Imaging performance of portable and conventional ultrasound imaging technologies for ophthalmic applications

PURPOSE

The aim of this study was to evaluate the imaging capabilities of Butterfly iQ with conventional ophthalmic (piezoelectric) ultrasound (COU) for ophthalmic imaging.

METHODS

Custom phantom molds were designed and imaged with Butterfly iQ and COU to compare spatial resolution capabilities. To evaluate the clinical imaging performance of Butterfly iQ and COU, a survey containing pathological conditions from human subjects, imaged with both Butterfly iQ and COU probes, was given to three retina specialists and graded on image detail, resolution, quality, and diagnostic confidence on a ten-point Likert scale. Kruskal-Wallis analysis was performed for survey responses.

RESULTS

Butterfly iQ and COU had comparable capabilities for imaging small axial and lateral phantom features (down to 0.1 mm) of high and low acoustic reflectivity. One of three retina specialists demonstrated a statistically significant preference for COU related to resolution, detail, and diagnostic confidence, but the remaining graders showed no significant preference for Butterfly iQ or COU across all sample images presented.

CONCLUSION

The emergence of portable ultrasound probes offers an affordable alternative to COU technologies with comparable qualitative imaging resolution down to 0.1 mm. These findings suggest the value to further study the use of portable ultrasound systems and their utility in routine eye care.

Deep Learning Assisted Imaging Methods to Facilitate Access to Ophthalmic Telepathology

Purpose

To investigate the use of super-resolution imaging techniques to enable telepathology using low-cost commercial cameras.

Design

Experimental study.

Participants

A total of 139 ophthalmic pathology slides obtained from the Ophthalmic Pathology service at the University of California, Irvine.

Methods

Denoising Diffusion Probabilistic Model (DDPM) was developed to predict super-resolution pathology slide images from low-resolution inputs. The model was pretrained using 150 000 images randomly sampled from the ImageNet dataset. Patch aggregation was used to generate large images with DDPM. The performance of DDPM was evaluated against that of generative adversarial networks (GANs) and Robust UNet, which were also trained on the same dataset.

Main Outcome Measures

The performance of models trained to generate super-resolution output images from low-resolution input images can be evaluated by using the mean squared error (MSE) and Structural Similarity Index Measure (SSIM), as well as subjective grades provided by expert pathologist graders.

Results

In total, our study included 110 training images, 9 validation images, and 20 testing images. The objective performance scores were averaged over patches generated from 20 test images. The DDPM-based approach with pretraining produced the best results, with an MSE score of 1.35e-5 and an SSIM score of 0.8987. A qualitative analysis of super-resolution images was conducted by expert 3 pathologists and 1 expert ophthalmic microscopist, and the average accuracy of identifying the correct ground truth images ranged from 25% to 70% (with an average accuracy of 46.5%) for widefield images and 25% to 60% (with an average accuracy of 38.25%) for individual patches.

Conclusions

The DDPM-based approach with pretraining is assessed to be effective at super-resolution prediction for ophthalmic pathology slides both in terms of objective and subjective measures. The proposed methodology is expected to decrease the reliance on costly slide scanners for acquiring high-quality pathology slide images, while also streamlining clinical workflow and expanding the scope of ophthalmic telepathology.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Genome editing in the treatment of ocular diseases

Genome-editing technologies have ushered in a new era in gene therapy, providing novel therapeutic strategies for a wide range of diseases, including both genetic and nongenetic ocular diseases. These technologies offer new hope for patients suffering from previously untreatable conditions. The unique anatomical and physiological features of the eye, including its immune-privileged status, size, and compartmentalized structure, provide an optimal environment for the application of these cutting-edge technologies. Moreover, the development of various delivery methods has facilitated the efficient and targeted administration of genome engineering tools designed to correct specific ocular tissues. Additionally, advancements in noninvasive ocular imaging techniques and electroretinography have enabled real-time monitoring of therapeutic efficacy and safety. Herein, we discuss the discovery and development of genome-editing technologies, their application to ocular diseases from the anterior segment to the posterior segment, current limitations encountered in translating these technologies into clinical practice, and ongoing research endeavors aimed at overcoming these challenges.

Optimization of a Novel Automated, Low Cost, Three-Dimensional Photogrammetry System (PHACE)

Introduction

Clinical tools are neither standardized nor ubiquitous to monitor volumetric or morphological changes in the periorbital region and ocular adnexa due to pathology such as oculofacial trauma, thyroid eye disease, and the natural aging process. We have developed a low-cost, three dimensionally printed PHotogrammetry for Automated CarE (PHACE) system to evaluate three-dimensional (3D) measurements of periocular and adnexal tissue.

Methods

The PHACE system uses two Google Pixel 3 smartphones attached to automatic rotating platforms to image a subject's face through a cutout board patterned with registration marks. Photographs of faces were taken from many perspectives by the cameras placed on the rotating platform. Faces were imaged with and without 3D printed hemispheric phantom lesions (black domes) affixed on the forehead above the brow. Images were rendered into 3D models in Metashape (Agisoft, St. Petersburg, Russia) and then processed and analyzed in CloudCompare (CC) and Autodesk's Meshmixer. The 3D printed hemispheres affixed to the face were then quantified within Meshmixer and compared to their known volumes. Finally, we compared digital exophthalmometry measurements with results from a standard Hertel exophthalmometer in a subject with and without an orbital prosthesis.

Results

Quantification of 3D printed phantom volumes using optimized stereophotogrammetry demonstrated a 2.5% error for a 244μL phantom, and 7.6% error for a 27.5μL phantom. Digital exophthalmometry measurements differed by 0.72mm from a standard exophthalmometer.

Conclusion

We demonstrated an optimized workflow using our custom apparatus to analyze and quantify oculofacial volumetric and dimensions changes with a resolution of 244μL. This apparatus is a low-cost tool that can be used in clinical settings to objectively monitor volumetric and morphological changes in periorbital anatomy.

Comparison of a custom Photogrammetry for Anatomical CarE (PHACE) system with other Low- Cost Facial Scanning Devices

Purpose

To compare a custom Photogrammetry for Anatomical CarE (PHACE) system with other cost-effective 3-dimensional (3D) facial scanning systems to objectively characterize morphology and volume of periorbital and adnexal anatomy.

Methods

The imaging systems evaluated include the low-cost custom PHACE system and commercial software product for the iPhone called Scandy Pro (iScandy) application (Scandy, USA), and the mid-priced Einscan Pro 2X (Shining3D Technologies, China) device and Array of Reconstructed Cameras 7 (ARC7) facial scanner (Bellus3D, USA). Imaging was performed on a manikin facemask and humans with various Fitzpatrick scores. Scanner attributes were assessed using mesh density, reproducibility, surface deviation, and emulation of 3D printed phantom lesions affixed above the superciliary arch (brow line).

Results

The Einscan served as a reference for lower cost imaging systems because it qualitatively and quantitatively renders facial morphology with the highest mesh density, reproducibility (0.13 ± 0.10 mm), and volume recapitulation (approximately 2% of 33.5 μL). Compared to the Einscan, the PHACE system (0.35 ± 0.03 mm, 0.33 ± 0.16 mm) demonstrated non-inferior mean accuracy and reproducibility root mean square (RMS) compared to the iScandy (0.42 ± 0.13 mm, 0.58 ± 0.09 mm), and significantly more expensive ARC7 (0.42 ± 0.03 mm, 0.26 ± 0.09 mm). Similarly, the PHACE system showed non-inferior volumetric modeling when rendering a 124 μL phantom lesion compared to the iScandy and more costly ARC7 (mean percent difference from the Einscan: 4.68 ± 3.73%, 9.09 ± 0.94%, and 21.99 ± 17.91% respectively).

Conclusions

The affordable PHACE system accurately measures periorbital soft tissue as well as other established mid-cost facial scanning systems. Additionally, the portability, affordability, and adaptability of PHACE can facilitate widespread adoption of 3D facial anthropometric technology as an objective measurement tool in ophthalmology.

Quantitative cone contrast threshold testing in patients with differing pathophysiological mechanisms causing retinal diseases

BACKGROUND

Cone contrast threshold testing (CCT) provides quantitative measurements of color and contrast function to reveal changes in vision quality that are not standard endpoints in clinical trials. We utilize CCT to measure visual function in patients with multiple sclerosis (MS), age-related macular degeneration (AMD), epiretinal membrane (ERM), and retinal vein occlusion (RVO).

METHODS

Retrospective data was gathered from 237 patients of the Gavin Herbert Eye Institute. Subjects included 17 patients with MS, 45 patients with AMD, 41 patients with ERM, 11 patients with RVO, and 123 healthy controls. Patients underwent the primary measurement outcome, CCT testing, as well as Sloan visual acuity test and spectral domain optical coherence tomography during normal care.

RESULTS

Color and contrast deficits were present in MS patients regardless of history of optic neuritis. AMD with intermediate or worse disease demonstrated reduced CCT scores. All 3 stages of ERM demonstrated cone contrast deficits. Despite restoration of visual acuity, RVO-affected eyes demonstrated poorer CCT performance than unaffected fellow eyes.

CONCLUSIONS

CCT demonstrates color and contrast deficits for multiple retinal diseases with differing pathophysiology. Further prospective studies of CCT in other disease states and with larger samples sizes is warranted.

Vitreoretinal Surgical Instrument Tracking in Three Dimensions Using Deep Learning

Purpose

To evaluate the potential for artificial intelligence-based video analysis to determine surgical instrument characteristics when moving in the three-dimensional vitreous space.

Methods

We designed and manufactured a model eye in which we recorded choreographed videos of many surgical instruments moving throughout the eye. We labeled each frame of the videos to describe the surgical tool characteristics: tool type, location, depth, and insertional laterality. We trained two different deep learning models to predict each of the tool characteristics and evaluated model performances on a subset of images.

Results

The accuracy of the classification model on the training set is 84% for the x-y region, 97% for depth, 100% for instrument type, and 100% for laterality of insertion. The accuracy of the classification model on the validation dataset is 83% for the x-y region, 96% for depth, 100% for instrument type, and 100% for laterality of insertion. The close-up detection model performs at 67 frames per second, with precision for most instruments higher than 75%, achieving a mean average precision of 79.3%.

Conclusions

We demonstrated that trained models can track surgical instrument movement in three-dimensional space and determine instrument depth, tip location, instrument insertional laterality, and instrument type. Model performance is nearly instantaneous and justifies further investigation into application to real-world surgical videos.

Translational Relevance

Deep learning offers the potential for software-based safety feedback mechanisms during surgery or the ability to extract metrics of surgical technique that can direct research to optimize surgical outcomes.

Seeing invisible light: 2-photon microperimetry to measure visual function

Purpose

The accuracy of conventional visual function tests, which emit visible light, decreases in patients with corneal scars, cataracts, and vitreous hemorrhages. In contrast, infrared (IR) light exhibits greater tissue penetrance than visible light and is less susceptible to optical opacities. We therefore compared conventional visual function tests against infrared 2-phton microperimetry (2PM-IR) in a subject with a brunescent nuclear sclerotic and posterior subcapsular cataract before and after cataract surgery.

Methods

Testing using infrared light microperimetry from a novel device (2PM-IR), visible light microperimetry from a novel device (2PM-Vis), conventional microperimetry, and the cone contrast threshold (CCT) test were performed before and after cataract surgery.

Results

Retinal sensitivity assessed using 2PM-IR, 2PM-Vis, and cMP improved by 3.4 dB, 17.4 dB, and 18 dB, respectively. Cone contrast threshold testing improved for the S-cone, M-cone, and l-cone by 111, 14, and 30.

Conclusions and Importance

2PM-IR, unlike conventional visual function tests, showed minimal variability in retinal sensitivity before and after surgery. Thus, IR visual stimulation may provide a more accurate means of measuring neurosensory retinal function by circumventing optical media opacities, aiding in the diagnosis of early macular disease.

The Prospects for Retinal Organoids in Treatment of Retinal Diseases

Retinal degeneration (RD) is a significant cause of incurable blindness worldwide. Photoreceptors and retinal pigmented epithelium are irreversibly damaged in advanced RD. Functional replacement of photoreceptors and/or retinal pigmented epithelium cells is a promising approach to restoring vision. This paper reviews the current status and explores future prospects of the transplantation therapy provided by pluripotent stem cell-derived retinal organoids (ROs). This review summarizes the status of rodent RD disease models and discusses RO culture and analytical tools to evaluate RO quality and function. Finally, we review and discuss the studies in which RO-derived cells or sheets were transplanted. In conclusion, methods to derive ROs from pluripotent stem cells have significantly improved and become more efficient in recent years. Meanwhile, more novel technologies are applied to characterize and validate RO quality. However, opportunity remains to optimize tissue differentiation protocols and achieve better RO reproducibility. In order to screen high-quality ROs for downstream applications, approaches such as noninvasive and label-free imaging and electrophysiological functional testing are promising and worth further investigation. Lastly, transplanted RO-derived tissues have allowed improvements in visual function in several RD models, showing promises for clinical applications in the future.

Deep learning to enable color vision in the dark

Humans perceive light in the visible spectrum (400-700 nm). Some night vision systems use infrared light that is not perceptible to humans and the images rendered are transposed to a digital display presenting a monochromatic image in the visible spectrum. We sought to develop an imaging algorithm powered by optimized deep learning architectures whereby infrared spectral illumination of a scene could be used to predict a visible spectrum rendering of the scene as if it were perceived by a human with visible spectrum light. This would make it possible to digitally render a visible spectrum scene to humans when they are otherwise in complete “darkness” and only illuminated with infrared light. To achieve this goal, we used a monochromatic camera sensitive to visible and near infrared light to acquire an image dataset of printed images of faces under multispectral illumination spanning standard visible red (604 nm), green (529 nm) and blue (447 nm) as well as infrared wavelengths (718, 777, and 807 nm). We then optimized a convolutional neural network with a U-Net-like architecture to predict visible spectrum images from only near-infrared images. This study serves as a first step towards predicting human visible spectrum scenes from imperceptible near-infrared illumination. Further work can profoundly contribute to a variety of applications including night vision and studies of biological samples sensitive to visible light.

A case report of cystoid macular edema, uveitis and vitreomacular traction in a patient taking Anastrozole

Purpose

To report a case of cystoid macular edema, uveitis, and vitreomacular traction in a patient with a history of breast cancer and taking anastrozole.

Observations

A 73-year-old female with a history of estrogen receptor-positive breast cancer and treatment with anastrozole presented with bilateral blurry vision, photophobia, and eye soreness. Optical coherence tomography (OCT) of both maculae revealed vitreomacular traction (VMT), an epiretinal membrane, cystoid macular edema (CME) in the right eye, and drusen without subretinal fluid bilaterally. Although later, macular OCT did show evidence of cystoid intraretinal spaces in the left eye as well. Fluorescein angiography showed bilateral petaloid leakage, bilateral slow disc leaking, as well as peripheral leakage in the right eye. Anastrozole was discontinued and, subsequent macular OCT showed release of VMT in the right eye, and eventual resolution of intraretinal cystoid spaces bilaterally.

Conclusions and importance

Stopping of anastrozole was associated in resolution of refractory CME in a patient on aromatase inhibitor therapy for breast cancer. It is therefore important to consider anastrozole and other aromatase inhibitor drugs as possible factors predisposing patients to the development of CME.

Treatment of Choroidal Metastasis from Epidermal Growth Factor Mutant Non-Small Cell Lung Cancer with First-line Osimertinib Therapy

Purpose

To illustrate the regression of a metastatic lesion through ophthalmic imaging and correlating findings with standard chest imaging and treatment with osimertinib, an oral chemotherapy agent specific to Epidermal Growth Factor Receptor + Non-small Cell Lung Cancer (EGFR+ NSCLC).

Case Report

A 63-year-old Asian male presented to ophthalmology with a complaint of left blurry vision. Initial ophthalmic exam revealed a choroidal lesion and imaging results highlighted a spiculated lung mass with brain and bony metastases. Osimertinib was chosen for its specificity and ability to cross the blood-brain barrier. Follow-up ophthalmic and radiographic imaging were repeated over the course of treatment.

Conclusion

After the initiation of osimertinib, ophthalmic and computed tomography imaging highlighted the regression of the ocular metastatic disease and primary malignancy, respectively.Osimertinib is an effective first-line treatment of EGFR+ NSCLC and corresponding metastatic sites. Additionally, ophthalmic imaging can be used to monitor general response to chemotherapy agents when ocular metastasis is identified.

Retinal Organoids Long-Term Functional Characterization Using Two-Photon Fluorescence Lifetime and Hyperspectral Microscopy

Pluripotent stem cell-derived organoid technologies have opened avenues to preclinical basic science research, drug discovery, and transplantation therapy in organ systems. Stem cell-derived organoids follow a time course similar to species-specific organ gestation in vivo. However, heterogeneous tissue yields, and subjective tissue selection reduce the repeatability of organoid-based scientific experiments and clinical studies. To improve the quality control of organoids, we introduced a live imaging technique based on two-photon microscopy to non-invasively monitor and characterize retinal organoids’ (RtOgs’) long-term development. Fluorescence lifetime imaging microscopy (FLIM) was used to monitor the metabolic trajectory, and hyperspectral imaging was applied to characterize structural and molecular changes. We further validated the live imaging experimental results with endpoint biological tests, including quantitative polymerase chain reaction (qPCR), single-cell RNA sequencing, and immunohistochemistry. With FLIM results, we analyzed the free/bound nicotinamide adenine dinucleotide (f/b NADH) ratio of the imaged regions and found that there was a metabolic shift from glycolysis to oxidative phosphorylation. This shift occurred between the second and third months of differentiation. The total metabolic activity shifted slightly back toward glycolysis between the third and fourth months and stayed relatively stable between the fourth and sixth months. Consistency in organoid development among cell lines and production lots was examined. Molecular analysis showed that retinal progenitor genes were expressed in all groups between days 51 and 159. Photoreceptor gene expression emerged around the second month of differentiation, which corresponded to the shift in the f/b NADH ratio. RtOgs between 3 and 6 months of differentiation exhibited photoreceptor gene expression levels that were between the native human fetal and adult retina gene expression levels. The occurrence of cone opsin expression (OPN1 SW and OPN1 LW) indicated the maturation of photoreceptors in the fourth month of differentiation, which was consistent with the stabilized level of f/b NADH ratio starting from 4 months. Endpoint single-cell RNA and immunohistology data showed that the cellular compositions and lamination of RtOgs at different developmental stages followed those in vivo.

Deep Learning-Assisted Multiphoton Microscopy to Reduce Light Exposure and Expedite Imaging in Tissues With High and Low Light Sensitivity

Purpose

Two-photon excitation fluorescence (2PEF) reveals information about tissue function. Concerns for phototoxicity demand lower light exposure during imaging. Reducing excitation light reduces the quality of the image by limiting fluorescence emission. We applied deep learning (DL) super-resolution techniques to images acquired from low light exposure to yield high-resolution images of retinal and skin tissues.

Methods

We analyzed two methods: a method based on U-Net and a patch-based regression method using paired images of skin (550) and retina (1200), each with low- and high-resolution paired images. The retina dataset was acquired at low and high laser powers from retinal organoids, and the skin dataset was obtained from averaging 7 to 15 frames or 70 frames. Mean squared error (MSE) and the structural similarity index measure (SSIM) were outcome measures for DL algorithm performance.

Results

For the skin dataset, the patches method achieved a lower MSE (3.768) compared with U-Net (4.032) and a high SSIM (0.824) compared with U-Net (0.783). For the retinal dataset, the patches method achieved an average MSE of 27,611 compared with 146,855 for the U-Net method and an average SSIM of 0.636 compared with 0.607 for the U-Net method. The patches method was slower (303 seconds) than the U-Net method (<1 second).

Conclusions

DL can reduce excitation light exposure in 2PEF imaging while preserving image quality metrics.

Translational Relevance

DL methods will aid in translating 2PEF imaging from benchtop systems to in vivo imaging of light-sensitive tissues such as the retina.

Retinal organoids on-a-chip: a micro-millifluidic bioreactor for long-term organoid maintenance

Retinal degeneration is a leading cause of vision impairment and blindness worldwide and medical care for advanced disease does not exist. Stem cell-derived retinal organoids (RtOgs) became an emerging tool for tissue replacement therapy. However, existing RtOg production methods are highly heterogeneous. Controlled and predictable methodology and tools are needed to standardize RtOg production and maintenance. In this study, we designed a shear stress-free micro-millifluidic bioreactor for nearly labor-free retinal organoid maintenance. We used a stereolithography (SLA) 3D printer to fabricate a mold from which Polydimethylsiloxane (PDMS) was cast. We optimized the chip design using in silico simulations and in vitro evaluation to optimize mass transfer efficiency and concentration uniformity in each culture chamber. We successfully cultured RtOgs at three different differentiation stages (day 41, 88, and 128) on an optimized bioreactor chip for more than 1 month. We used different quantitative and qualitative techniques to fully characterize the RtOgs produced by static dish culture and bioreactor culture methods. By analyzing the results from phase contrast microscopy, single-cell RNA sequencing (scRNA seq), quantitative polymerase chain reaction (qPCR), immunohistology, and electron microscopy, we found that bioreactor-cultured RtOgs developed cell types and morphology comparable to static cultured ones and exhibited similar retinal genes expression levels. We also evaluated the metabolic activity of RtOgs in both groups using fluorescence lifetime imaging (FLIM), and found that the outer surface region of bioreactor cultured RtOgs had a comparable free/bound NADH ratio and overall lower long lifetime species (LLS) ratio than static cultured RtOgs during imaging. To summarize, we validated an automated micro-millifluidic device with significantly reduced shear stress to produce RtOgs of comparable quality to those maintained in conventional static culture.

Two-Photon Microperimetry: A Media Opacity-Independent Retinal Function Assay

Purpose

Compare results obtained using infrared two-photon microperimetry (2PM-IR) with conventional visual function tests in healthy subjects of varying ages with and without simulated media opacities.

Methods

Subjects from two separate cohort studies completed cone contrast threshold (CCT) testing, conventional microperimetry, visible light microperimetry from a novel device (2PM-Vis), and infrared two-photon microperimetry. The first cohort study, which consisted of six healthy volunteers (23 to 29 years of age), evaluated the effects of simulated media opacities on visual performance testing. Subjects underwent testing on four visual function devices nine separate times under the following conditions: no filter, red filter, green filter, blue filter, light brown filter, dark brown filter, polarized black filter (0° rotation), and polarized black filter (90° rotation). Subjects subsequently performed 2PM-IR and 2PM-Vis testing without a filter in the mydriatic state. The second cohort study evaluated the effect of age on visual test performance in 42 healthy subjects split between two groups (ages 20-40 years and 60-80 years).

Results

Retinal sensitivity measured by 2PM-IR demonstrated lower variability than all other devices relying on visible spectrum stimuli. Retinal sensitivity decreased proportionally with the transmittance of light through each filter. CCT scores and retinal sensitivity decreased with age in all testing modalities. Visible spectrum testing modalities demonstrated larger test result differences between young and old patient cohorts; this difference was inversely proportional to the wavelength of the visual function test.

Conclusions

2PM-IR mitigates media opacities that may mask small differences in retinal sensitivity when tested with conventional visual function testing devices.

Translational Relevance

Conventional visual function tests that emit visible light may not detect differences in retinal function during the early stages of age-related diseases due to the confounding effects of cataracts. Infrared light, which has greater transmittance through ocular tissue, may reliably quantify retinal sensitivity and thereby detect degenerative changes early on.

Multimodal Imaging in Ocular Siderosis

Purpose

This report aims to characterize ocular changes in a case of ocular siderosis with iron toxicity using multimodal imaging and electroretinography.

Methods

A 34-year-old woman presented with ocular siderosis of the left eye following penetrating injury with an iron-containing foreign body. The patient's uncorrected visual acuities were 20/60 and 20/150 in the right and left eye, respectively, with abnormal pupillary function and presence of a cataract in the left eye. She underwent successful intraocular foreign body removal and cataract surgery with no postoperative complications. Cone contrast threshold (CCT), full-field electroretinogram, spectral-domain optical coherence tomography (OCT), and OCT angiography (OCTA) were used to characterize ocular alterations preoperatively and postoperatively.

Results

CCT color vision testing showed abnormal color vision, and OCTA revealed increased vascular flow density associated with the foreign body.

Conclusions

CCT color vision testing, OCTA, OCT, and full-field electroretinogram can characterize retinal changes in cases of ocular siderosis.

Quantifying Color Vision Changes Associated With Cataracts Using Cone Contrast Thresholds

Purpose

To evaluate effects of age and simulated and real cataractous changes on color vision as measured by the high-definition cone contrast test (CCT).

Methods

Twenty-four healthy volunteers from two cohort studies performed CCT using best-corrected visual acuity, filters, mydriasis, and pinhole correction. Retrospective cross-sectional study of patients seen in eye clinics evaluated the relationship between age and color vision, and age and lens status in 355 eyes. Last, 25 subjects underwent CCT before and after cataract surgery.

Results

CCT scores were most reliable in the nonmydriatic condition without pinhole correction. Progressively dense brown filters produced small decreases in S-cone sensitivity. Linear regression analysis of phakic subjects showed a decline for all cone classes with age. Rate of decline was greater for S-cones (slope = −1.09; 95% confidence interval [CI], −1.30 to 0.86) than M-cones (slope = −0.80; 95% CI, −1.03 to −0.58) and L-cones (slope = −0.66; 95% CI, −0.88 to −0.44). CCT scores increased for S-cones but reduced for L- and M-cones in pseudophakic subjects compared with phakic patients. CCT scores after cataract surgery increased for S-cones, M-cones, and L-cones by 33.0 (95% CI, 8.6 to 57.4), 24.9 (95% CI, 3.8 to 46.0), and 22.0 (95% CI, −3.2 to 47.3), respectively.

Conclusions

CCT assessment allows for clinically practical quantitation of color and contrast vision improvement after cataract surgery and aging patients who note poor vision despite good visual acuity.

Translational Relevance

CCT testing, which quantifies hereditary and acquired color deficiency, can also quantify the degree of cataract severity and, combined with other parameters, can provide more precise guidance for cataract extraction to optimize patient care.

Quantitative Analysis of Ellipsoid Zone in Acute Posterior Multifocal Placoid Pigment Epitheliopathy

Purpose:

Quantitative end points for uveitis are needed. Here we quantify the rate of ellipsoid zone (EZ) recovery on optical coherence tomography (OCT) and correlate it with visual acuity (VA) improvement in patients with acute posterior multifocal placoid pigmented epitheliopathy (APMPPE). We use automated and manually graded EZ area analysis to assess EZ recovery in APMPPE.

Methods:

We performed a retrospective review of 9 APMPPE cases (18 eyes) that had characteristic clinical examination and fluorescein angiography findings, outer retinal disruption on spectral-domain OCT, and treatment with systemic steroids after an unambiguous laboratory workup. The EZ was delineated using custom software to perform automated analysis and manual grading by 2 independent physicians. Quantitation of EZ changes was performed in ImageJ (National Institutes of Health). EZ maps were compared with equivalent findings from EZ en face OCT segmentation.

Results:

The 9 cases in our study were followed for an average of 198 days. Symptomatic improvement occurred in all eyes. VA recovery occurred in 83% of eyes and depended on presenting foveal involvement. Positive slopes of EZ area over time demonstrated recovery. EZ recovery profiles determined by manual and automated software demonstrated high Pearson correlation coefficients (0.78-0.94). Slab en face EZ analysis demonstrated moderate agreement.

Conclusions:

EZ recovery correlates with symptomatic and VA recovery. Automated EZ analysis shows strong agreement with manually graded EZ analysis in APMPPE. EZ recovery in patients with APMPPE provides a biomarker for recovery and may be applied to other diseases affecting the outer retina.

Using a Macro Lens for Anterior Segment Imaging in Rural Panama

Background: Visual impairment, specifically anterior segment pathology, presents a significant burden of disease in the world. Introduction: Inexpensive tools are necessary to improve eye health of residents in developing countries where care is difficult to access. Our study aimed at determining whether a $5 macro lens attached to a smartphone camera is an effective anterior segment imaging method for screening diseases. Materials and Methods: Fifty four (n = 54) patients had anterior segment imaging performed by using an Easy Macro lens and an iPhone. Imaging was performed at the Floating Doctors' mobile clinic sites in Panama. Images were sent back and graded by two board-certified ophthalmologists using a modified version of the FOTO-ED scale. Statistical analysis was performed by using a Wilcoxon signed-rank test to compare grades between the two imaging modalities. Results: There was no significant difference in overall clinical utility of images obtained by the iPhone versus Easy Macro lens. The iPhone was significantly superior in imaging of the lens and conjunctiva, whereas the Easy Macro lens was superior in regards to the anterior chamber, iris, and lens. Discussion: The imaging modality that best captures pathology is dependent on what part of the anterior segment is being examined. An imaging protocol with a pair of images, one from a smartphone and one from a macro lens, would have significant clinical utility. Conclusion: Our study demonstrates how minimally trained users can deliver effective eye screening via a telemedicine-based approach in a resource-deprived setting. Future directions would be to develop a telemedicine protocol and determine whether it improves clinically measurable outcomes in patients.

Intravitreal Silicone Oil Migration Into the Lateral Cerebral Ventricles

Purpose

Silicone oil (SO) is often used as an intraocular tamponade in repairs of retinal detachments. It may be associated with complications such as cataract, glaucoma, keratopathy, subretinal migration of oil, fibrous epiretinal and sub retinal proliferations, and oil emulsification. The purpose of this report is to describe a rare phenomenon of intraocular silicone oil migration into the cerebral ventricles, which may later be mistaken for intraventricular hemorrhages on neuroimaging.

Methods

Case report with literature review.

Results

A patient with a history of retinal detachment repair with intraocular SO presented with headaches. Neuroimaging revealed SO migration to the cerebral ventricles. The patient was treated conservatively with symptom management and headaches resolved.

Conclusions

We present a case of intraocular SO migration to the cerebral ventricles and review the current literature. We also propose two mechanisms for this phenomenon.

Simultaneously imaging and quantifying in vivo mechanical properties of crystalline lens and cornea using optical coherence elastography with acoustic radiation force excitation

The crystalline lens and cornea comprise the eye's optical system for focusing light in human vision. The changes in biomechanical properties of the lens and cornea are closely associated with common diseases, including presbyopia and cataract. Currently, most in vivo elasticity studies of the anterior eye focus on the measurement of the cornea, while lens measurement remains challenging. To better understand the anterior segment of the eye, we developed an optical coherence elastography system utilizing acoustic radiation force excitation to simultaneously assess the elasticities of the crystalline lens and the cornea in vivo. A swept light source was integrated into the system to provide an enhanced imaging range that covers both the lens and the cornea. Additionally, the oblique imaging approach combined with orthogonal excitation also improved the image quality. The system was tested through first ex vivo and then in vivo experiments using a rabbit model. The elasticities of corneal and lens tissue in an excised normal whole-globe and a cold cataract model were measured to reveal that cataractous lenses have a higher Young's modulus. Simultaneous in vivo elasticity measurements of the lens and cornea were performed in a rabbit model to demonstrate the correlations between elasticity and intraocular pressure and between elasticity and age. To the best of our knowledge, we demonstrated the first in vivo elasticity of imaging of both the lens and cornea using acoustic radiation force-optical coherence elastography, thereby providing a potential powerful clinical tool to advance ophthalmic research in disorders affecting the lens and the cornea.

Animal models of radiation retinopathy - From teletherapy to brachytherapy

Radiation retinopathy is a serious vision-impairing complication of radiation therapy used to treat ocular tumors. Characterized by retinal vasculopathy and subsequent retinal damage, the first sign of radiation retinopathy is the preferential loss of vascular endothelial cells. Ensuing ischemia leads to retinal degradation and late stage neovascularization. Despite the established disease progression, the pathophysiology and cellular mechanisms contributing to radiation retinopathy remain unclear. Clinical experience and basic research for other retinal vasculopathies, such as diabetic retinopathy and retinopathy of prematurity, can inform our understanding of radiation retinopathy; however, the literature investigating the fundamental mechanisms in radiation retinopathy is limited. Treatment trials have shown modest success but, ultimately, fail to address the cellular events that initiate radiation retinopathy. Animal models of radiation retinopathy could provide means to identify effective therapies. Here, we review the literature for all animal models of radiation retinopathy, summarize anatomical highlights pertaining to animal models, identify additional physiological factors to consider when investigating radiation retinopathy, and explore the use of clinically relevant tests for studying in vivo models of radiation retinopathy. We encourage further investigation into the mechanistic characterization of radiation retinopathy in the hope of discovering novel treatments.

Surgical Repair of Traumatic Macular Holes With Extreme Macular Pathology Using an Internal Limiting Membrane Flap Technique

This report describes the use of inverted internal limiting membrane (ILM) flap technique as a treatment option for traumatic macular holes (MHs) with severe macular pathology. An interventional case series of two patients who experienced blunt trauma is reported. One patient developed two adjacent MHs and the second patient a MH with focal tissue avulsion in the fovea. Each patient underwent pars plana vitrectomy with ILM flap creation and intraocular gas tamponade. The ILM flap technique was successfully used for closure of MHs in one patient with a traumatic double MH and another patient with MH with foveal tissue avulsion. Visual acuity and symptoms improved in both patients. The ILM flap technique is a useful option for patients even with advanced pathologic findings subsequent to traumatic MH formation. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:e143-e146.].

Structural and Functional Characterization of Human Stem-Cell-Derived Retinal Organoids by Live Imaging

Purpose

Human pluripotent stem cell (hPSC)-derived retinal organoids are a platform for investigating retinal development, pathophysiology, and cellular therapies. In contrast to histologic analysis in which multiple specimens fixed at different times are used to reconstruct developmental processes, repeated analysis of the same living organoids provides a more direct means to characterize changes. New live imaging modalities can provide insights into retinal organoid structure and metabolic function during in vitro growth. This study employed live tissue imaging to characterize retinal organoid development, including metabolic changes accompanying photoreceptor differentiation.

Methods

Live hPSC-derived retinal organoids at different developmental stages were examined for microanatomic organization and metabolic function by phase contrast microscopy, optical coherence tomography (OCT), fluorescence lifetime imaging microscopy (FLIM), and hyperspectral imaging (HSpec). Features were compared to those revealed by histologic staining, immunostaining, and microcomputed tomography (micro-CT) of fixed organoid tissue.

Results

We used FLIM and HSpec to detect changes in metabolic activity as organoids differentiated into organized lamellae. FLIM detected increased glycolytic activity and HSpec detected retinol and retinoic acid accumulation in the organoid outer layer, coinciding with photoreceptor genesis. OCT enabled imaging of lamellae formed during organoid maturation. Micro-CT revealed three-dimensional structure, but failed to detect lamellae.

Conclusions

Live imaging modalities facilitate real-time and nondestructive imaging of retinal organoids as they organize into lamellar structures. FLIM and HSpec enable rapid detection of lamellar structure and photoreceptor metabolism. Live imaging techniques may aid in the continuous evaluation of retinal organoid development in diverse experimental and cell therapy settings.

Juvenile X-linked retinoschisis responsive to intravitreal corticosteroids

Purpose

To report the case of an adult male with X-linked retinoschisis (XLRS) who presented with cystoid macular edema (CME) that responded consistently to treatment with intravitreal steroids.

Observations

A 39 year old male with unilateral presentation of CME after repair of a retinal detachment secondary to XLRS responded initially to an injection of intravitreal triamcinolone acetonide (IVTA). Central subfield thickness on OCT was reduced. Three months later, the CME recurred and he was unresponsive to topical treatment so repeat IVTA was given, and the CME once again was reduced dramatically. After the next recurrence, intravitreal dexamethasone implant treatment was initiated and successful at treating recurrences in 3 month intervals for 5 additional injections. Finally, an intravitreal fluocinolone acetonide implant was surgically placed with control of CME.

Conclusions and importance

Corticosteroids have never been reported to be effective in CME related to XLRS. Here, we document a case of a man who successfully had decrease of intraretinal fluid and schisis with treatment of intravitreal corticosteroids as demonstrated by spectral domain optical coherence tomography.

Outcomes of medium choroidal melanomas treated with ruthenium brachytherapy guided by three-dimensional pretreatment modeling

PURPOSE

The Collaborative Ocular Melanoma Study (COMS) established iodine-125 (I-125) plaque brachytherapy for eye preserving treatment of medium-sized choroidal melanomas in the United States. Eye Physics I-125 plaque treatment modeled with Plaque Simulator (PS) software yields similar results to COMS. Herein, we report results from a series of 15 patients treated with ruthenium-106 (Ru-106) plaque brachytherapy using PS pretreatment modeling for plaque localization and dosimetry.

METHODS AND MATERIALS

Fifteen patients with medium-sized choroidal melanomas (2.84-5.5 mm in apical height and a basal diameter of 7.8-12.6 mm) treated with ruthenium brachytherapy from 2003 to 2005 were evaluated retrospectively. Baseline and followup data were evaluated for tumor height, best corrected visual acuity, radiation retinopathy, radiation optic neuropathy, postradiation cataract formation, diplopia, and ptosis. Tumor response for both Ru-106 and I-125 plaques planned using the same PS pretreatment modeling was evaluated and compared.

RESULTS

Isotope-specific radiation profiles were compared, and rates of local treatment failure (0%), optic neuropathy (6.7%), retinopathy (20%), and cataracts (33%) were evaluated. Five year-treated tumor heights were approximately 0.61 ± 0.29 (I-125, n = 16) and 0.53 ± 0.17 (Ru-106, n = 6) of their heights at diagnosis.

CONCLUSIONS

This patient subset had background characteristics very similar to those of the COMS and patients treated at our institution with I-125 plaques. Treatment response was equivalent although radiation complications occurred slightly less frequently in the Ru-106 group compared with those treated with I-125. Image-guided three-dimensional pretreatment modeling for plaque localization and dosimetry seems to work equally as well for Ru as for I-125 plaques and justifies more extensive investigation.

A lab-on-a-chip for rapid blood separation and quantification of hematocrit and serum analytes

In this work, a new lab-on-a-chip for rapid analysis of low volume blood samples was designed, fabricated and demonstrated for integration of serum separation, hematocrit evaluation, and protein quantitation. Blood separation was achieved using microchannel flow-based separation. A novel method for evaluating hematocrit from microfluidic flow-separated blood samples was developed using gray scale analysis of a point-and-shoot digital photograph of separated blood in a micochannel. Protein quantitation was subsequently performed in a high surface area-to-volume ratio microfluidic chemiluminescent immunoassay using cell depleted serum produced by microfluidic flow-based separation of whole blood samples. All three steps were achieved in a single microchannel with separation of blood samples and hematocrit evaluation in less than 1 min, and protein quantitation in 5 min.

Cancer screening by systemic administration of a gene delivery vector encoding tumor-selective secretable biomarker expression

Cancer biomarkers facilitate screening and early detection but are known for only a few cancer types. We demonstrated the principle of inducing tumors to secrete a serum biomarker using a systemically administered gene delivery vector that targets tumors for selective expression of an engineered cassette. We exploited tumor-selective replication of a conditionally replicative Herpes simplex virus (HSV) combined with a replication-dependent late viral promoter to achieve tumor-selective biomarker expression as an example gene delivery vector. Virus replication, cytotoxicity and biomarker production were low in quiescent normal human foreskin keratinocytes and high in cancer cells in vitro. Following intravenous injection of virus >90% of tumor-bearing mice exhibited higher levels of biomarker than non-tumor-bearing mice and upon necropsy, we detected virus exclusively in tumors. Our strategy of forcing tumors to secrete a serum biomarker could be useful for cancer screening in high-risk patients, and possibly for monitoring response to therapy. In addition, because oncolytic vectors for tumor specific gene delivery are cytotoxic, they may supplement our screening strategy as a "theragnostic" agent. The cancer screening approach presented in this work introduces a paradigm shift in the utility of gene delivery which we foresee being improved by alternative vectors targeting gene delivery and expression to tumors. Refining this approach will usher a new era for clinical cancer screening that may be implemented in the developed and undeveloped world.

A rapid prototyping method for polymer microfluidics with fixed aspect ratio and 3D tapered channels

In this work, a new method of rapidly fabricating thermopolymer and elastomer microfluidic channels has been developed and characterized for production of microfluidics with fixed aspect ratio and 3D tapered channels. A unique way to attain a desired channel depth by simply altering channel width is demonstrated. This rapid prototyping method is compatible with replication methods such as injection molding, hot embossing and elastomer casting and offers the ability to fabricate multiple channel depths (5 microm-1 mm) simultaneously in a single lithographic step. This method yields facile fabrication of 3-dimensionally tapered channels and polymer lab chips.

Beri-beri: age-gender bias in The Gambia

This paper investigates a suspected outbreak of beri-beri which occurred in The Gambia in 1988. The outbreak was spatially specific and had a distinct age and gender bias, with young men aged 15-49 being the group mainly affected. The age and gender bias of the outbreak is particularly interesting as women and children in the developing world are usually more susceptable to conditions associated with malnourishment, than men. The authors investigate the peculiar nature of the outbreak and find that they cannot easily explain the apparent age and gender bias. The authors note that at the time of the outbreak medical treatment took precedence over socio-economic investigations. This makes it difficult to ascertain why certain age and gender groups were affected and thus to target them for future preventative health education programmes. This case study therefore concludes, that where possible, medical investigations must be combined with socio-economic studies if future outbreaks of this kind are to be avoided.