity for cone spectral classification.
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Affiliation(s)
- Vimal Prabhu Pandiyan
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA, USA
| | - Sierra Schleufer
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA, USA
- Graduate Program in Neuroscience, University of Washington, Seattle, WA, USA
| | - Emily Slezak
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA, USA
| | - James Fong
- Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, CA, USA
| | - Rishi Upadhyay
- Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, CA, USA
| | - Austin Roorda
- Herbert Wertheim School of Optometry and Vision Science, University of California, Berkeley, Berkeley, CA, USA
| | - Ren Ng
- Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, CA, USA
| | - Ramkumar Sabesan
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA, USA
- Graduate Program in Neuroscience, University of Washington, Seattle, WA, USA
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12
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Warner RL, Brainard DH, Morgan JIW. Repeatability and reciprocity of the cone optoretinogram. BIOMEDICAL OPTICS EXPRESS 2022; 13:6561-6573. [PMID: 36589578 PMCID: PMC9774868 DOI: 10.1364/boe.471990] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 11/08/2022] [Accepted: 11/08/2022] [Indexed: 05/02/2023]
Abstract
Optoretinography has enabled noninvasive visualization of physiological changes in cone photoreceptors exposed to light. Understanding the cone optoretinogram in healthy subjects is essential for establishing it as a biomarker for cone function in disease. Here, we measure the population cone intensity optoretinogram in healthy adults, for multiple irradiance/duration combinations of visible stimuli with equal energy. We study the within and between session repeatability and reciprocity of the ORG in five healthy subjects. We find the cone optoretinogram exhibits equivalent amplitudes for equal-energy stimuli. We also find good within-subject repeatability, which allows us to show differences across the five subjects.
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Affiliation(s)
- R. L. Warner
- Scheie Eye Institute, Department of
Ophthalmology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - D. H. Brainard
- Psychology Department, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - J. I. W. Morgan
- Scheie Eye Institute, Department of
Ophthalmology, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Center for Advanced Retinal and Ocular
Therapeutics, University of Pennsylvania,
Philadelphia, PA, 19104, USA
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13
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Jiang X, Liu T, Pandiyan VP, Slezak E, Sabesan R. Coarse-scale optoretinography (CoORG) with extended field-of-view for normative characterization. BIOMEDICAL OPTICS EXPRESS 2022; 13:5989-6002. [PMID: 36733759 PMCID: PMC9872880 DOI: 10.1364/boe.473475] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 10/04/2022] [Accepted: 10/11/2022] [Indexed: 05/02/2023]
Abstract
Optoretinography (ORG) has the potential to be an effective biomarker for light-evoked retinal activity owing to its sensitive, objective, and precise localization of retinal function and dysfunction. Many ORG implementations have used adaptive optics (AO) to localize activity on a cellular scale. However, the use of AO restricts field-of-view (FOV) to the isoplanatic angle, necessitating the montaging of multiple regions-of-interest to cover an extended field. In addition, subjects with lens opacities, increased eye movements and decreased mobility pose challenges for effective AO operation. Here, we developed a coarse-scale ORG (CoORG) system without AO, which accommodates FOVs up to 5.5 deg. in a single acquisition. The system is based on a line-scan spectral domain OCT with volume rates of up to 32 Hz (16,000 B-frames per second). For acquiring ORGs, 5.5 deg. wide OCT volumes were recorded after dark adaptation and two different stimulus bleaches. The stimulus-evoked optical phase change was calculated from the reflections encasing the cone outer segments and its variation was assessed vs. eccentricity in 12 healthy subjects. The general behavior of ΔOPL vs. time mimicked published reports. High trial-to-trial repeatability was observed across subjects and with eccentricity. Comparison of ORG between CoORG and AO-OCT based ORG at 1.5°, 2.5°, and 3.5° eccentricity showed an excellent agreement in the same 2 subjects. The amplitude of the ORG response decreased with increasing eccentricity. The variation of ORG characteristics between subjects and versus eccentricity was well explained by the photon density of the stimulus on the retina and the outer segment length. Overall, the high repeatability and rapid acquisition over an extended field enabled the normative characterization of the cone ORG response in healthy eyes, and provides a promising avenue for translating ORG for widespread clinical application.
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Affiliation(s)
- Xiaoyun Jiang
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
| | - Teng Liu
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
| | - Vimal Prabhu Pandiyan
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
| | - Emily Slezak
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
| | - Ramkumar Sabesan
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
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14
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Human cone elongation responses can be explained by photoactivated cone opsin and membrane swelling and osmotic response to phosphate produced by RGS9-catalyzed GTPase. Proc Natl Acad Sci U S A 2022; 119:e2202485119. [PMID: 36122241 PMCID: PMC9522364 DOI: 10.1073/pnas.2202485119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Optical coherence tomography has established that human cone photoreceptor outer segments elongate in response to stimuli bleaching large fractions of their visual pigment. Elongation responses are completely described over their 200-fold bleaching range as the sum of two exponentially rising components differing 13-fold in time constants and 4-fold in light sensitivity. Bleaching measurements of individual cones with adaptive optics scanning laser ophthalmoscopy (SLO) suggest that component 2 arises from cone opsin and disk membrane swelling triggered by photoactivation. Application of a model of phototransduction suggests that component 1 corresponds to free phosphate generated by regulator of G-protein signaling 9 (RGS9)-catalyzed hydrolysis of guanosine triphosphate (GTP) in the α-subunit of G protein complexed with phosphodiesterase. Human cone outer segment (COS) length changes in response to stimuli bleaching up to 99% of L- and M-cone opsins were measured with high resolution, phase-resolved optical coherence tomography (OCT). Responses comprised a fast phase (∼5 ms), during which COSs shrink, and two slower phases (1.5 s), during which COSs elongate. The slower components saturated in amplitude (∼425 nm) and initial rate (∼3 nm ms−1) and are well described over the 200-fold bleaching range as the sum of two exponentially rising functions with time constants of 80 to 90 ms (component 1) and 1,000 to 1,250 ms (component 2). Measurements with adaptive optics reflection densitometry revealed component 2 to be linearly related to cone pigment bleaching, and the hypothesis is proposed that it arises from cone opsin and disk membrane swelling triggered by isomerization and rate-limited by chromophore hydrolysis and its reduction to membrane-localized all-trans retinol. The light sensitivity and kinetics of component 1 suggested that the underlying mechanism is an osmotic response to an amplified soluble by-product of phototransduction. The hypotheses that component 1 corresponds to G-protein subunits dissociating from the membrane, metabolites of cyclic guanosine monophosphate (cGMP) hydrolysis, or by-products of activated guanylate cyclase are rejected, while the hypothesis that it corresponds to phosphate produced by regulator of G-protein signaling 9 (RGS9)-catalyzed hydrolysis of guanosine triphosphate (GTP) in G protein–phosphodiesterase complexes was found to be consistent with the results. These results provide a basis for the assessment with optoretinography of phototransduction in individual cone photoreceptors in health and during disease progression and therapeutic interventions.
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15
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Gao S, Zeng Y, Li Y, Cohen ED, Berkowitz BA, Qian H. Fast and slow light-induced changes in murine outer retina optical coherence tomography: complementary high spatial resolution functional biomarkers. PNAS NEXUS 2022; 1:pgac208. [PMID: 36338188 PMCID: PMC9615127 DOI: 10.1093/pnasnexus/pgac208] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 09/21/2022] [Indexed: 11/18/2022]
Abstract
Fast (seconds) and slow (minutes to hours) optical coherence tomography (OCT) responses to light stimulation have been developed to probe outer retinal function with higher spatial resolution than the classical full-field electroretinogram (ERG). However, the relationships between functional information revealed by OCT and ERG are largely unexplored. In this study, we directly compared the fast and slow OCT responses with the ERG. Fast responses [i.e. the optoretinogram (ORG)] are dominated by reflectance changes in the outer segment (OS) and the inner segment ellipsoid zone (ISez). The ORG OS response has faster kinetics and a higher light sensitivity than the ISez response, and both differ significantly with ERG parameters. Sildenafil-inhibition of phototransduction reduced the ORG light sensitivity, suggesting a complete phototransduction pathway is needed for ORG responses. Slower OCT responses were dominated by light-induced changes in the external limiting membrane to retinal pigment epithelium (ELM-RPE) thickness and photoreceptor-tip hyporeflective band (HB) magnitudes, with the biggest changes occurring after prolonged light stimulation. Mice with high (129S6/ev) vs. low (C57BL/6 J) ATP(adenosine triphosphate) synthesis efficiency show similar fast ORG, but dissimilar slow OCT responses. We propose that the ORG reflects passive physiology, such as water movement from photoreceptors, in response to the photocurrent response (measurable by ERG), whereas the slow OCT responses measure mitochondria-driven physiology in the outer retina, such as dark-provoked water removal from the subretinal space.
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Affiliation(s)
- Shasha Gao
- Department of Ophthalmology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450001, China
- Visual Function Core, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yong Zeng
- Visual Function Core, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yichao Li
- Visual Function Core, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ethan D Cohen
- Division of Biomedical Physics, Office of Science and Engineering Labs, Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, MD 20993-0002, USA
| | - Bruce A Berkowitz
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI 48202, USA
| | - Haohua Qian
- Visual Function Core, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
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16
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Pfäffle C, Spahr H, Gercke K, Puyo L, Höhl S, Melenberg D, Miura Y, Hüttmann G, Hillmann D. Phase-Sensitive Measurements of Depth-Dependent Signal Transduction in the Inner Plexiform Layer. Front Med (Lausanne) 2022; 9:885187. [PMID: 35721092 PMCID: PMC9198552 DOI: 10.3389/fmed.2022.885187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Accepted: 05/10/2022] [Indexed: 12/01/2022] Open
Abstract
Non-invasive spatially resolved functional imaging in the human retina has recently attracted considerable attention. Particularly functional imaging of bipolar and ganglion cells could aid in studying neuronal activity in humans, including an investigation of processes of the central nervous system. Recently, we imaged the activity of the inner neuronal layers by measuring nanometer-size changes of the cells within the inner plexiform layer (IPL) using phase-sensitive optical coherence tomography (OCT). In the IPL, there are connections between the neuronal cells that are dedicated to the processing of different aspects of the visual information, such as edges in the image or temporal changes. Still, so far, it was not possible to assign functional changes to single cells or cell classes in living humans, which is essential for studying the vision process. One characteristic of signal processing in the IPL is that different aspects of the visual impression are only processed in specific sub-layers (strata). Here, we present an investigation of these functional signals for three different sub-layers in the IPL with the aim to separate different properties of the visual signal processing. Whereas the inner depth-layer, closest to the ganglion cells, exhibits an increase in the optical path length, the outer depth-layer, closest to the bipolar cell layer, exhibits a decrease in the optical path length. Additionally, we found that the central depth is sensitive to temporal changes, showing a maximum response at a stimulation frequency of around 12.5 Hz. The results demonstrate that the signals from different cell types can be distinguished by phase-sensitive OCT.
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Affiliation(s)
- Clara Pfäffle
- Institute of Biomedical Optic, University of Lübeck, Lübeck, Germany
| | - Hendrik Spahr
- Institute of Biomedical Optic, University of Lübeck, Lübeck, Germany
| | - Katharina Gercke
- Institute of Biomedical Optic, University of Lübeck, Lübeck, Germany
| | - Léo Puyo
- Institute of Biomedical Optic, University of Lübeck, Lübeck, Germany.,Medical Laser Center Lübeck GmbH, Lübeck, Germany
| | - Svea Höhl
- Institute of Biomedical Optic, University of Lübeck, Lübeck, Germany
| | - David Melenberg
- Institute of Biomedical Optic, University of Lübeck, Lübeck, Germany
| | - Yoko Miura
- Institute of Biomedical Optic, University of Lübeck, Lübeck, Germany.,Department of Ophthalmology, University of Lübeck, Lübeck, Germany
| | - Gereon Hüttmann
- Institute of Biomedical Optic, University of Lübeck, Lübeck, Germany.,Airway Research Center North, Member of the German Center for Lung Research, Grosshansdorf, Germany.,Center of Brain, Behavior and Metabolism (CBBM), University of Lübeck, Lübeck, Germany
| | - Dierck Hillmann
- Institute of Biomedical Optic, University of Lübeck, Lübeck, Germany.,Thorlabs GmbH, Lübeck, Germany.,Department of Physics, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
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17
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Kim TH, Ma G, Son T, Yao X. Functional Optical Coherence Tomography for Intrinsic Signal Optoretinography: Recent Developments and Deployment Challenges. Front Med (Lausanne) 2022; 9:864824. [PMID: 35445037 PMCID: PMC9013890 DOI: 10.3389/fmed.2022.864824] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 03/16/2022] [Indexed: 11/13/2022] Open
Abstract
Intrinsic optical signal (IOS) imaging of the retina, also termed as optoretinogram or optoretinography (ORG), promises a non-invasive method for the objective assessment of retinal function. By providing the unparalleled capability to differentiate individual retinal layers, functional optical coherence tomography (OCT) has been actively investigated for intrinsic signal ORG measurements. However, clinical deployment of functional OCT for quantitative ORG is still challenging due to the lack of a standardized imaging protocol and the complication of IOS sources and mechanisms. This article aims to summarize recent developments of functional OCT for ORG measurement, OCT intensity- and phase-based IOS processing. Technical challenges and perspectives of quantitative IOS analysis and ORG interpretations are discussed.
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Affiliation(s)
- Tae-Hoon Kim
- Richard and Loan Hill Department of Biomedical Engineering, University of Illinois at Chicago, Chicago, IL, United States
| | - Guangying Ma
- Richard and Loan Hill Department of Biomedical Engineering, University of Illinois at Chicago, Chicago, IL, United States
| | - Taeyoon Son
- Richard and Loan Hill Department of Biomedical Engineering, University of Illinois at Chicago, Chicago, IL, United States
| | - Xincheng Yao
- Richard and Loan Hill Department of Biomedical Engineering, University of Illinois at Chicago, Chicago, IL, United States
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL, United States
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18
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Tomczewski S, Węgrzyn P, Borycki D, Auksorius E, Wojtkowski M, Curatolo A. Light-adapted flicker optoretinograms captured with a spatio-temporal optical coherence-tomography (STOC-T) system. BIOMEDICAL OPTICS EXPRESS 2022; 13:2186-2201. [PMID: 35519256 PMCID: PMC9045926 DOI: 10.1364/boe.444567] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 02/20/2022] [Accepted: 02/23/2022] [Indexed: 06/14/2023]
Abstract
For many years electroretinography (ERG) has been used for obtaining information about the retinal physiological function. More recently, a new technique called optoretinography (ORG) has been developed. In one form of this technique, the physiological response of retinal photoreceptors to visible light, resulting in a nanometric photoreceptor optical path length change, is measured by phase-sensitive optical coherence tomography (OCT). To date, a limited number of studies with phase-based ORG measured the retinal response to a flickering light stimulation. In this work, we use a spatio-temporal optical coherence tomography (STOC-T) system to capture optoretinograms with a flickering stimulus over a 1.7 × 0.85 mm2 area of a light-adapted retina located between the fovea and the optic nerve. We show that we can detect statistically-significant differences in the photoreceptor optical path length (OPL) modulation amplitudes in response to different flicker frequencies and with better signal to noise ratios (SNRs) than for a dark-adapted eye. We also demonstrate the ability to spatially map such response to a patterned stimulus with light stripes flickering at different frequencies, highlighting the prospect of characterizing the spatially-resolved temporal-frequency response of the retina with ORG.
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Affiliation(s)
- Sławomir Tomczewski
- International Centre for Translational Eye Research, Skierniewicka 10A, 01-230, Warszawa, Poland
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warszawa, Poland
- Equal contributors
| | - Piotr Węgrzyn
- International Centre for Translational Eye Research, Skierniewicka 10A, 01-230, Warszawa, Poland
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warszawa, Poland
- Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warszawa, Poland
- Equal contributors
| | - Dawid Borycki
- International Centre for Translational Eye Research, Skierniewicka 10A, 01-230, Warszawa, Poland
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warszawa, Poland
| | - Egidijus Auksorius
- International Centre for Translational Eye Research, Skierniewicka 10A, 01-230, Warszawa, Poland
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warszawa, Poland
- Center for Physical Sciences and Technology (FTMC), Saulėtekio al. 3, LT-10257 Vilnius, Lithuania
| | - Maciej Wojtkowski
- International Centre for Translational Eye Research, Skierniewicka 10A, 01-230, Warszawa, Poland
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warszawa, Poland
| | - Andrea Curatolo
- International Centre for Translational Eye Research, Skierniewicka 10A, 01-230, Warszawa, Poland
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warszawa, Poland
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19
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Zhang L, Dong R, Zawadzki RJ, Zhang P. Volumetric data analysis enabled spatially resolved optoretinogram to measure the functional signals in the living retina. JOURNAL OF BIOPHOTONICS 2022; 15:e202100252. [PMID: 34817116 PMCID: PMC8901551 DOI: 10.1002/jbio.202100252] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Revised: 10/21/2021] [Accepted: 11/22/2021] [Indexed: 05/05/2023]
Abstract
Optoretinogram, a technique in which optical coherence tomography (OCT) is used to measure retinal functions in response to a visible light stimulus, can be a potentially useful tool to quantify retinal health alterations. Existing experimental studies on animals have focused on measuring the global retinal response by transversally averaging 3D data across the retina, which minimizes the spatial resolution of the signals, and limits the signal-to-noise ratio because only central B-scans are collected and analyzed. These problems were addressed in this study by collecting volumetric data to probe functional signals and developing an improved 3D registration approach to align such series-acquired OCT volumes. These data were then divided into small blocks and subject to a spatiotemporal analysis, whose results confirmed the spatial-dependence of functional signals. By further averaging, the overall measurement accuracies for the position and the scattering signals were estimated to be approximately 30 nm and 1.1 %, respectively. With improved accuracy, this method revealed certain novel functional signals that have not been previously reported. In conclusion, this work provides a powerful tool to monitor retinal local and global functional changes in aging, diseased, or treated rodent eyes.
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Affiliation(s)
- Lijie Zhang
- School of Optoelectronic Engineering and Instrumentation Science, Dalian University of Technology, 116024, China
| | - Rongyao Dong
- School of Optoelectronic Engineering and Instrumentation Science, Dalian University of Technology, 116024, China
| | - Robert J. Zawadzki
- UC Davis Eye-Pod Small Animals Ocular Imaging Laboratory, Department of Cell Biology and Human Anatomy, University of California Davis, Davis, California, 95616, United States
- UC Davis Eye Center, Department of Ophthalmology & Vision Science, University of California Davis, Sacramento, California, 95817, United States
| | - Pengfei Zhang
- School of Optoelectronic Engineering and Instrumentation Science, Dalian University of Technology, 116024, China
- UC Davis Eye-Pod Small Animals Ocular Imaging Laboratory, Department of Cell Biology and Human Anatomy, University of California Davis, Davis, California, 95616, United States
- Correspondence: Pengfei Zhang, Dalian University of Technology, 116024, China,
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20
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Kim TH, Ding J, Yao X. Intrinsic signal optoretinography of dark adaptation kinetics. Sci Rep 2022; 12:2475. [PMID: 35169239 PMCID: PMC8847457 DOI: 10.1038/s41598-022-06562-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 02/02/2022] [Indexed: 12/13/2022] Open
Abstract
Delayed dark adaptation due to impaired rod photoreceptor homeostasis has been reported as the earliest symptom of eye diseases such as age-related macular degeneration, diabetic retinopathy, and retinitis pigmentosa. Objective measurement of dark adaptation can facilitate early diagnosis to enable prompt intervention to prevent vision loss. However, there is a lack of noninvasive methods capable of spatiotemporal monitoring of photoreceptor changes during dark adaptation. Here we demonstrate functional optical coherence tomography (OCT) for in vivo intrinsic signal optoretinography (ORG) of dark adaptation kinetics in the C57BL/6J mouse retina. Functional OCT revealed a shortening of the outer retina, a rearrangement of the cone and rod photoreceptor interdigitation zone, and a reduction in intrinsic signal amplitude at the photoreceptor inner segment ellipsoid (ISe). A strong positive correlation between the outer retinal shortening and ISe intensity reduction was also confirmed. Functional OCT of dark adaptation kinetics promises an objective method for rapid ORG assessment of physiological integrity of retinal photoreceptors.
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Affiliation(s)
- Tae-Hoon Kim
- Department of Biomedical Engineering, University of Illinois at Chicago, Chicago, IL, 60607, USA
| | - Jie Ding
- Department of Biomedical Engineering, University of Illinois at Chicago, Chicago, IL, 60607, USA
| | - Xincheng Yao
- Department of Biomedical Engineering, University of Illinois at Chicago, Chicago, IL, 60607, USA.
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL, 60612, USA.
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21
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Affiliation(s)
- Austin Roorda
- Herbert Wertheim School of Optometry and Vision Science, University of California, Berkeley, CA 94720
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22
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Messner A, Aranha Dos Santos V, Stegmann H, Puchner S, Schmidl D, Leitgeb R, Schmetterer L, Werkmeister RM. Quantification of intrinsic optical signals in the outer human retina using optical coherence tomography. Ann N Y Acad Sci 2021; 1510:145-157. [PMID: 34893981 PMCID: PMC9299665 DOI: 10.1111/nyas.14721] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 09/03/2021] [Accepted: 10/20/2021] [Indexed: 01/10/2023]
Abstract
Intrinsic optical signals constitute a noninvasive biomarker promising the objective assessment of retinal photoreceptor function. We employed a commercial optical coherence tomography (OCT) system and an OCT signal model for evaluation of optical path length (OPL) changes in the temporal outer retina of five healthy subjects during light adaptation. Data were acquired at 30 time points, in ambient light and during long duration stimulation with white light, and analyzed, employing a signal model based on the sum of seven Gaussian curves corresponding to all relevant anatomical structures of the outer retina. During light stimulation, mean OPL between rod outer segment tips (ROST) and the retinal pigment epithelium (RPE) decreased by 21.4 ± 3.5%. Further, OPL between the external‐limiting membrane (ELM) and the RPE decreased by 5.2 ± 0.9% versus baseline, while OPL between ELM and ROST showed an initial decrease by 2.1 ± 1.6% versus baseline and, thereafter, increased by 2.8 ± 2.1% versus baseline. Thus, the presented approach allowed for assess to dynamic changes in the outer retina in response to light. The change in the subretinal space occurring in the context of light adaptation could be measured using a standard OCT platform and a dedicated signal model.
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Affiliation(s)
- Alina Messner
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.,Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Vienna, Austria
| | | | - Hannes Stegmann
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.,Christian Doppler Laboratory for Ocular and Dermal Effects of Thiomers, Medical University of Vienna, Vienna, Austria
| | - Stefan Puchner
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Doreen Schmidl
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Rainer Leitgeb
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Leopold Schmetterer
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.,Christian Doppler Laboratory for Ocular and Dermal Effects of Thiomers, Medical University of Vienna, Vienna, Austria.,Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.,Singapore Eye Research Institute, The Academia, Singapore.,SERI-NTU Advanced Ocular Engineering (STANCE) Program, Nanyang Technological University, Singapore.,School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore.,Ophthalmology and Visual Sciences Academic Clinical Program, Duke-NUS Medical School, Singapore.,Institute of Molecular and Clinical Ophthalmology, Basel, Switzerland
| | - René M Werkmeister
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.,Christian Doppler Laboratory for Ocular and Dermal Effects of Thiomers, Medical University of Vienna, Vienna, Austria
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23
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Kho AM, Srinivasan VJ. Proactive spectrometer matching for excess noise suppression in balanced visible light optical coherence tomography (OCT). OPTICS EXPRESS 2021; 29. [PMCID: PMC8970694 DOI: 10.1364/oe.439919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Supercontinuum sources for visible light spectral domain OCT (SDOCT) are noisy and often expensive. Balanced detection can reduce excess noise, but is rarely used in SDOCT. Here, we show that balanced detection can achieve effective excess noise cancellation across all depths if two linear array spectrometers are spectrally well-matched. We propose excess noise correlation matrices as tools to achieve such precise spectral matching. Using optomechanical adjustments, while monitoring noise correlations, we proactively match wavelength sampling of two different spectrometers to just a few picometers in wavelength, or 0.001% of the overall spectral range. We show that proactively-matched spectrometers can achieve an excess noise suppression of more than two orders-of-magnitude in balanced visible light OCT, outperforming simple retrospective software calibration of mismatched spectrometers. High noise suppression enables visible light OCT of the mouse retina at 70 kHz with 125 microwatts incident power, with an inexpensive, 30 MHz repetition rate supercontinuum source. Averaged images resolve the retinal pigment epithelium in a highly pigmented mouse strain.
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Affiliation(s)
- Aaron M. Kho
- Department of Biomedical Engineering, University of California Davis, Davis, California 95616, USA
| | - Vivek J. Srinivasan
- Department of Biomedical Engineering, University of California Davis, Davis, California 95616, USA
- Department of Ophthalmology and Vision Science, University of California Davis, Davis School of Medicine, Sacramento, California 96817, USA
- Department of Ophthalmology, NYU Langone Health, New York, New York 10017, USA
- Department of Radiology, NYU Langone Health, New York, New York 10016, USA
- Tech4Health Institute, NYU Langone Health, New York, New York 10010, USA
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24
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Pijewska E, Zhang P, Meina M, Meleppat RK, Szkulmowski M, Zawadzki RJ. Extraction of phase-based optoretinograms (ORG) from serial B-scans acquired over tens of seconds by mouse retinal raster scanning OCT system. BIOMEDICAL OPTICS EXPRESS 2021; 12:7849-7871. [PMID: 35003871 PMCID: PMC8713677 DOI: 10.1364/boe.439900] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 11/01/2021] [Accepted: 11/08/2021] [Indexed: 06/14/2023]
Abstract
Several specialized retinal optical coherence tomography (OCT) acquisition and processing methods have been recently developed to allow in vivo probing of light-evoked photoreceptors function, focusing on measurements in individual photoreceptors (rods and cones). Recent OCT investigations in humans and experimental animals have shown that the outer segments in dark-adapted rods and cones elongate in response to the visible optical stimuli that bleach fractions of their visual photopigment. We have previously successfully contributed to these developments by implementing OCT intensity-based "optoretinograms" (ORG), the paradigm of using near-infrared OCT (NIR OCT) to measure bleaching-induced back-scattering and/or elongation changes of photoreceptors in the eye in vivo. In parallel, several groups have successfully implemented phase-based ORGs, mainly in human studies, exploiting changes in the phases of back-scattered light. This allowed more sensitive observations of tiny alterations of photoreceptors structures. Applications of the phase-based ORG have been implemented primarily in high speed and cellular resolution AO-OCT systems that can visualize photoreceptor mosaic, allowing phase measurements of path length changes in outer segments of individual photoreceptors. The phase-based ORG in standard resolution OCT systems is much more demanding to implement and has not been explored extensively. This manuscript describes our efforts to implement a phase analysis framework to retinal images acquired with a standard resolution and raster scanning OCT system, which offers much lower phase stability than line-field or full-field OCT detection schemes due to the relatively slower acquisition speed. Our initial results showcase the successful extraction of phase-based ORG signal from the B-scans acquired at ∼100 Hz rate and its favorable comparison with intensity-based ORG signal extracted from the same data sets. We implemented the calculation of phase-based ORG signals using Knox-Thompson paths and modified signal recovery by adding decorrelation weights. The phase-sensitive ORG signal analysis developed here for mouse retinal raster scanning OCT systems could be in principle extended to clinical retinal raster scanning OCT systems, potentially opening doors for clinically friendly ORG probing.
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Affiliation(s)
- Ewelina Pijewska
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Toruń, Grudziądzka 5, 87-100 Torun, Poland
| | - Pengfei Zhang
- UC Davis Eyepod Imaging Laboratory, Dept. of Cell Biology and Human Anatomy, University of California Davis, 4320 Tupper Hall, Davis, CA 95616, USA
- School of Optoelectronic Engineering and Instrumentation Science, Dalian University of Technology, No. 2 Linggong Road, Ganjingzi District, Dalian City, Liaoning Province 116024, China
| | - Michał Meina
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Toruń, Grudziądzka 5, 87-100 Torun, Poland
| | - Ratheesh K. Meleppat
- UC Davis Eyepod Imaging Laboratory, Dept. of Cell Biology and Human Anatomy, University of California Davis, 4320 Tupper Hall, Davis, CA 95616, USA
| | - Maciej Szkulmowski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Toruń, Grudziądzka 5, 87-100 Torun, Poland
| | - Robert J. Zawadzki
- UC Davis Eyepod Imaging Laboratory, Dept. of Cell Biology and Human Anatomy, University of California Davis, 4320 Tupper Hall, Davis, CA 95616, USA
- Department of Ophthalmology & Vision Science, University of California Davis, 4860 Y Street Suite 2400 Sacramento, CA 95817, USA
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Lassoued A, Zhang F, Kurokawa K, Liu Y, Bernucci MT, Crowell JA, Miller DT. Cone photoreceptor dysfunction in retinitis pigmentosa revealed by optoretinography. Proc Natl Acad Sci U S A 2021; 118:e2107444118. [PMID: 34795055 PMCID: PMC8617487 DOI: 10.1073/pnas.2107444118] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/08/2021] [Indexed: 12/20/2022] Open
Abstract
Retinitis pigmentosa (RP) is the most common group of inherited retinal degenerative diseases, whose most debilitating phase is cone photoreceptor death. Perimetric and electroretinographic methods are the gold standards for diagnosing and monitoring RP and assessing cone function. However, these methods lack the spatial resolution and sensitivity to assess disease progression at the level of individual photoreceptor cells, where the disease originates and whose degradation causes vision loss. High-resolution retinal imaging methods permit visualization of human cone cells in vivo but have only recently achieved sufficient sensitivity to observe their function as manifested in the cone optoretinogram. By imaging with phase-sensitive adaptive optics optical coherence tomography, we identify a biomarker in the cone optoretinogram that characterizes individual cone dysfunction by stimulating cone cells with flashes of light and measuring nanometer-scale changes in their outer segments. We find that cone optoretinographic responses decrease with increasing RP severity and that even in areas where cone density appears normal, cones can respond differently than those in controls. Unexpectedly, in the most severely diseased patches examined, we find isolated cones that respond normally. Short-wavelength-sensitive cones are found to be more vulnerable to RP than medium- and long-wavelength-sensitive cones. We find that decreases in cone response and cone outer-segment length arise earlier in RP than changes in cone density but that decreases in response and length are not necessarily correlated within single cones.
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Affiliation(s)
- Ayoub Lassoued
- School of Optometry, Indiana University, Bloomington, IN 47405
| | - Furu Zhang
- School of Optometry, Indiana University, Bloomington, IN 47405
| | | | - Yan Liu
- School of Optometry, Indiana University, Bloomington, IN 47405
| | | | - James A Crowell
- School of Optometry, Indiana University, Bloomington, IN 47405
| | - Donald T Miller
- School of Optometry, Indiana University, Bloomington, IN 47405
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Mathis T, Vasseur V, Zuber K, Arej N, Loria O, Kodjikian L, Sennlaub F, Mauget‐Faÿsse M. Light-induced modifications of the outer retinal hyperreflective layers on spectral-domain optical coherence tomography in humans: an experimental study. Acta Ophthalmol 2021; 99:765-772. [PMID: 33393736 PMCID: PMC8596705 DOI: 10.1111/aos.14723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2019] [Revised: 11/14/2020] [Accepted: 11/23/2020] [Indexed: 11/28/2022]
Abstract
PURPOSE Numerous small hyperreflective dots (HRDs) can be seen within the hyporeflective layer between the ellipsoid zone (EZ) and the interdigitation zone (IZ) on C-scan spectral-domain optical coherence tomography (SD-OCT) with a yet unknown variation under light conditions. The aim of this study was to explore light-induced SD-OCT changes in these HRDs. METHODS The study subjects were randomly assigned to two groups: Group 1 experienced a dark adaptation protocol followed by intense retinal photobleaching, while Group 2, serving as the control group, was exposed to constant ambient light without any variation. The number of HRDs was automatically counted. RESULTS Twenty healthy volunteers were prospectively included. The number of HRDs differed significantly over time (p = 0.0013). They decreased in Group 1 after dark adaptation and retinal photobleaching before returning to baseline levels 30 min later; conversely, they remained relatively constant in Group 2 throughout the study (p < 0.001). Light-skinned subjects had less HRD than dark-skinned subjects. CONCLUSION We observed light-induced modifications in the space between the EZ and the IZ. We hypothesize that the HRDs visible in this zone correspond to melanosomes that are mobilized during the light stimulation protocol. Larger studies are recommended to further evaluate and confirm light-induced SD-OCT changes under physiological and pathological conditions.
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Affiliation(s)
- Thibaud Mathis
- Department of OphthalmologyCroix‐Rousse University HospitalHospices Civils de LyonUniversity of Medicine Lyon 1LyonFrance
- UMR‐CNRS 5510 MatéisLyon 1 UniversityLyonFrance
- INSERMCNRSInstitut de la VisionSorbonne UniversityParisFrance
| | - Vivien Vasseur
- Department of OphthalmologyRothschild FoundationParisFrance
| | - Kevin Zuber
- Department of OphthalmologyRothschild FoundationParisFrance
| | - Nicolas Arej
- Department of OphthalmologyRothschild FoundationParisFrance
| | - Olivier Loria
- Department of OphthalmologyCroix‐Rousse University HospitalHospices Civils de LyonUniversity of Medicine Lyon 1LyonFrance
- UMR‐CNRS 5510 MatéisLyon 1 UniversityLyonFrance
| | - Laurent Kodjikian
- Department of OphthalmologyCroix‐Rousse University HospitalHospices Civils de LyonUniversity of Medicine Lyon 1LyonFrance
- UMR‐CNRS 5510 MatéisLyon 1 UniversityLyonFrance
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27
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Desissaire S, Schwarzhans F, Steiner S, Vass C, Fischer G, Pircher M, Hitzenberger CK. Temporal phase evolution OCT for measurement of tissue deformation in the human retina in-vivo. BIOMEDICAL OPTICS EXPRESS 2021; 12:7092-7112. [PMID: 34858702 PMCID: PMC8606136 DOI: 10.1364/boe.440893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 10/13/2021] [Accepted: 10/13/2021] [Indexed: 05/08/2023]
Abstract
We demonstrate the use of temporal phase evolution (TPE-) OCT methods to evaluate retinal tissue deformation in-vivo over time periods of several seconds. A custom built spectral domain (SD)-OCT system with an integrated retinal tracker, ensuring stable imaging with sub-speckle precision, was used for imaging. TPE-OCT measures and images phase differences between an initial reference B-scan and each of the subsequent B-scans of the evaluated temporal sequence. In order to demonstrate the precision and repeatability of the measurements, retinal nerve fiber (RNF) tissue deformations induced by retinal vessels pulsating with the heartbeat were analyzed in several healthy subjects. We show TPE maps (M-scans of phase evolution as a function of position along B-scan trace vs. time) of wrapped phase data and corresponding deformation maps in selected regions of the RNF layer (RNFL) over the course of several cardiac cycles. A reproducible phase pattern is seen at each heartbeat cycle for all imaged volunteers. RNF tissue deformations near arteries and veins up to ∼ 1.6 µm were obtained with an average precision for a single pixel of about 30 nm. Differences of motion induced by arteries and veins are also investigated.
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Affiliation(s)
- Sylvia Desissaire
- Center for Medical Physics and Biomedical
Engineering, Medical University of Vienna,
Vienna, 1090, Austria
| | - Florian Schwarzhans
- Center for Medical Statistics, Informatics
and Intelligent Systems, Medical University of
Vienna, Vienna, 1090, Austria
| | - Stefan Steiner
- Department of Ophthalmology and Optometry,
Medical University of Vienna, Vienna, 1090,
Austria
| | - Clemens Vass
- Department of Ophthalmology and Optometry,
Medical University of Vienna, Vienna, 1090,
Austria
| | - Georg Fischer
- Center for Medical Statistics, Informatics
and Intelligent Systems, Medical University of
Vienna, Vienna, 1090, Austria
| | - Michael Pircher
- Center for Medical Physics and Biomedical
Engineering, Medical University of Vienna,
Vienna, 1090, Austria
| | - Christoph K. Hitzenberger
- Center for Medical Physics and Biomedical
Engineering, Medical University of Vienna,
Vienna, 1090, Austria
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Genovese F, Reisert J, Kefalov VJ. Sensory Transduction in Photoreceptors and Olfactory Sensory Neurons: Common Features and Distinct Characteristics. Front Cell Neurosci 2021; 15:761416. [PMID: 34690705 PMCID: PMC8531253 DOI: 10.3389/fncel.2021.761416] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 09/20/2021] [Indexed: 12/24/2022] Open
Abstract
The past decades have seen tremendous progress in our understanding of the function of photoreceptors and olfactory sensory neurons, uncovering the mechanisms that determine their properties and, ultimately, our ability to see and smell. This progress has been driven to a large degree by the powerful combination of physiological experimental tools and genetic manipulations, which has enabled us to identify the main molecular players in the transduction cascades of these sensory neurons, how their properties affect the detection and discrimination of stimuli, and how diseases affect our senses of vision and smell. This review summarizes some of the common and unique features of photoreceptors and olfactory sensory neurons that make these cells so exciting to study.
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Affiliation(s)
| | | | - Vladimir J Kefalov
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA, United States.,Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, United States
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29
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Lee KE, Heitkotter H, Carroll J. Challenges Associated With Ellipsoid Zone Intensity Measurements Using Optical Coherence Tomography. Transl Vis Sci Technol 2021; 10:27. [PMID: 34665233 PMCID: PMC8543396 DOI: 10.1167/tvst.10.12.27] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 09/16/2021] [Indexed: 12/11/2022] Open
Abstract
Translational Relevance Qualitative evaluation of the ellipsoid zone band on optical coherence tomography is a valuable clinical tool for assessing photoreceptor structure, though more quantitative metrics are emerging. Awareness of the challenges involved in interpreting quantitative metrics is important for their clinical translation.
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Affiliation(s)
- Karen E. Lee
- Medical College of Wisconsin, Milwaukee, WI, USA
| | - Heather Heitkotter
- Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Joseph Carroll
- Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA
- Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, USA
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30
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Leitgeb R, Placzek F, Rank E, Krainz L, Haindl R, Li Q, Liu M, Andreana M, Unterhuber A, Schmoll T, Drexler W. Enhanced medical diagnosis for dOCTors: a perspective of optical coherence tomography. JOURNAL OF BIOMEDICAL OPTICS 2021; 26:JBO-210150-PER. [PMID: 34672145 PMCID: PMC8528212 DOI: 10.1117/1.jbo.26.10.100601] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 09/23/2021] [Indexed: 05/17/2023]
Abstract
SIGNIFICANCE After three decades, more than 75,000 publications, tens of companies being involved in its commercialization, and a global market perspective of about USD 1.5 billion in 2023, optical coherence tomography (OCT) has become one of the fastest successfully translated imaging techniques with substantial clinical and economic impacts and acceptance. AIM Our perspective focuses on disruptive forward-looking innovations and key technologies to further boost OCT performance and therefore enable significantly enhanced medical diagnosis. APPROACH A comprehensive review of state-of-the-art accomplishments in OCT has been performed. RESULTS The most disruptive future OCT innovations include imaging resolution and speed (single-beam raster scanning versus parallelization) improvement, new implementations for dual modality or even multimodality systems, and using endogenous or exogenous contrast in these hybrid OCT systems targeting molecular and metabolic imaging. Aside from OCT angiography, no other functional or contrast enhancing OCT extension has accomplished comparable clinical and commercial impacts. Some more recently developed extensions, e.g., optical coherence elastography, dynamic contrast OCT, optoretinography, and artificial intelligence enhanced OCT are also considered with high potential for the future. In addition, OCT miniaturization for portable, compact, handheld, and/or cost-effective capsule-based OCT applications, home-OCT, and self-OCT systems based on micro-optic assemblies or photonic integrated circuits will revolutionize new applications and availability in the near future. Finally, clinical translation of OCT including medical device regulatory challenges will continue to be absolutely essential. CONCLUSIONS With its exquisite non-invasive, micrometer resolution depth sectioning capability, OCT has especially revolutionized ophthalmic diagnosis and hence is the fastest adopted imaging technology in the history of ophthalmology. Nonetheless, OCT has not been completely exploited and has substantial growth potential-in academics as well as in industry. This applies not only to the ophthalmic application field, but also especially to the original motivation of OCT to enable optical biopsy, i.e., the in situ imaging of tissue microstructure with a resolution approaching that of histology but without the need for tissue excision.
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Affiliation(s)
- Rainer Leitgeb
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
- Medical University of Vienna, Christian Doppler Laboratory OPTRAMED, Vienna, Austria
| | - Fabian Placzek
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
| | - Elisabet Rank
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
| | - Lisa Krainz
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
| | - Richard Haindl
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
| | - Qian Li
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
| | - Mengyang Liu
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
| | - Marco Andreana
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
| | - Angelika Unterhuber
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
| | - Tilman Schmoll
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
- Carl Zeiss Meditec, Inc., Dublin, California, United States
| | - Wolfgang Drexler
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
- Address all correspondence to Wolfgang Drexler,
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31
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Gaffney M, Cooper RF, Cava JA, Follett HM, Salmon AE, Freling S, Yu CT, Merriman DK, Carroll J. Cone photoreceptor reflectance variation in the northern tree shrew and thirteen-lined ground squirrel. Exp Biol Med (Maywood) 2021; 246:2192-2201. [PMID: 34308656 PMCID: PMC8718250 DOI: 10.1177/15353702211029582] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 06/14/2021] [Indexed: 12/30/2022] Open
Abstract
In vivo images of human cone photoreceptors have been shown to vary in their reflectance both spatially and temporally. While it is generally accepted that the unique anatomy and physiology of the photoreceptors themselves drives this behavior, the exact mechanisms have not been fully elucidated as most studies on these phenomena have been limited to the human retina. Unlike humans, animal models offer the ability to experimentally manipulate the retina and perform direct in vivo and ex vivo comparisons. The thirteen-lined ground squirrel and northern tree shrew are two emerging animal models being used in vision research. Both models feature cone-dominant retinas, overcoming a key limitation of traditional rodent models. Additionally, each possesses unique but well-documented anatomical differences in cone structure compared to human cones, which can be leveraged to further constrain theoretical models of light propagation within photoreceptors. Here we sought to characterize the spatial and temporal reflectance behavior of cones in these species. Adaptive optics scanning light ophthalmoscopy (AOSLO) was used to non-invasively image the photoreceptors of both species at 5 to 10 min intervals over the span of 18 to 25 min. The reflectance of individual cone photoreceptors was measured over time, and images at individual time points were used to assess the variability of cone reflectance across the cone mosaic. Variability in spatial and temporal photoreceptor reflectance was observed in both species, with similar behavior to that seen in human AOSLO images. Despite the unique cone structure in these animals, these data suggest a common origin of photoreceptor reflectance behavior across species. Such data may help constrain models of the cellular origins of photoreceptor reflectance signals. These animal models provide an experimental platform to further explore the morphological origins of light capture and propagation.
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Affiliation(s)
- Mina Gaffney
- Department of Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Robert F Cooper
- Department of Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Department of Biomedical Engineering, Marquette University, Milwaukee, WI 53233, USA
| | - Jenna A Cava
- Department of Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Hannah M Follett
- Department of Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Alexander E Salmon
- Department of Cell Biology, Neurobiology, & Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Translational Imaging Innovations, Inc., Hickory, NC 28601, USA
| | - Susan Freling
- Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458, USA
| | - Ching T Yu
- Department of Cell Biology, Neurobiology, & Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Dana K Merriman
- Department of Biology, University of Wisconsin Oshkosh, Oshkosh, WI 54901, USA
| | - Joseph Carroll
- Department of Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Department of Biomedical Engineering, Marquette University, Milwaukee, WI 53233, USA
- Department of Cell Biology, Neurobiology, & Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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Retinal degeneration-3 protein attenuates photoreceptor degeneration in transgenic mice expressing dominant mutation of human retinal guanylyl cyclase. J Biol Chem 2021; 297:101201. [PMID: 34537244 PMCID: PMC8517212 DOI: 10.1016/j.jbc.2021.101201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 09/10/2021] [Accepted: 09/12/2021] [Indexed: 11/22/2022] Open
Abstract
Different forms of photoreceptor degeneration cause blindness. Retinal degeneration-3 protein (RD3) deficiency in photoreceptors leads to recessive congenital blindness. We proposed that aberrant activation of the retinal membrane guanylyl cyclase (RetGC) by its calcium-sensor proteins (guanylyl cyclase-activating protein [GCAP]) causes this retinal degeneration and that RD3 protects photoreceptors by preventing such activation. We here present in vivo evidence that RD3 protects photoreceptors by suppressing activation of both RetGC1 and RetGC2 isozymes. We further suggested that insufficient inhibition of RetGC by RD3 could contribute to some dominant forms of retinal degeneration. The R838S substitution in RetGC1 that causes autosomal-dominant cone-rod dystrophy 6, not only impedes deceleration of RetGC1 activity by Ca2+GCAPs but also elevates this isozyme's resistance to inhibition by RD3. We found that RD3 prolongs the survival of photoreceptors in transgenic mice harboring human R838S RetGC1 (R838S+). Overexpression of GFP-tagged human RD3 did not improve the calcium sensitivity of cGMP production in R838S+ retinas but slowed the progression of retinal blindness and photoreceptor degeneration. Fluorescence of the GFP-tagged RD3 in the retina only partially overlapped with immunofluorescence of RetGC1 or GCAP1, indicating that RD3 separates from the enzyme before the RetGC1:GCAP1 complex is formed in the photoreceptor outer segment. Most importantly, our in vivo results indicate that, in addition to the abnormal Ca2+ sensitivity of R838S RetGC1 in the outer segment, the mutated RetGC1 becomes resistant to inhibition by RD3 in a different cellular compartment(s) and suggest that RD3 overexpression could be utilized to reduce the severity of cone-rod dystrophy 6 pathology.
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Jonnal RS. Toward a clinical optoretinogram: a review of noninvasive, optical tests of retinal neural function. ANNALS OF TRANSLATIONAL MEDICINE 2021; 9:1270. [PMID: 34532407 PMCID: PMC8421939 DOI: 10.21037/atm-20-6440] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 07/12/2021] [Indexed: 11/17/2022]
Abstract
The past few years have witnessed rapid development of the optoretinogram-a noninvasive, optical measurement of neural function in the retina, and especially the photoreceptors (Ph). While its recent development has been rapid, it represents the culmination of hundreds of experiments spanning decades. Early work showed measurable and reproducible changes in the optical properties of retinal explants and suspensions of Ph, and uncovered some of the biophysical and biochemical mechanisms underlying them. That work thus provided critical motivation for more recent work based on clinical imaging platforms, whose eventual goal is the improvement of ophthalmic care and streamlining the discovery of novel therapeutics. The first part of this review consists of a selective summary of the early work, and identifies four kinds of stimulus-evoked optical signals that have emerged from it: changes in light scattered from the membranous discs of the Ph's outer segment (OS), changes in light scattered by the front and back boundaries of the OS, rearrangement of scattering material in and near the OS, and changes in the OS length. In the past decade, all four of these signals have continued to be investigated using imaging systems already used in the clinic or intended for clinical and translational use. The second part of this review discusses these imaging modalities, their potential to detect and quantify the signals of interest, and other factors influencing their translational promise. Particular attention is paid to phase-sensitive optical coherence tomography (OCT) with adaptive optics (AO), a method in which both the amplitude and the phase of light reflected from individual Ph is monitored as visible stimuli are delivered to them. The record of the light's phase is decoded to reveal a reproducible pattern of deformation in the OS, while the amplitude reveals changes in scattering and structural rearrangements. The method has been demonstrated in a few labs and has been used to measure responses from both rods and cones. With the ability to detect responses to stimuli isomerizing less than 0.01% of photopigment, this technique may prove to be a quick, noninvasive, and objective way to measure subtle disease-related dysfunction at the cellular level, and thus to provide an entirely new and complementary biomarker for retinal disease and recovery.
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Wynne N, Carroll J, Duncan JL. Promises and pitfalls of evaluating photoreceptor-based retinal disease with adaptive optics scanning light ophthalmoscopy (AOSLO). Prog Retin Eye Res 2021; 83:100920. [PMID: 33161127 PMCID: PMC8639282 DOI: 10.1016/j.preteyeres.2020.100920] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 10/28/2020] [Accepted: 10/31/2020] [Indexed: 12/15/2022]
Abstract
Adaptive optics scanning light ophthalmoscopy (AOSLO) allows visualization of the living human retina with exquisite single-cell resolution. This technology has improved our understanding of normal retinal structure and revealed pathophysiological details of a number of retinal diseases. Despite the remarkable capabilities of AOSLO, it has not seen the widespread commercial adoption and mainstream clinical success of other modalities developed in a similar time frame. Nevertheless, continued advancements in AOSLO hardware and software have expanded use to a broader range of patients. Current devices enable imaging of a number of different retinal cell types, with recent improvements in stimulus and detection schemes enabling monitoring of retinal function, microscopic structural changes, and even subcellular activity. This has positioned AOSLO for use in clinical trials, primarily as exploratory outcome measures or biomarkers that can be used to monitor disease progression or therapeutic response. AOSLO metrics could facilitate patient selection for such trials, to refine inclusion criteria or to guide the choice of therapy, depending on the presence, absence, or functional viability of specific cell types. Here we explore the potential of AOSLO retinal imaging by reviewing clinical applications as well as some of the pitfalls and barriers to more widespread clinical adoption.
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Affiliation(s)
- Niamh Wynne
- Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Joseph Carroll
- Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, USA; Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA; Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Jacque L Duncan
- Department of Ophthalmology, University of California, San Francisco, CA, USA.
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35
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Berkowitz BA, Qian H. OCT imaging of rod mitochondrial respiration in vivo. Exp Biol Med (Maywood) 2021; 246:2151-2158. [PMID: 34024141 DOI: 10.1177/15353702211013799] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
There remains a need for high spatial resolution imaging indices of mitochondrial respiration in the outer retina that probe normal physiology and measure pathogenic and reversible conditions underlying loss of vision. Mitochondria are involved in a critical, but somewhat underappreciated, support system that maintains the health of the outer retina involving stimulus-evoked changes in subretinal space hydration. The subretinal space hydration light-dark response is important because it controls the distribution of vision-critical interphotoreceptor matrix components, including anti-oxidants, pro-survival factors, ions, and metabolites. The underlying signaling pathway controlling subretinal space water management has been worked out over the past 30 years and involves cGMP/mitochondria respiration/pH/RPE water efflux. This signaling pathway has also been shown to be modified by disease-generating conditions, such as hypoxia or oxidative stress. Here, we review recent advances in MRI and commercially available OCT technologies that can measure stimulus-evoked changes in subretinal space water content based on changes in the external limiting membrane-retinal pigment epithelium region. Each step within the above signaling pathway can also be interrogated with FDA-approved pharmaceuticals. A highlight of these studies is the demonstration of first-in-kind in vivo imaging of mitochondria respiration of any cell in the body. Future examinations of subretinal space hydration are expected to be useful for diagnosing threats to sight in aging and disease, and improving the success rate when translating treatments from bench-to-bedside.
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Affiliation(s)
- Bruce A Berkowitz
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Haohua Qian
- Visual Function Core, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
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Gao S, Li Y, Bissig D, Cohen ED, Podolsky RH, Childers KL, Vernon G, Chen S, Berkowitz BA, Qian H. Functional regulation of an outer retina hyporeflective band on optical coherence tomography images. Sci Rep 2021; 11:10260. [PMID: 33986362 PMCID: PMC8119672 DOI: 10.1038/s41598-021-89599-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 04/27/2021] [Indexed: 12/30/2022] Open
Abstract
Human and animal retinal optical coherence tomography (OCT) images show a hyporeflective band (HB) between the photoreceptor tip and retinal pigment epithelium layers whose mechanisms are unclear. In mice, HB magnitude and the external limiting membrane-retinal pigment epithelium (ELM-RPE) thickness appear to be dependent on light exposure, which is known to alter photoreceptor mitochondria respiration. Here, we test the hypothesis that these two OCT biomarkers are linked to metabolic activity of the retina. Acetazolamide, which acidifies the subretinal space, had no significant impact on HB magnitude but produced ELM-RPE thinning. Mitochondrial stimulation with 2,4-dinitrophenol reduced both HB magnitude and ELM-RPE thickness in parallel, and also reduced F-actin expression in the same retinal region, but without altering ERG responses. For mice strains with relatively lower (C57BL/6J) or higher (129S6/ev) rod mitochondrial efficacy, light-induced changes in HB magnitude and ELM-RPE thickness were correlated. Humans, analyzed from published data captured with a different protocol, showed a similar light-dark change pattern in HB magnitude as in the mice. Our results indicate that mitochondrial respiration underlies changes in HB magnitude upstream of the pH-sensitive ELM-RPE thickness response. These two distinct OCT biomarkers could be useful indices for non-invasively evaluating photoreceptor mitochondrial metabolic activity.
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Affiliation(s)
- Shasha Gao
- Department of Ophthalmology, the First Affiliated Hospital, Zhengzhou University, Zhengzhou, China
- Visual Function Core, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Yichao Li
- Visual Function Core, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - David Bissig
- Department of Neurology, University of California Davis, Sacramento, CA, USA
| | - Ethan D Cohen
- Division of Biomedical Physics, Office of Science and Engineering Labs, Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, MD, USA
| | - Robert H Podolsky
- Beaumont Research Institute, Beaumont Health, Royal Oak, MI, 48073, USA
| | | | - Gregory Vernon
- Visual Function Core, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Sonia Chen
- Visual Function Core, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Bruce A Berkowitz
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, USA
| | - Haohua Qian
- Visual Function Core, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
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Gulati S, Palczewski K. New focus on regulation of the rod photoreceptor phosphodiesterase. Curr Opin Struct Biol 2021; 69:99-107. [PMID: 33945959 DOI: 10.1016/j.sbi.2021.03.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 02/18/2021] [Accepted: 03/25/2021] [Indexed: 02/03/2023]
Abstract
Rod photoreceptor phosphodiesterase (PDE6) is the key catalytic enzyme of visual phototransduction. PDE6 is the only member of the phosphodiesterase family that consists of a heterodimeric catalytic core composed of PDE6α and PDE6β subunits and two inhibitory PDE6γ subunits. Both PDE6α and PDE6β contain two regulatory GAF domains and one catalytic domain. GAF domains and the tightly bound PDE6γ subunits allosterically regulate the activity of the catalytic domain in association with the GTP-bound transducin alpha subunit (Gtα-GTP). Recent cryo-electron microscopy structures of the PDE6αγβγ and PDE6αγβγ-(Gtα-GTP)2 complexes have provided valuable knowledge shedding additional light on the allosteric activation of PDE6 by Gtα-GTP. Here we discuss recent developments in our understanding of the mechanism of PDE6 activation.
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Affiliation(s)
| | - Krzysztof Palczewski
- Gavin Herbert Eye Institute and the Department of Ophthalmology, Center for Translational Vision Research, University of California, 829 Health Sciences Road, Irvine, CA 92617, USA; The Department of Physiology & Biophysics, University of California, Irvine, CA 92697, USA; The Department of Chemistry, University of California, Irvine, CA 92697, USA.
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Ma G, Son T, Kim TH, Yao X. Functional optoretinography: concurrent OCT monitoring of intrinsic signal amplitude and phase dynamics in human photoreceptors. BIOMEDICAL OPTICS EXPRESS 2021; 12:2661-2669. [PMID: 34123495 PMCID: PMC8176815 DOI: 10.1364/boe.423733] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 03/31/2021] [Accepted: 04/02/2021] [Indexed: 05/12/2023]
Abstract
Intrinsic optical signal (IOS) imaging promises a noninvasive method for objective assessment of retinal function. This study demonstrates concurrent optical coherence tomography (OCT) of amplitude-IOS and phase-IOS changes in human photoreceptors. A new procedure for differential-phase-mapping (DPM) is validated to enable depth-resolved phase-IOS imaging. Dynamic OCT revealed rapid amplitude-IOS and phase-IOS changes, which occur almost right away after the stimulus onset. These IOS changes were predominantly observed within the photoreceptor outer segment (OS), particularly two boundaries connecting to the inner segment and retinal pigment epithelium. The comparative analysis supports that both amplitude-IOS and phase-IOS attribute to transient OS morphological change associated with phototransduction activation in retinal photoreceptors. A simulation modeling is proposed to discuss the relationship between the photoreceptor OS length and phase-IOS changes.
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Affiliation(s)
- Guangying Ma
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Taeyoon Son
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Tae-Hoon Kim
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Xincheng Yao
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL 60612, USA
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Functional compartmentalization of photoreceptor neurons. Pflugers Arch 2021; 473:1493-1516. [PMID: 33880652 DOI: 10.1007/s00424-021-02558-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 03/15/2021] [Accepted: 03/22/2021] [Indexed: 12/16/2022]
Abstract
Retinal photoreceptors are neurons that convert dynamically changing patterns of light into electrical signals that are processed by retinal interneurons and ultimately transmitted to vision centers in the brain. They represent the essential first step in seeing without which the remainder of the visual system is rendered moot. To support this role, the major functions of photoreceptors are segregated into three main specialized compartments-the outer segment, the inner segment, and the pre-synaptic terminal. This compartmentalization is crucial for photoreceptor function-disruption leads to devastating blinding diseases for which therapies remain elusive. In this review, we examine the current understanding of the molecular and physical mechanisms underlying photoreceptor functional compartmentalization and highlight areas where significant knowledge gaps remain.
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Son T, Kim TH, Ma G, Kim H, Yao X. Functional intrinsic optical signal imaging for objective optoretinography of human photoreceptors. Exp Biol Med (Maywood) 2021; 246:639-643. [PMID: 33307802 PMCID: PMC7988726 DOI: 10.1177/1535370220978898] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 11/16/2020] [Indexed: 12/18/2022] Open
Abstract
Functional mapping of photoreceptor physiology is important for better disease diagnosis and treatment assessment. Fast intrinsic optical signal (IOS), which arises before light-evoked pupillary response, promises a unique biomarker of photoreceptor physiology for objective optoretinography with high resolution. This study is to test the feasibility of non-mydriatic IOS mapping of retinal photoreceptors in awake human. Depth-resolved optical coherence tomography verified outer segment (OS) as the anatomic origin of fast photoreceptor-IOS. Dynamic IOS changes are primarily confined at OS boundaries connected with inner segment and retinal pigment epithelium, supporting transient OS shrinkage due to phototransduction process as the mechanism of the fast photoreceptor-IOS response.
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Affiliation(s)
- Taeyoon Son
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Tae-Hoon Kim
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Guangying Ma
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Hoonsup Kim
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Xincheng Yao
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL 60612, USA
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41
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Barnes CL, Malhotra H, Calvert PD. Compartmentalization of Photoreceptor Sensory Cilia. Front Cell Dev Biol 2021; 9:636737. [PMID: 33614665 PMCID: PMC7889997 DOI: 10.3389/fcell.2021.636737] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 01/07/2021] [Indexed: 12/12/2022] Open
Abstract
Functional compartmentalization of cells is a universal strategy for segregating processes that require specific components, undergo regulation by modulating concentrations of those components, or that would be detrimental to other processes. Primary cilia are hair-like organelles that project from the apical plasma membranes of epithelial cells where they serve as exclusive compartments for sensing physical and chemical signals in the environment. As such, molecules involved in signal transduction are enriched within cilia and regulating their ciliary concentrations allows adaptation to the environmental stimuli. The highly efficient organization of primary cilia has been co-opted by major sensory neurons, olfactory cells and the photoreceptor neurons that underlie vision. The mechanisms underlying compartmentalization of cilia are an area of intense current research. Recent findings have revealed similarities and differences in molecular mechanisms of ciliary protein enrichment and its regulation among primary cilia and sensory cilia. Here we discuss the physiological demands on photoreceptors that have driven their evolution into neurons that rely on a highly specialized cilium for signaling changes in light intensity. We explore what is known and what is not known about how that specialization appears to have driven unique mechanisms for photoreceptor protein and membrane compartmentalization.
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Affiliation(s)
| | | | - Peter D. Calvert
- Department of Ophthalmology and Visual Sciences, Center for Vision Research, SUNY Upstate Medical University, Syracuse, NY, United States
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Cooper RF, Brainard DH, Morgan JIW. Optoretinography of individual human cone photoreceptors. OPTICS EXPRESS 2020; 28:39326-39339. [PMID: 33379485 PMCID: PMC7771891 DOI: 10.1364/oe.409193] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 12/02/2020] [Accepted: 12/03/2020] [Indexed: 05/03/2023]
Abstract
Photoreceptors mediate the first step of vision, transducing light and passing signals to retinal neurons that ultimately send signals along the optic nerve to the brain. A functional deficiency in the photoreceptors, due to either congenital or acquired disease, can significantly affect an individual's sight and quality of life. Methods for quantifying the health and function of photoreceptors are essential for understanding both the progression of disease and the efficacy of treatment. Given that emerging treatments such as gene, stem cell, and small molecule therapy are designed to operate at the cellular scale, it is desirable to monitor function at the commensurate resolution of individual photoreceptors. Previously, non-invasive imaging methods for visualizing photoreceptor mosaic structure have been used to infer photoreceptor health, but these methods do not assess function directly. Conversely, most functional techniques, such as ERG and conventional microperimetry, measure function by aggregating the effects of signals from many photoreceptors. We have previously shown that stimulus-evoked intrinsic changes in intensity can be measured reliably in populations of cone photoreceptors in the intact human eye, a measurement we refer to more generally as the cone optoretinogram. Here we report that we can resolve the intensity optoretinogram at the level of individual cones. Moreover, we show that the individual cone optoretinogram exhibits two key signatures expected of a functional measure. First, responses in individual cones increase systematically as a function of stimulus irradiance. Second, we can use the amplitude of the functional response to middle wavelength (545 nm) light to separate the population of short-wavelength-sensitive (S) cones from the population of middle- and long-wavelength-sensitive (L and M) cones. Our results demonstrate the promise of optoretinography as a direct diagnostic measure of individual cone function in the living human eye.
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Affiliation(s)
- Robert F Cooper
- Department of Psychology, University of Pennsylvania, Philadelphia, PA 19104, USA
- Scheie Eye Institute, Department of Ophthalmology, University of Pennsylvania, Philadelphia, PA 19104, USA
- Currently at the Joint Department of Biomedical Engineering, Marquette University and Medical College of Wisconsin and the Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, WI 53233, USA
| | - David H Brainard
- Department of Psychology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jessica I. W. Morgan
- Scheie Eye Institute, Department of Ophthalmology, University of Pennsylvania, Philadelphia, PA 19104, USA
- Center for Advanced Retinal and Ocular Therapeutics, University of Pennsylvania, Philadelphia, PA 19104, USA
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Abd El-Sadek I, Miyazawa A, Tzu-Wei Shen L, Makita S, Fukuda S, Yamashita T, Oka Y, Mukherjee P, Matsusaka S, Oshika T, Kano H, Yasuno Y. Optical coherence tomography-based tissue dynamics imaging for longitudinal and drug response evaluation of tumor spheroids. BIOMEDICAL OPTICS EXPRESS 2020; 11:6231-6248. [PMID: 33282486 PMCID: PMC7687946 DOI: 10.1364/boe.404336] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 09/30/2020] [Accepted: 10/01/2020] [Indexed: 05/18/2023]
Abstract
We present optical coherence tomography (OCT)-based tissue dynamics imaging method to visualize and quantify tissue dynamics such as subcellular motion based on statistical analysis of rapid-time-sequence OCT signals at the same location. The analyses include logarithmic intensity variance (LIV) method and two types of OCT correlation decay speed analysis (OCDS). LIV is sensitive to the magnitude of the signal fluctuations, while OCDSs including early- and late-OCDS (OCDS e and OCDS l , respectively) are sensitive to the fast and slow tissue dynamics, respectively. These methods were able to visualize and quantify the longitudinal necrotic process of a human breast adenocarcinoma spheroid and its anti-cancer drug response. Additionally, the effects of the number of OCT signals and the total acquisition time on dynamics imaging are examined. Small number of OCT signals, e.g., five or nine suffice for dynamics imaging when the total acquisition time is suitably long.
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Affiliation(s)
| | - Arata Miyazawa
- Computational Optics Group, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Larina Tzu-Wei Shen
- Clinical Research and Regional Innovation, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Shuichi Makita
- Computational Optics Group, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Shinichi Fukuda
- Department of Ophthalmology, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
- Department of Advanced Vision Science, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Toshiharu Yamashita
- Laboratory of Regenerative Medicine and Stem Cell Biology, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Yuki Oka
- Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Pradipta Mukherjee
- Computational Optics Group, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Satoshi Matsusaka
- Clinical Research and Regional Innovation, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Tetsuro Oshika
- Department of Ophthalmology, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Hideaki Kano
- Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Yoshiaki Yasuno
- Computational Optics Group, University of Tsukuba, Tsukuba, Ibaraki, Japan
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Boyle KC, Chen ZC, Ling T, Pandiyan VP, Kuchenbecker J, Sabesan R, Palanker D. Mechanisms of Light-Induced Deformations in Photoreceptors. Biophys J 2020; 119:1481-1488. [PMID: 33031739 PMCID: PMC7642315 DOI: 10.1016/j.bpj.2020.09.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 09/02/2020] [Accepted: 09/08/2020] [Indexed: 01/11/2023] Open
Abstract
Biological cells deform on a nanometer scale when their transmembrane voltage changes, an effect that has been visualized during the action potential using quantitative phase imaging. Similar changes in the optical path length have been observed in photoreceptor outer segments after a flash stimulus via phase-resolved optical coherence tomography. These optoretinograms reveal a fast, millisecond-scale contraction of the outer segments by tens of nanometers, followed by a slow (hundreds of milliseconds) elongation reaching hundreds of nanometers. Ultrafast measurements of the contractile response using line-field phase-resolved optical coherence tomography show a logarithmic increase in amplitude and a decreasing time to peak with increasing stimulus intensity. We present a model that relates the early receptor potential to these deformations based on the voltage-dependent membrane tension-the mechanism observed earlier in neurons and other electrogenic cells. The early receptor potential is caused by conformational changes in opsins after photoisomerization, resulting in the fractional shift of the charge across the disk membrane. Lateral repulsion of the ions on both sides of the membrane affects its surface tension and leads to its lateral expansion. Because the volume of the disks does not change on a millisecond timescale, their lateral expansion leads to an axial contraction of the outer segment. With increasing stimulus intensity and the resulting tension, the area expansion coefficient of the disk membrane also increases as thermally induced fluctuations are pulled flat, resisting further expansion. This leads to the logarithmic saturation observed in measurements as well as the peak shift in time. This imaging technique therefore relates the structural changes in the photoreceptor to the underlying neurological function of transducing light into electrical signals. Such label-free optical monitoring of neural activity using fast interferometry may be applicable not only to optoretinography but also to neuroscience in general.
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Affiliation(s)
- K C Boyle
- Department of Electrical Engineering, Stanford University, Stanford, California; Hansen Experimental Physics Laboratory, Stanford University, Stanford, California.
| | - Z C Chen
- Department of Electrical Engineering, Stanford University, Stanford, California; Hansen Experimental Physics Laboratory, Stanford University, Stanford, California
| | - T Ling
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, California; Department of Ophthalmology, Stanford University, Stanford, California
| | - V P Pandiyan
- Department of Ophthalmology, University of Washington, Seattle, Washington
| | - J Kuchenbecker
- Department of Ophthalmology, University of Washington, Seattle, Washington
| | - R Sabesan
- Department of Ophthalmology, University of Washington, Seattle, Washington.
| | - D Palanker
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, California; Department of Ophthalmology, Stanford University, Stanford, California.
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Sectoral activation of glia in an inducible mouse model of autosomal dominant retinitis pigmentosa. Sci Rep 2020; 10:16967. [PMID: 33046772 PMCID: PMC7552392 DOI: 10.1038/s41598-020-73749-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Accepted: 09/18/2020] [Indexed: 12/20/2022] Open
Abstract
Retinitis pigmentosa (RP) is a group of blinding disorders caused by diverse mutations, including in rhodopsin (RHO). Effective therapies have yet to be discovered. The I307N Rho mouse is a light-inducible model of autosomal dominant RP. Our purpose was to describe the glial response in this mouse model to educate future experimentation. I307N Rho mice were exposed to 20,000 lx of light for thirty minutes to induce retinal degeneration. Immunofluorescence staining of cross-sections and flat-mounts was performed to visualize the response of microglia and Müller glia. Histology was correlated with spectral-domain optical coherence tomography imaging (SD-OCT). Microglia dendrites extended between photoreceptors within two hours of induction, withdrew their dendrites between twelve hours and one day, appeared ameboid by three days, and assumed a ramified morphology by one month. Glial activation was more robust in the inferior retina and modulated across the boundary of light damage. SD-OCT hyper-reflectivity overlapped with activated microglia. Finally, microglia transiently adhered to the RPE before which RPE cells appeared dysmorphic. Our data demonstrate the spatial and temporal pattern of glial activation in the I307N Rho mouse, and correlate these patterns with SD-OCT images, assisting in interpretation of SD-OCT images in preclinical models and in human RP.
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Miller DT, Kurokawa K. Cellular-Scale Imaging of Transparent Retinal Structures and Processes Using Adaptive Optics Optical Coherence Tomography. Annu Rev Vis Sci 2020; 6:115-148. [PMID: 32609578 PMCID: PMC7864592 DOI: 10.1146/annurev-vision-030320-041255] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
High-resolution retinal imaging is revolutionizing how scientists and clinicians study the retina on the cellular scale. Its exquisite sensitivity enables time-lapse optical biopsies that capture minute changes in the structure and physiological processes of cells in the living eye. This information is increasingly used to detect disease onset and monitor disease progression during early stages, raising the possibility of personalized eye care. Powerful high-resolution imaging tools have been in development for more than two decades; one that has garnered considerable interest in recent years is optical coherence tomography enhanced with adaptive optics. State-of-the-art adaptive optics optical coherence tomography (AO-OCT) makes it possible to visualize even highly transparent cells and measure some of their internal processes at all depths within the retina, permitting reconstruction of a 3D view of the living microscopic retina. In this review, we report current AO-OCT performance and its success in visualizing and quantifying these once-invisible cells in human eyes.
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Affiliation(s)
- Donald T Miller
- School of Optometry, Indiana University, Bloomington, Indiana 47405, USA; ,
| | - Kazuhiro Kurokawa
- School of Optometry, Indiana University, Bloomington, Indiana 47405, USA; ,
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47
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Structural imaging of the retina in psychosis spectrum disorders: current status and perspectives. Curr Opin Psychiatry 2020; 33:476-483. [PMID: 32639357 DOI: 10.1097/yco.0000000000000624] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW Structural changes of the retina in schizophrenia and other psychotic disorders seem plausible as these conditions are accompanied by widespread morphological abnormalities of the brain. Advances in structural retinal imaging have led to the possibility of precise quantification of individual retinal layers, using optical coherence tomography (OCT) scanners. RECENT FINDINGS The aggregation of information related to OCT findings in schizophrenia has resulted in three metaanalyses, which are currently described. Areas where retinal changes were reported include retinal nerve fiber layer (RNFL), ganglion cell layer complex (GCC), macular volume, and macular thickness, but findings on affected retinal segments vary to some extent across studies. Discrepancies in individual studies could be because of small samples, heterogeneity within schizophrenia (phase of the illness, illness duration, predominant symptomatology), inconsistent reporting of antipsychotic therapy, insufficient control of confounding variables (somatic comorbidities, smoking, and so on), and use of the different types of OCT scanners. SUMMARY Exploration of potential disturbances in retinal architecture could provide new insights into neuronal changes associated with psychosis spectrum disorders, with potential to elucidate the nature and timing of developmental, progressive, inflammatory, and degenerative aspects of neuropathology and pathophysiology, and to assist with characterizing heterogeneity and facilitating personalized treatment approaches.
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Pandiyan VP, Maloney-Bertelli A, Kuchenbecker JA, Boyle KC, Ling T, Chen ZC, Park BH, Roorda A, Palanker D, Sabesan R. The optoretinogram reveals the primary steps of phototransduction in the living human eye. SCIENCE ADVANCES 2020; 6:6/37/eabc1124. [PMID: 32917686 PMCID: PMC9222118 DOI: 10.1126/sciadv.abc1124] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 07/24/2020] [Indexed: 05/05/2023]
Abstract
Photoreceptors initiate vision by converting photons to electrical activity. The onset of the phototransduction cascade is marked by the isomerization of photopigments upon light capture. We revealed that the onset of phototransduction is accompanied by a rapid (<5 ms), nanometer-scale electromechanical deformation in individual human cone photoreceptors. Characterizing this biophysical phenomenon associated with phototransduction in vivo was enabled by high-speed phase-resolved optical coherence tomography in a line-field configuration that allowed sufficient spatiotemporal resolution to visualize the nanometer/millisecond-scale light-induced shape change in photoreceptors. The deformation was explained as the optical manifestation of electrical activity, caused due to rapid charge displacement following isomerization, resulting in changes of electrical potential and surface tension within the photoreceptor disc membranes. These all-optical recordings of light-induced activity in the human retina constitute an optoretinogram and hold remarkable potential to reveal the biophysical correlates of neural activity in health and disease.
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Affiliation(s)
| | | | | | - Kevin C Boyle
- Hansen Experimental Physics Laboratory, Stanford, CA 94305, USA
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Tong Ling
- Hansen Experimental Physics Laboratory, Stanford, CA 94305, USA
- Department of Ophthalmology, Stanford University, Stanford, CA 94305, USA
| | - Zhijie Charles Chen
- Hansen Experimental Physics Laboratory, Stanford, CA 94305, USA
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA
| | - B Hyle Park
- Department of Bioengineering, University of California, Riverside, CA 92521, USA
| | - Austin Roorda
- School of Optometry, University of California, Berkeley, CA 94720, USA
| | - Daniel Palanker
- Hansen Experimental Physics Laboratory, Stanford, CA 94305, USA
- Department of Ophthalmology, Stanford University, Stanford, CA 94305, USA
| | - Ramkumar Sabesan
- Department of Ophthalmology, University of Washington, Seattle, WA 98109, USA.
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Pandiyan VP, Jiang X, Maloney-Bertelli A, Kuchenbecker JA, Sharma U, Sabesan R. High-speed adaptive optics line-scan OCT for cellular-resolution optoretinography. BIOMEDICAL OPTICS EXPRESS 2020; 11:5274-5296. [PMID: 33014614 PMCID: PMC7510866 DOI: 10.1364/boe.399034] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 08/05/2020] [Accepted: 08/19/2020] [Indexed: 05/15/2023]
Abstract
Optoretinography-the non-invasive, optical imaging of light-induced functional activity in the retina-stands to provide a critical biomarker for testing the safety and efficacy of new therapies as well as their rapid translation to the clinic. Optical phase change in response to light, as readily accessible in phase-resolved OCT, offers a path towards all-optical imaging of retinal function. However, typical human eye motion adversely affects phase stability. In addition, recording fast light-induced retinal events necessitates high-speed acquisition. Here, we introduce a high-speed line-scan spectral domain OCT with adaptive optics (AO), aimed at volumetric imaging and phase-resolved acquisition of retinal responses to light. By virtue of parallel acquisition of an entire retinal cross-section (B-scan) in a single high-speed camera frame, depth-resolved tomograms at speeds up to 16 kHz were achieved with high sensitivity and phase stability. To optimize spectral and spatial resolution, an anamorphic detection paradigm was introduced, enabling improved light collection efficiency and signal roll-off compared to traditional methods. The benefits in speed, resolution and sensitivity were exemplified in imaging nanometer-millisecond scale light-induced optical path length changes in cone photoreceptor outer segments. With 660 nm stimuli, individual cone responses readily segregated into three clusters, corresponding to long, middle, and short-wavelength cones. Recording such optoretinograms on spatial scales ranging from individual cones, to 100 µm-wide retinal patches offers a robust and sensitive biomarker for cone function in health and disease.
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Affiliation(s)
- Vimal Prabhu Pandiyan
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
| | - Xiaoyun Jiang
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
| | - Aiden Maloney-Bertelli
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
| | - James A Kuchenbecker
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
| | - Utkarsh Sharma
- Catapult Sky LLC, 34116 Blue Heron Dr, Solon, OH 44139, USA
| | - Ramkumar Sabesan
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
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Azimipour M, Valente D, Vienola KV, Werner JS, Zawadzki RJ, Jonnal RS. Optoretinogram: optical measurement of human cone and rod photoreceptor responses to light. OPTICS LETTERS 2020; 45:4658-4661. [PMID: 32870829 PMCID: PMC7891461 DOI: 10.1364/ol.398868] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 07/21/2020] [Indexed: 05/18/2023]
Abstract
Noninvasive, objective measurement of rod function is as significant as that of cone function, and for retinal diseases such as retinitis pigmentosa and age-related macular degeneration, rod function may be a more sensitive biomarker of disease progression and efficacy of treatment than cone function. Functional imaging of single human rod photoreceptors, however, has proven difficult because their small size and rapid functional response pose challenges for the resolution and speed of the imaging system. Here, we describe light-evoked, functional responses of human rods and cones, measured noninvasively using a synchronized adaptive optics optical coherence tomography (OCT) and scanning light ophthalmoscopy (SLO) system. The higher lateral resolution of the SLO images made it possible to confirm the identity of rods in the corresponding OCT volumes.
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Affiliation(s)
- Mehdi Azimipour
- Vision Science and Advanced Retinal Imaging Laboratory (VSRI), Department of Ophthalmology and Vision Science, UC Davis Eye Center, Sacramento, California 95817, USA
| | - Denise Valente
- Vision Science and Advanced Retinal Imaging Laboratory (VSRI), Department of Ophthalmology and Vision Science, UC Davis Eye Center, Sacramento, California 95817, USA
| | - Kari V. Vienola
- Vision Science and Advanced Retinal Imaging Laboratory (VSRI), Department of Ophthalmology and Vision Science, UC Davis Eye Center, Sacramento, California 95817, USA
| | - John S. Werner
- Vision Science and Advanced Retinal Imaging Laboratory (VSRI), Department of Ophthalmology and Vision Science, UC Davis Eye Center, Sacramento, California 95817, USA
| | - Robert J. Zawadzki
- Vision Science and Advanced Retinal Imaging Laboratory (VSRI), Department of Ophthalmology and Vision Science, UC Davis Eye Center, Sacramento, California 95817, USA
- EyePod Small Animal Ocular Imaging Laboratory, Department of Cell Biology and Human Anatomy, University of California Davis, Davis, California 95616, USA
| | - Ravi S. Jonnal
- Vision Science and Advanced Retinal Imaging Laboratory (VSRI), Department of Ophthalmology and Vision Science, UC Davis Eye Center, Sacramento, California 95817, USA
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