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Taskin HO, Wivel J, Aguirre GD, Beltran WA, Aguirre GK. Cone-Driven, Geniculocortical Responses in Canine Models of Outer Retinal Disease. Transl Vis Sci Technol 2024; 13:18. [PMID: 38241039 PMCID: PMC10807495 DOI: 10.1167/tvst.13.1.18] [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: 09/25/2023] [Accepted: 12/20/2023] [Indexed: 01/23/2024] Open
Abstract
Purpose Canine models of inherited retinal degeneration are used for proof of concept of emerging gene and cell-based therapies that aim to produce functional restoration of cone-mediated vision. We examined functional magnetic resonance imaging (MRI) measures of the postretinal response to cone-directed stimulation in wild-type (WT) dogs, and in three different retinal disease models. Methods Temporal spectral modulation of a uniform field of light around a photopic background was used to target the canine L/M (hereafter "L") and S cones and rods. Stimuli were designed to separately target the postreceptoral luminance (L+S) and chrominance (L-S) pathways, the rods, and all photoreceptors jointly (light flux). These stimuli were presented to WT, and mutant PDE6B-RCD1, RPGR-XLPRA2, and NPHP5-CRD2 dogs during pupillometry and functional MRI (fMRI). Results Pupil responses in WT dogs to light flux, L+S, and rod-directed stimuli were consistent with responses being driven by cone signals alone. For WT animals, both luminance and chromatic (L-S) stimuli evoked fMRI responses in the lateral geniculate nucleus or visual cortex; RCD1 animals with predominant rod loss had similar responses. Responses to cone-directed stimulation were reduced in XLPRA2 and absent in CRD2. NPHP5 gene augmentation restored the cortical response to luminance stimulation in a CRD2 animal. Conclusions Cone-directed stimulation during fMRI can be used to measure the integrity of luminance and chrominance responses in the dog visual system. The NPHP5-CRD2 model is appealing for studies of recovered cone function. Translational Relevance fMRI assessment of cone-driven cortical response provides a tool to translate cell/gene therapies for vision restoration.
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Affiliation(s)
- Huseyin O. Taskin
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Jacqueline Wivel
- Division of Experimental Retinal Therapies, Department of Clinical Sciences & Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Gustavo D. Aguirre
- Division of Experimental Retinal Therapies, Department of Clinical Sciences & Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - William A. Beltran
- Division of Experimental Retinal Therapies, Department of Clinical Sciences & Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Geoffrey K. Aguirre
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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Taskin HO, Wivel J, Aguirre GD, Beltran WA, Aguirre GK. Cone-driven, geniculo-cortical responses in canine models of outer retinal disease. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.13.571523. [PMID: 38168165 PMCID: PMC10760074 DOI: 10.1101/2023.12.13.571523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Purpose Canine models of inherited retinal degeneration are used for proof-of-concept of emerging gene and cell-based therapies that aim to produce functional restoration of cone-mediated vision. We examined functional MRI measures of the post-retinal response to cone-directed stimulation in wild type (WT) dogs, and in three different retinal disease models. Methods Temporal spectral modulation of a uniform field of light around a photopic background was used to target the canine L/M (hereafter "L") and S cones and rods. Stimuli were designed to separately target the post-receptoral luminance (L+S) and chrominance (L-S) pathways, the rods, and all photoreceptors jointly (light flux). These stimuli were presented to WT, and mutant PDE6B-RCD1, RPGR-XLPRA2, and NPHP5-CRD2 dogs during pupillometry and fMRI. Results Pupil responses in WT dogs to light flux, L+S, and rod-directed stimuli were consistent with responses being driven by cone signals alone. For WT animals, both luminance and chromatic (L-S) stimuli evoked fMRI responses in the lateral geniculate nucleus (LGN) or visual cortex; RCD1 animals with predominant rod loss had similar responses. Responses to cone-directed stimulation were reduced in XLPRA2 and absent in CRD2. NPHP5 gene augmentation restored the cortical response to luminance stimulation in a CRD2 animal. Conclusions Cone-directed stimulation during fMRI can be used to measure the integrity of luminance and chrominance responses in the dog visual system. The NPHP5-CRD2 model is appealing for studies of recovered cone function. Translational Relevance fMRI assessment of cone driven cortical response provides a tool to translate cell/gene therapies for vision restoration.
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Affiliation(s)
- Huseyin O. Taskin
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Jacqueline Wivel
- Division of Experimental Retinal Therapies, Department of Clinical Sciences & Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Gustavo D. Aguirre
- Division of Experimental Retinal Therapies, Department of Clinical Sciences & Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - William A. Beltran
- Division of Experimental Retinal Therapies, Department of Clinical Sciences & Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Geoffrey K. Aguirre
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
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Fischer J, van der Merwe J, Vandenheever D. The influence of eye model parameter variations on simulated eye-tracking outcomes. J Eye Mov Res 2023; 11:10.16910/jemr.16.3.1. [PMID: 38116296 PMCID: PMC10730094 DOI: 10.16910/jemr.16.3.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2023] Open
Abstract
The simulated data used in eye-tracking-related research has been largely generated using normative eye models with little consideration of how the variations in eye biometry found in the population may influence eye-tracking outcomes. This study investigated the influence that variations in eye model parameters have on the ability of simulated data to predict real-world eye-tracking outcomes. The real-world experiments performed by two pertinent comparative studies were replicated in a simulated environment using a highcomplexity stochastic eye model that includes anatomically accurate distributions of eye biometry parameters. The outcomes showed that variations in anterior corneal asphericity significantly influence simulated eye-tracking outcomes of both interpolation and model-based gaze estimation algorithms. Other, more commonly varied parameters such as the corneal radius of curvature and foveal offset angle had little influence on simulated outcomes.
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Lee S, Jeong J, Kim N, Shin M, Kim S. Improving Performance of the Human Pupil Orbit Model (HPOM) Estimation Method for Eye-Gaze Tracking. SENSORS (BASEL, SWITZERLAND) 2022; 22:9398. [PMID: 36502099 PMCID: PMC9737162 DOI: 10.3390/s22239398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 11/30/2022] [Accepted: 12/01/2022] [Indexed: 06/17/2023]
Abstract
Eye-gaze direction-tracking technology is used in fields such as medicine, education, engineering, and gaming. Stability, accuracy, and precision of eye-gaze direction-tracking are demanded with simultaneous upgrades in response speed. In this study, a method is proposed to improve the speed with decreases in the system load and precision in the human pupil orbit model (HPOM) estimation method. The new method was proposed based on the phenomenon that the minor axis of the elliptical-deformed pupil always pointed toward the rotational center presented in various eye-gaze direction detection studies and HPOM estimation methods. Simulation experimental results confirmed that the speed was improved by at least 74 times by consuming less than 7 ms compared to the HPOM estimation. The accuracy of the eye's ocular rotational center point showed a maximum error of approximately 0.2 pixels on the x-axis and approximately 8 pixels on the y-axis. The precision of the proposed method was 0.0 pixels when the number of estimation samples (ES) was 7 or less, which showed results consistent with those of the HPOM estimation studies. However, the proposed method was judged to work conservatively against the allowable angle error (AAE), considering that the experiment was conducted under the worst conditions and the cost used to estimate the final model. Therefore, the proposed method could estimate HPOM with high accuracy and precision through AAE adjustment according to system performance and the usage environment.
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Affiliation(s)
- Seungbong Lee
- Department of Medical Biotechnology, Dongguk University Biomedi Campus, 32, Dongguk-ro, Ilsan dong-gu, Goyang-si 10326, Republic of Korea
| | - Jaehoon Jeong
- Medical Device Industry Program in Graduate School, Dongguk University, 30, Pildong-ro 1-gill, Jung-gu, Seoul 04620, Republic of Korea
| | - Nahyun Kim
- Department of Medical Biotechnology, Dongguk University Biomedi Campus, 32, Dongguk-ro, Ilsan dong-gu, Goyang-si 10326, Republic of Korea
| | - Manjae Shin
- Department of Medical Biotechnology, Dongguk University Biomedi Campus, 32, Dongguk-ro, Ilsan dong-gu, Goyang-si 10326, Republic of Korea
| | - Sungmin Kim
- Department of Medical Biotechnology, Dongguk University Biomedi Campus, 32, Dongguk-ro, Ilsan dong-gu, Goyang-si 10326, Republic of Korea
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Taskin HO, Qiao Y, Sydnor VJ, Cieslak M, Haggerty EB, Satterthwaite TD, Morgan JI, Shi Y, Aguirre GK. Retinal ganglion cell endowment is correlated with optic tract fiber cross section, not density. Neuroimage 2022; 260:119495. [PMID: 35868617 PMCID: PMC10362491 DOI: 10.1016/j.neuroimage.2022.119495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 06/27/2022] [Accepted: 07/19/2022] [Indexed: 11/30/2022] Open
Abstract
There is substantial variation between healthy individuals in the number of retinal ganglion cells (RGC) in the eye, with commensurate variation in the number of axons in the optic tracts. Fixel-based analysis of diffusion MR produces estimates of fiber density (FD) and cross section (FC). Using these fixel measurements along with retinal imaging, we asked if individual differences in RGC tissue volume are correlated with individual differences in FD and FC measurements obtained from the optic tracts, and subsequent structures along the cortical visual pathway. We find that RGC endowment is correlated with optic tract FC, but not with FD. RGC volume had a decreasing relationship with measurements from subsequent regions of the visual system (LGN volume, optic radiation FC/FD, and V1 surface area). However, we also found that the variations in each visual area were correlated with the variations in its immediately adjacent visual structure. We only observed these serial correlations when FC is used as the measure of interest for the optic tract and radiations, but no significant relationship was found when FD represented these white matter structures. From these results, we conclude that the variations in RGC endowment, LGN volume, and V1 surface area are better predicted by the overall cross section of the optic tract and optic radiations as compared to the intra-axonal restricted signal component of these white matter pathways. Additionally, the presence of significant correlations between adjacent, but not distant, anatomical structures suggests that there are multiple, local sources of anatomical variation along the visual pathway.
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Affiliation(s)
- Huseyin O Taskin
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Yuchuan Qiao
- Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033
| | - Valerie J Sydnor
- Biomedical Graduate Studies, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Matthew Cieslak
- Department of Neuropsychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Edda B Haggerty
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Theodore D Satterthwaite
- Department of Psychiatry, Penn Lifespan Informatics and Neuroimaging Center, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Jessica Iw Morgan
- Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Yonggang Shi
- Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033
| | - Geoffrey K Aguirre
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104.
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Go CC, Taskin HO, Ahmadi SA, Frazzetta G, Cutler L, Malhotra S, Morgan JI, Flanagin VL, Aguirre GK. Persistent horizontal and vertical, MR-induced nystagmus in resting state Human Connectome Project data. Neuroimage 2022; 255:119170. [PMID: 35367649 DOI: 10.1016/j.neuroimage.2022.119170] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 03/28/2022] [Accepted: 03/30/2022] [Indexed: 10/18/2022] Open
Abstract
OBJECTIVE Strong magnetic fields from magnetic resonance (MR) scanners induce a Lorentz force that contributes to vertigo and persistent nystagmus. Prior studies have reported a predominantly horizontal direction for healthy subjects in a 7 Tesla (T) MR scanner, with slow phase velocity (SPV) dependent on head orientation. Less is known about vestibular signal behavior for subjects in a weaker, 3T magnetic field, the standard strength used in the Human Connectome Project (HCP). The purpose of this study is to characterize the form and magnitude of nystagmus induced at 3T. METHODS Forty-two subjects were studied after being introduced head-first, supine into a Siemens Prisma 3T scanner. Eye movements were recorded in four separate acquisitions over 20 minutes. A biometric eye model was fitted to the recordings to derive rotational eye position and then SPV. An anatomical template of the semi-circular canals was fitted to the T2 anatomical image from each subject, and used to derive the angle of the B0 magnetic field with respect to the vestibular apparatus. RESULTS Recordings from 37 subjects yielded valid measures of eye movements. The population-mean SPV ± SD for the horizontal component was -1.38 ± 1.27 deg/sec, and vertical component was -0.93 ± 1.44 deg/sec, corresponding to drift movement in the rightward and downward direction. Although there was substantial inter-subject variability, persistent nystagmus was present in half of subjects with no significant adaptation over the 20 minute scanning period. The amplitude of vertical drift was correlated with the roll angle of the vestibular system, with a non-zero vertical SPV present at a 0 degree roll. INTERPRETATION Non-habituating vestibular signals of varying amplitude are present in resting state data collected at 3T.
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Affiliation(s)
- Cammille C Go
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Huseyin O Taskin
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Seyed-Ahmad Ahmadi
- NVIDIA GmbH, Einsteinstraße 172, 81677 Munich, Germany; German Center for Vertigo and Balance Disorders, LMU Klinikum, 81377, Munich, Germany
| | - Giulia Frazzetta
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Laura Cutler
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Saguna Malhotra
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jessica Iw Morgan
- Department of Ophthalmology, Scheie Eye Institute, Penn Presbyterian Medical Center, 51 N 39th St, Philadelphia, PA 19104, USA
| | - Virginia L Flanagin
- German Center for Vertigo and Balance Disorders, LMU Klinikum, 81377, Munich, Germany
| | - Geoffrey K Aguirre
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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Kaiser EA, McAdams H, Igdalova A, Haggerty EB, Cucchiara BL, Brainard DH, Aguirre GK. Reflexive Eye Closure in Response to Cone and Melanopsin Stimulation: A Study of Implicit Measures of Light Sensitivity in Migraine. Neurology 2021; 97:e1672-e1680. [PMID: 34493620 DOI: 10.1212/wnl.0000000000012734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 08/16/2021] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND AND OBJECTIVES To quantify interictal photophobia in migraine with and without aura using reflexive eye closure as an implicit measure of light sensitivity and to assess the contribution of melanopsin and cone signals to these responses. METHODS Participants were screened to meet criteria for 1 of 3 groups: headache-free (HF) controls, migraine without aura (MO), and migraine with visual aura (MA). MO and MA participants were included if they endorsed ictal and interictal photophobia. Exclusion criteria included impaired vision, inability to collect usable pupillometry, and history of either head trauma or seizure. Participants viewed light pulses that selectively targeted melanopsin, the cones, or their combination during recording of orbicularis oculi EMG (OO-EMG) and blinking activity. RESULTS We studied 20 participants in each group. MA and MO groups reported increased visual discomfort to light stimuli (discomfort rating, 400% contrast, MA: 4.84 [95% confidence interval 0.33, 9.35]; MO: 5.23 [0.96, 9.50]) as compared to HF controls (2.71 [0, 6.47]). Time course analysis of OO-EMG and blinking activity demonstrated that reflexive eye closure was tightly coupled to the light pulses. The MA group had greater OO-EMG and blinking activity in response to these stimuli (EMG activity, 400% contrast: 42.9%Δ [28.4, 57.4]; blink activity, 400% contrast: 11.2% [8.8, 13.6]) as compared to the MO (EMG activity, 400% contrast: 9.9%Δ [5.8, 14.0]; blink activity, 400% contrast: 4.7% [3.5, 5.9]) and HF control (EMG activity, 400% contrast: 13.2%Δ [7.1, 19.3]; blink activity, 400% contrast: 4.5% [3.1, 5.9]) groups. DISCUSSION Our findings suggest that the intrinsically photosensitive retinal ganglion cells (ipRGCs), which integrate melanopsin and cone signals, provide the afferent input for light-induced reflexive eye closure in a photophobic state. Moreover, we find a dissociation between implicit and explicit measures of interictal photophobia depending on a history of visual aura in migraine. This implies distinct pathophysiology in forms of migraine, interacting with separate neural pathways by which the amplification of ipRGC signals elicits implicit and explicit signs of visual discomfort.
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Affiliation(s)
- Eric A Kaiser
- From the Departments of Neurology (E.A.K., A.I., E.B.H., B.L.C., G.K.A.) and Neuroscience (H.M.), Perelman School of Medicine, and Department of Psychology (D.H.B.), University of Pennsylvania, Philadelphia.
| | - Harrison McAdams
- From the Departments of Neurology (E.A.K., A.I., E.B.H., B.L.C., G.K.A.) and Neuroscience (H.M.), Perelman School of Medicine, and Department of Psychology (D.H.B.), University of Pennsylvania, Philadelphia
| | - Aleksandra Igdalova
- From the Departments of Neurology (E.A.K., A.I., E.B.H., B.L.C., G.K.A.) and Neuroscience (H.M.), Perelman School of Medicine, and Department of Psychology (D.H.B.), University of Pennsylvania, Philadelphia
| | - Edda B Haggerty
- From the Departments of Neurology (E.A.K., A.I., E.B.H., B.L.C., G.K.A.) and Neuroscience (H.M.), Perelman School of Medicine, and Department of Psychology (D.H.B.), University of Pennsylvania, Philadelphia
| | - Brett L Cucchiara
- From the Departments of Neurology (E.A.K., A.I., E.B.H., B.L.C., G.K.A.) and Neuroscience (H.M.), Perelman School of Medicine, and Department of Psychology (D.H.B.), University of Pennsylvania, Philadelphia
| | - David H Brainard
- From the Departments of Neurology (E.A.K., A.I., E.B.H., B.L.C., G.K.A.) and Neuroscience (H.M.), Perelman School of Medicine, and Department of Psychology (D.H.B.), University of Pennsylvania, Philadelphia
| | - Geoffrey K Aguirre
- From the Departments of Neurology (E.A.K., A.I., E.B.H., B.L.C., G.K.A.) and Neuroscience (H.M.), Perelman School of Medicine, and Department of Psychology (D.H.B.), University of Pennsylvania, Philadelphia
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Abstract
Pupillometry - the study of temporal changes in pupil diameter as a function of external light stimuli or cognitive processing - requires the accurate and gaze-angle independent measurement of pupil dilation. Expected response amplitudes often are only a few percent relative to a pre-stimulus baseline, thus demanding for sub-millimeter accuracy. Video-based approaches to pupil-size measurement aim at inferring pupil dilation from eye images alone. Eyeball rotation in relation to the recording camera as well as optical effects due to refraction at corneal interfaces can, however, induce so-called pupil foreshortening errors (PFE), i.e. systematic gaze-angle dependent changes of apparent pupil size that are on a par with typical response amplitudes. While PFE and options for its correction have been discussed for remote eye trackers, for head-mounted eye trackers such an assessment is still lacking. In this work, we therefore gauge the extent of PFE in three measurement techniques, all based on eye images recorded with a single near-eye camera. We present both real world experimental data as well as results obtained on synthetically generated eye images. We discuss PFE effects at three different levels of data aggregation: the sample, subject, and population level. In particular, we show that a recently proposed refraction-aware approach employing a mathematical 3D eye model is successful in providing pupil-size measurements which are gaze-angle independent at the population level.
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Spaccapaniccia C, Via R, Thominet V, Liffey A, Baroni G, Pica A, Weber DC, Lomax AJ, Hrbacek J. Non-invasive recognition of eye torsion through optical imaging of the iris pattern in ocular proton therapy. Phys Med Biol 2021; 66. [PMID: 34126607 DOI: 10.1088/1361-6560/ac0afb] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 06/14/2021] [Indexed: 11/12/2022]
Abstract
The introduction of non-invasive imaging techniques such as MRI imaging for treatment planning and optical eye tracking for in-room eye localization would obviate the requirement of clips implantation for many patients undergoing ocular proton therapy. This study specifically addresses the issue of torsional eye movement detection during patient positioning. Non-invasive detection of eye torsion is performed by measuring the iris pattern rotations using a beams eye view optical camera. When handling images of patients to be treated using proton therapy, a number of additional challenges are encountered, such as changing eye position, pupil dilatation and illumination. A method is proposed to address these extra challenges while also compensating for the effect of cornea distortion in eye torsion computation. The accuracy of the proposed algorithm was evaluated against corresponding measurement of eye torsion using the clips configuration measured on x-ray images. This study involves twenty patients who received ocular proton therapy at Paul Scherrer Institute and it is covered by ethical approval (EKNZ 2019-01987).
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The pupil-size artefact (PSA) across time, viewing direction, and different eye trackers. Behav Res Methods 2021; 53:1986-2006. [PMID: 33709298 PMCID: PMC8516786 DOI: 10.3758/s13428-020-01512-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/09/2020] [Indexed: 11/15/2022]
Abstract
The pupil size artefact (PSA) is the gaze deviation reported by an eye tracker during pupil size changes if the eye does not rotate. In the present study, we ask three questions: 1) how stable is the PSA over time, 2) does the PSA depend on properties of the eye tracker set up, and 3) does the PSA depend on the participants’ viewing direction? We found that the PSA is very stable over time for periods as long as 1 year, but may differ between participants. When comparing the magnitude of the PSA between eye trackers, we found the magnitude of the obtained PSA to be related to the direction of the eye-tracker-camera axis, suggesting that the angle between the participants’ viewing direction and the camera axis affects the PSA. We then investigated the PSA as a function of the participants’ viewing direction. The PSA was non-zero for viewing direction 0∘ and depended on the viewing direction. These findings corroborate the suggestion by Choe et al. (Vision Research 118(6755):48–59, 2016), that the PSA can be described by an idiosyncratic and a viewing direction-dependent component. Based on a simulation, we cannot claim that the viewing direction-dependent component of the PSA is caused by the optics of the cornea.
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Chen M, Nofziger J, Datta R, Gee JC, Morgan J, Aguirre GK. The Influence of Axial Length Upon the Retinal Ganglion Cell Layer of the Human Eye. Transl Vis Sci Technol 2020; 9:9. [PMID: 33344053 PMCID: PMC7726585 DOI: 10.1167/tvst.9.13.9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 10/04/2020] [Indexed: 11/24/2022] Open
Abstract
Purpose Variation in retinal thickness with eye size complicates efforts to estimate retinal ganglion cell number from optical coherence tomography (OCT) measures. We examined the relationship among axial length, the thickness and volume of the ganglion cell layer (GCL), and the size of the optic chiasm. Methods We used OCT to measure GCL thickness over 50 degrees of the horizontal meridian in 50 healthy participants with a wide range of axial lengths. Using a model eye informed by individual biometry, we converted GCL thickness to tissue volume per square degree. We also measured the volume of the optic chiasm for 40 participants using magnetic resonance imaging (MRI). Results There is a positive relationship between GCL tissue volume and axial length. Given prior psychophysical results, we conclude that increased axial length is associated with increased retinal ganglion cell size, decreased cell packing, or both. We characterize how retinal ganglion cell tissue varies systematically in volume and spatial distribution as a function of axial length. This model allows us to remove the effect of axial length from individual difference measures of GCL volume. We find that variation in this adjusted GCL volume correlates well with the size of the optic chiasm. Conclusions Our results provide the volume of ganglion cell tissue in the retina, adjusted for the presumed effects of axial length upon ganglion cell size and/or packing. The resulting volume measure accounts for individual differences in the size of the optic chiasm, supporting its use to characterize the post-retinal visual pathway. Translational Relevance Variations in ametropia can confound clinical measures of retinal features. We present a framework within which the thickness and volume of retinal structures can be measured and corrected for the effects of axial length.
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Affiliation(s)
- Min Chen
- Department of Radiology, Scheie Eye Institute, Penn Presbyterian Medical Center, Philadelphia, PA, USA
| | - Jill Nofziger
- Department of Neurology, Scheie Eye Institute, Penn Presbyterian Medical Center, Philadelphia, PA, USA
| | - Ritobrato Datta
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - James C Gee
- Department of Radiology, Scheie Eye Institute, Penn Presbyterian Medical Center, Philadelphia, PA, USA
| | - Jessica Morgan
- Department of Ophthalmology, Scheie Eye Institute, Penn Presbyterian Medical Center, Philadelphia, PA, USA.,Center for Retinal and Ocular Therapeutics Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Geoffrey K Aguirre
- Department of Neurology, Scheie Eye Institute, Penn Presbyterian Medical Center, Philadelphia, PA, USA
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