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Purpose.: To quantitatively investigate the reflectivity and structure of the outer retinal layers in children with hyperopic anisometropic amblyopia by using swept-source optical coherence tomography (SS-OCT). Methods: Seventy-eight patients with amblyopia and 64 age-matched children with normal vision were included in this study. All participants underwent SS-OCT and detailed ophthalmic examinations. Longitudinal reflectance profile measurements were measured using Image J. The reflectivity of outer retinal layers was measured at the three selected positions: subfovea, 1 mm nasal to the fovea, and 1 mm temporal to the fovea. The reflectivity ratios were calculated by outer retinal layers divided by the nuclear layer (ONL) for normalization. Photoreceptor outer segment layer thickness was also measured. The results were compared between the amblyopia and normal controls. The possible effects of age, sex, and axial length on results were adjusted by generalized estimating equations. Results: Photoreceptor outer segment layer thickness was significantly greater in amblyopic eyes than in normal control eyes at all three regions (18.41 ± 1.83 vs. 16.84 ± 1.39, P < 0.001 at the fovea; 14.78 ± 1.34 vs. 14.19 ± 1.40, P = 0.030 at 1 mm nasal to the foveal; 14.92 ± 1.48 vs. 14.41 ± 1.32, P = 0.049 at 1 mm temporal to the fovea). The reflectivity ratio of outer segment/ONL was higher only at 1 mm nasal to the fovea (2.94 ± 0.61 vs. 2.70 ± 0.42, P = 0.02). Subfoveal OS thickness was positively correlated with choroidal thickness (r = 0.248, P = 0.018) but was not correlated with spherical equivalent, age, axial length, or logMAR visual acuity. Conclusion: Quantitative measurement of SS-OCT images revealed greater photoreceptor outer segments in both eyes of children with amblyopia than in normal control eyes. A thicker OS thickness is somehow related to amblyopia, and this may be a new useful diagnostic parameter for amblyopia. [ABSTRACT FROM AUTHOR]

Photoreceptors (PRs) and retinal pigment epithelial (RPE) cells form a functional unit called the PR-RPE complex. The PR-RPE complex plays a critical role in maintaining retinal homeostasis and function, and the quantification of its structure and topographical arrangement across the macula are important for understanding the etiology, mechanisms, and progression of many retinal diseases. However, the three-dimensional cellular morphology of the PR-RPE complex in living human eyes has not been completely described due to limitations in imaging techniques. We used the cellular resolution and depth-sectioning capabilities of a custom, high-speed Fourier domain mode-locked laser-based adaptive optics–optical coherence tomography (FDML-AO-OCT) platform to characterize human PR-RPE complex topography across the temporal macula from eleven healthy volunteers. With the aid of a deep learning algorithm, key metrics were extracted from the PR-RPE complex of averaged AO-OCT volumes including PR and RPE cell density, PR outer segment length (OSL), and PR/RPE ratio. We found a tight grouping among our cohort for PR density, with a mean (±SD) value of 53,329 (±8106) cells/mm2 at 1° decreasing to 8669 (±737) cells/mm2 at 12°. We observed a power function relationship between eccentricity and both PR density and PR/RPE ratio. We found similar variability in our RPE density measures, with a mean value of 7335 (±681) cells/mm2 at 1° decreasing to 5547 (±356) cells/mm2 at 12°, exhibiting a linear relationship with a negative slope of −123 cells/mm2 per degree. OSL monotonically decreased from 33.3 (±2.4) µm at 1° to 18.0 (±1.8) µm at 12°, following a second-order polynomial relationship. PR/RPE ratio decreased from 7.3 (±0.9) µm at 1° to 1.5 (±0.1) µm at 12°. The normative data from this investigation will help lay a foundation for future studies of retinal pathology. [ABSTRACT FROM AUTHOR]

The functionality of photoreceptors, rods, and cones is highly dependent on their outer segments (POS), a cellular compartment containing highly organized membranous structures that generate biochemical signals from incident light. While POS formation and degeneration are qualitatively assessed on microscopy images, reliable methodology for quantitative analyses is still limited. Here, we developed methods to quantify POS (QuaPOS) maturation and quality on retinal sections using automated image analyses. POS formation was examined during the development and in adulthood of wild-type mice via light microscopy (LM) and transmission electron microscopy (TEM). To quantify the number, size, shape, and fluorescence intensity of POS, retinal cryosections were immunostained for the cone POS marker S-opsin. Fluorescence images were used to train the robust classifier QuaPOS-LM based on supervised machine learning for automated image segmentation. Characteristic features of segmentation results were extracted to quantify the maturation of cone POS. Subsequently, this quantification method was applied to characterize POS degeneration in "cone photoreceptor function loss 1" mice. TEM images were used to establish the ultrastructural quantification method QuaPOS-TEM for the alignment of POS membranes. Images were analyzed using a customwritten MATLAB code to extract the orientation of membranes from the image gradient and their alignment (coherency). This analysis was used to quantify the POS morphology of wild-type and two inherited retinal degeneration ("retinal degeneration 19" and "rhodopsin knock-out") mouse lines. Both automated analysis technologies provided robust characterization and quantification of POS based on LM or TEM images. Automated image segmentation by the classifier QuaPOS-LM and analysis of the orientation of membrane stacks by QuaPOS-TEM using fluorescent or TEM images allowed quantitative evaluation of POS formation and quality. The assessments showed an increase in POS number, volume, and membrane coherency during wild-type postnatal development, while a decrease in all three observables was detected in different retinal degeneration mouse models. All the code used for the presented analysis is open source, including example datasets to reproduce the findings. Hence, the QuaPOS quantification methods are useful for in-depth characterization of POS on retinal sections in developmental studies, for disease modeling, or after therapeutic interventions affecting photoreceptors. [ABSTRACT FROM AUTHOR]

The functionality of photoreceptors, rods, and cones is highly dependent on their outer segments (POS), a cellular compartment containing highly organized membranous structures that generate biochemical signals from incident light. While POS formation and degeneration are qualitatively assessed on microscopy images, reliable methodology for quantitative analyses is still limited. Here, we developed methods to quantify POS (QuaPOS) maturation and quality on retinal sections using automated image analyses. POS formation was examined during the development and in adulthood of wild-type mice via light microscopy (LM) and transmission electron microscopy (TEM). To quantify the number, size, shape, and fluorescence intensity of POS, retinal cryosections were immunostained for the cone POS marker S-opsin. Fluorescence images were used to train the robust classifier QuaPOS-LM based on supervised machine learning for automated image segmentation. Characteristic features of segmentation results were extracted to quantify the maturation of cone POS. Subsequently, this quantification method was applied to characterize POS degeneration in “cone photoreceptor function loss 1” mice. TEM images were used to establish the ultrastructural quantification method QuaPOS-TEM for the alignment of POS membranes. Images were analyzed using a custom-written MATLAB code to extract the orientation of membranes from the image gradient and their alignment (coherency). This analysis was used to quantify the POS morphology of wild-type and two inherited retinal degeneration (“retinal degeneration 19” and “rhodopsin knock-out”) mouse lines. Both automated analysis technologies provided robust characterization and quantification of POS based on LM or TEM images. Automated image segmentation by the classifier QuaPOS-LM and analysis of the orientation of membrane stacks by QuaPOS-TEM using fluorescent or TEM images allowed quantitative evaluation of POS formation and quality. The assessments showed an increase in POS number, volume, and membrane coherency during wild-type postnatal development, while a decrease in all three observables was detected in different retinal degeneration mouse models. All the code used for the presented analysis is open source, including example datasets to reproduce the findings. Hence, the QuaPOS quantification methods are useful for in-depth characterization of POS on retinal sections in developmental studies, for disease modeling, or after therapeutic interventions affecting photoreceptors.

Rod and cone photoreceptor outer segment (OS) structural integrity is essential for normal vision; disruptions contribute to a broad variety of retinal ciliopathies. OSs possess many hundreds of stacked membranous disks, which capture photons and scaffold the phototransduction cascade. Although the molecular basis of OS structure remains unresolved, recent studies suggest that the photoreceptor-specific tetraspanin, peripherin-2/rds (P/rds), may contribute to the highly curved rim domains at disk edges. Here, we demonstrate that tetrameric P/rds self-assembly is required for generating high-curvature membranes in cellulo, implicating the noncovalent tetramer as a minimal unit of function. P/rds activity was promoted by disulfide-mediated tetramer polymerization, which transformed localized regions of curvature into high-curvature tubules of extended lengths. Transmission electron microscopy visualization of P/rds purified from OS membranes revealed disulfide-linked tetramer chains up to 100 nm long, suggesting that chains maintain membrane curvature continuity over extended distances. We tested this idea in Xenopus laevis photoreceptors, and found that transgenic expression of nonchain-forming P/rds generated abundant high-curvature OS membranes, which were improperly but specifically organized as ectopic incisures and disk rims. These striking phenotypes demonstrate the importance of P/rds tetramer chain formation for the continuity of rim formation during disk morphogenesis. Overall, this study advances understanding of the normal structure and function of P/rds for OS architecture and biogenesis, and clarifies how pathogenic loss-of-function mutations in P/rds cause photoreceptor structural defects to trigger progressive retinal degenerations. It also introduces the possibility that other tetraspanins may generate or sense membrane curvature in support of diverse biological functions.

Background: The photoreceptor outer segment (PROS) layer demonstrates focal thinning above the fluorescein leakage in acute central serous chorioretinopathy (CSC); however, the nature of this phenomenon is not known. Objectives: To study the relationship between the PROS layer and thickness of the outer retinal layers above the fluorescein leakage in newly diagnosed acute CSC. Design: Single-center retrospective study. Methods: All participants received multimodal imaging, including fluorescein angiography and optical coherence tomography. Thickness of PROS, outer nuclear layer (ONL), and ONL-outer plexiform layer (OPL) complex was measured above the leakage and outside the leakage within the area of neurosensory detachment. The number of intraretinal hyperreflective foci of the outer retina was counted. The correlation between PROS thickness and ONL, OPL-ONL complex thickness, and the number of intraretinal hyperreflective foci was calculated. Results: Fifty eyes of 48 patients (38 males and 10 females, 43.8 ± 10.6 years) with a mean symptom duration of 1.4 ± 1.3 months were included. PROS thickness above the fluorescein leakage showed a statistically significant correlation with ONL thickness, OPL-ONL complex thickness, and the number of hyperreflective foci in the outer retina, 0.57, 0.60, and −0.46, respectively (p < 0.001). Measuring the extent of PROS thinning above the leakage in newly diagnosed CSC allowed to predict self-resolution of subretinal fluid. The greatest linear dimension of PROS thinning showed an area under the receiver operating curve (ROC) curve of 0.98. The cases without PROS thinning had the fastest resolution of subretinal fluid. Conclusion: PROS thinning above the fluorescein leakage in acute CSC is associated with thinning of the outer retinal layers and reveals mild outer retinal atrophy. The absence of PROS thinning predicts faster resolution of CSC. [ABSTRACT FROM AUTHOR]

• Repetitive low-level red-light therapy is a newly discovered effective method of myopia prevention and control. • Red light therapy is safe within 12 months and can enhance multifocal electroretinography responses. • Red light therapy increases the relative reflectance of photoreceptor outer segments which may reflect potentially detrimental effects. To investigate the safety of repetitive low-level red-light therapy (RLRLT) in children with myopia. Children with myopia were assigned to the RLRL and control groups. Axial length (AL) and spherical equivalent refraction (SER) were followed up at 3-, 6-, and 12-month. To evaluate the safety of RLRLT, at 6 and 12 months in the RLRL group, multifocal electroretinography (mfERG) and contrast sensitivity were recorded. Furthermore, optical coherence tomography was used to measure the relative reflectance of the ellipsoid zone (rEZR), photoreceptor outer segment (rPOSR), and retinal pigment epithelium (rRPER). A total of 108 children completed the trial (55 in the RLRL group and 53 in the control group). After 3, 6, and 12 months, AL was shorter and SER less myopic in the RLRL group than in the control group. Regarding the safety of the RLRLT, the response density and amplitude of the P1 wave of the first ring of the mfERG increased significantly at 6 months (P = 0.001 and P = 0.017, respectively). At 6 and 12 months, contrast sensitivity at the high spatial frequency increased. Moreover, the rEZR increased significantly at 6 months (P = 0.029), the rPOSR increased significantly at 6 and 12 months (both P < 0.001), and the increase in rPOSR was greater with greater AL regression. Based on retinal function and structure follow-up, RLRLT was safe within 12 months. However, rEZR and rPOSR increased, the effects of this phenomenon requires further observation. [ABSTRACT FROM AUTHOR]

Retinal photoreceptors undergo daily renewal of their distal outer segments, a process indispensable for maintaining retinal health. Photoreceptor outer segment (POS) phagocytosis occurs as a daily peak, roughly about 1 hour after light onset. However, the underlying cellular and molecular mechanisms which initiate this process are still unknown. Here we show that, under constant darkness, mice deficient for core circadian clock genes (Per1 and Per2) lack a daily peak in POS phagocytosis. By qPCR analysis, we found that core clock genes were rhythmic over 24 hours in both WT and Per1, Per2 double mutant whole retinas. More precise transcriptomics analysis of laser capture microdissected WT photoreceptors revealed no differentially expressed genes between time points preceding and during the peak of POS phagocytosis. In contrast, we found that microdissected WT retinal pigment epithelium (RPE) had a number of genes that were differentially expressed at the peak phagocytic time point compared to adjacent ones. We also found a number of differentially expressed genes in Per1, Per2 double mutant RPE compared to WT ones at the peak phagocytic time point. Finally, based on STRING analysis, we found a group of interacting genes that potentially drive POS phagocytosis in the RPE. This potential pathway consists of genes such as: Pacsin1, Syp, Camk2b, and Camk2d among others. Our findings indicate that Per1 and Per2 are necessary clock components for driving POS phagocytosis and suggest that this process is transcriptionally driven by the RPE. [ABSTRACT FROM AUTHOR]

Copyright of Der Ophthalmologe is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose: To quantitatively investigate the reflectivity and structure of the outer retinal layers on spectral-domain optical coherence tomography (SD-OCT) in commotio retinae. Methods: Nineteen patients with acute macular commotio retinae and 19 age-matched normal controls were examined using SD-OCT. Longitudinal reflectance profiles (LRP) were obtained using Image J. The reflectivity of outer retinal layers was measured at the fovea, 1 mm nasal to fovea and 1 mm temporal to fovea. The reflectivity ratios of outer retinal layers divided by the outer nuclear layer (ONL) were calculated for normalization. Photoreceptor outer segment layer thickness was also measured. The results were compared between the patients and controls. Results: The reflectivity ratio of ellipsoid zone/ONL and outer segment/ONL was higher in commotio retinae than in controls only at fovea (12.66 ± 4.73 vs 9.67 ± 3.34, p = 0.041; 7.70 ± 2.20 vs 3.73 ± 1.63, p < 0.001, respectively) but not at 1 mm nasal or temporal to the fovea. Photoreceptor outer segment layer thickness was significantly shorter in commotio retinae compared to controls at all three locations (19.64 ± 3.05 vs 25.16 ± 3.53, 16.95 ± 4.02 vs 20.00 ± 3.00, and 15.42 ± 3.22 vs 20.05 ± 2.48, respectively, all p < 0.05). Conclusions: Quantitative measurement of SD-OCT images revealed that shortening of photoreceptor outer segment is an additional, and potentially better, biomarker for commotio retinae on top of increased reflectivity. [ABSTRACT FROM AUTHOR]

Purpose: Retinal degeneration in birdshot chorioretinopathy can be quantified using spectral domain optical coherence tomography by measuring the photoreceptor outer segment (PROS) volume. The purpose of this study was to determine if the PROS volume in BSCR responds to systemic immunomodulatory therapy (IMT). Methods: Retrospective chart review with analysis of PROS volume derived from spectral domain optical coherence tomography. Results: We identified a total of three patients who met our inclusion criteria. At baseline, all patients had abnormal PROS and/or ellipsoid layer findings on spectral domain optical coherence tomography. After systemic immunomodulatory therapy, these abnormalities improved, and PROS volume increased, in all patients (P, 0.05). Conclusion: PROS volume can increase after systemic treatment of birdshot chorioretinopathy. This SD-OCT parameter may serve as a useful marker of retinal degeneration in BSCR, and may be a useful outcome measure in monitoring treatment response in birdshot chorioretinopathy. [ABSTRACT FROM AUTHOR]

Copyright of Der Ophthalmologe is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Photoreceptor disease results in irreparable vision loss and blindness, which has a dramatic impact on quality of life. Pathogenic mutations in RP1L1 lead to photoreceptor degenerations such as occult macular dystrophy and retinitis pigmentosa. RP1L1 is a component of the photoreceptor axoneme, the backbone structure of the photoreceptor’s light-sensing outer segment. We generated an rp1l1 zebrafish mutant using CRISPR/Cas9 genome editing. Mutant animals had progressive photoreceptor functional defects as determined by electrophysiological assessment. Optical coherence tomography showed gaps in the photoreceptor layer, disrupted photoreceptor mosaics, and thinner retinas. Mutant retinas had disorganized photoreceptor outer segments and lipid-rich subretinal drusenoid deposits between the photoreceptors and retinal pigment epithelium. Our mutant is a novel model of RP1L1-associated photoreceptor disease and the first zebrafish model of photoreceptor degeneration with reported subretinal drusenoid deposits, a feature of age-related macular degeneration.

Purpose: To describe a case of macular microcysts associated with advanced secondary glaucoma from Schwartz--Matsuo syndrome. Methods: Clinical presentation, color fundus photography, optic disk photography, visual fields, and optical coherence tomography are presented. Results: A 32-year-old woman presented with advanced, unilateral secondary glaucoma associated with a macula-on rhegmatogenous retinal detachment. She was diagnosed with Schwartz--Matsuo syndrome. Spectral domain optical coherence tomography showed macular microcystic changes in the paracentral retina at the level of the inner nuclear layer. Conclusion: Macular microcystic changes in the paracentral inner nuclear layer on spectral domain optical coherence tomography have been described in eyes with optic atrophy associated with a variety of diseases. This is the first described case of macular microcysts associated with advanced secondary glaucoma from Schwartz--Matsuo syndrome and may offer insights into the pathogenesis of these microcysts. [ABSTRACT FROM AUTHOR]