Visual Cortical Thickness Increases with Prolonged Artificial Vision Restoration.

The Argus II retinal prosthesis restores visual perception to late blind patients. It has been shown that structural changes occur in the brain due to late-onset blindness, including cortical thinning in visual regions of the brain. Following vision restoration, it is not yet known whether these visual regions are reinvigorated and regain a normal cortical thickness or retain the diminished thickness from blindness. We evaluated the cortical thicknesses of ten Argus II Retinal Prostheses patients, ten blind patients, and thirteen sighted participants. The Argus II patients on average had a thicker left Cuneus Cortex and Lateral Occipital Cortex relative to the blind patients. The duration of the Argus II use (time since implant in active users) significantly partially correlated with thicker visual cortical regions in the left hemisphere. Furthermore, in the two case studies (scanned before and after implantation), the patient with longer device use (44.5 months) had an increase in the cortical thickness of visual regions, whereas the shorter-using patient did not (6.5 months). Finally, a third case, scanned at three time points post-implantation, showed an increase in cortical thickness in the Lateral Occipital Cortex between 43.5 and 57 months, which was maintained even after 3 years of disuse (106 months). Overall, the Argus II patients' cortical thickness was on average significantly rejuvenated in two higher visual regions and, patients using the implant for a longer duration had thicker visual regions. This research raises the possibility of structural plasticity reversing visual cortical atrophy in late-blind patients with prolonged vision restoration.

Comparison of The Results of Sponsored Genetic Testing Panels for Inherited Retinal Diseases.

Background/Objectives: Gene therapy's emergence has made molecular diagnosis for inherited retinal diseases clinically significant. Free genetic testing panels have improved testing access in clinical practice, yet the interpretation of results, especially variants of unknown significance (VUS), remains challenging and requires expertise. This study shares our experience in utilizing sponsored IRD panel tests by Invitae and Blueprint Genetics (BG), reporting their positivity rates, and comparing their reclassification of variants through amendments. Methods: This retrospective study analyzed genetic test reports from patients who underwent testing via Invitae or BG panels. A positive test was determined if there was a pathogenic mutation in an autosomal dominant gene, two pathogenic mutations in an autosomal recessive gene, or a pathogenic mutation in an X-linked gene in a male patient. Results: The testing positivity rates were 34.9% for Invitae (n = 109) and 42.1% for BG (n = 107). Invitae had more pathogenic variants per report (0.87 vs. 0.58 variants, p = 0.0038) and issued more amendments than BG (0.54 vs. 0.03 amendments; p < 0.01). Of the Invitae variant classification changes, 66.2% switched a VUS to benign. In the BG group, 75% of variant reclassifications changed a VUS to pathogenic. As a result of the Invitae amendments, 88% did not change the overall report result. Conclusions: While free-of-charge genetic testing panels offer valuable insights for diagnosing IRD, limitations such as low diagnostic yield and variant classification discrepancies persist between Invitae and BG. VUS should not be considered pathogenic in the clinical decision-making process. Careful interpretation of genetic testing is required.

Mycobacterium dormancy and antibiotic tolerance within the retinal pigment epithelium of ocular tuberculosis.

Tuberculosis (TB) is a leading cause of death among infectious diseases worldwide due to latent TB infection, which is the critical step for the successful pathogenic cycle. In this stage, Mycobacterium tuberculosis resides inside the host in a dormant and antibiotic-tolerant state. Latent TB infection can also lead to multisystemic diseases because M. tuberculosis invades virtually all organs, including ocular tissues. Ocular tuberculosis (OTB) occurs when the dormant bacilli within the ocular tissues reactivate, originally seeded by hematogenous spread from pulmonary TB. Histological evidence suggests that retinal pigment epithelium (RPE) cells play a central role in immune privilege and in protection from antibiotic effects, making them an anatomical niche for invading M. tuberculosis. RPE cells exhibit high tolerance to environmental redox stresses, allowing phagocytosed M. tuberculosis bacilli to maintain viability in a dormant state. However, the microbiological and metabolic mechanisms determining the interaction between the RPE intracellular environment and phagocytosed M. tuberculosis are largely unknown. Here, liquid chromatography-mass spectrometry metabolomics were used to illuminate the metabolic state within RPE cells reprogrammed to harbor dormant M. tuberculosis bacilli and enhance antibiotic tolerance. Timely and accurate diagnosis as well as efficient chemotherapies are crucial in preventing the poor visual outcomes of OTB patients. Unfortunately, the efficacy of current methods is highly limited. Thus, the results will lead to propose a novel therapeutic option to synthetically kill the dormant M. tuberculosis inside the RPE cells by modulating the phenotypic state of M. tuberculosis and laying the foundation for a new, innovative regimen for treating OTB. IMPORTANCE: Understanding the metabolic environment within the retinal pigment epithelium (RPE) cells altered by infection with Mycobacterium tuberculosis and mycobacterial dormancy is crucial to identify new therapeutic methods to cure ocular tuberculosis. The present study showed that RPE cellular metabolism is altered to foster intracellular M. tuberculosis to enter into the dormant and drug-tolerant state, thereby blunting the efficacy of anti-tuberculosis chemotherapy. RPE cells serve as an anatomical niche as the cells protect invading bacilli from antibiotic treatment. LC-MS metabolomics of RPE cells after co-treatment with H2O2 and M. tuberculosis infection showed that the intracellular environment within RPE cells is enriched with a greater level of oxidative stress. The antibiotic tolerance of intracellular M. tuberculosis within RPE cells can be restored by a metabolic manipulation strategy such as co-treatment of antibiotic with the most downstream glycolysis metabolite, phosphoenolpyruvate.

Mycobacterium dormancy and antibiotic tolerance within the retinal pigment epithelium of ocular tuberculosis.

Tuberculosis (TB) is a leading cause of death among infectious diseases worldwide due to latent TB infection, which is the critical step for the successful pathogenic cycle. In this stage, Mycobacterium tuberculosis resides inside the host in a dormant and antibiotic-tolerant state. Latent TB infection can lead to a multisystemic diseases because M. tuberculosis invades virtually all organs, including ocular tissues. Ocular tuberculosis (OTB) occurs when the dormant bacilli within ocular tissues reactivate, originally seeded by hematogenous spread from pulmonary TB. Timely and accurate diagnosis as well as efficient chemotherapies are crucial in preventing poor visual outcomes of OTB patients. Histological evidence suggests that retinal pigment epithelium (RPE) cells play a central role in immune privilege and in the protection from the antibiotic effects, making them an anatomical niche for invading M. tuberculosis . RPE cells exhibit high tolerance to environmental redox stresses, allowing phagocytosed M. tuberculosis bacilli to maintain viability in a dormant state. However, the microbiological and metabolic mechanisms determining the interaction between the RPE intracellular environment and phagocytosed M. tuberculosis are largely unknown. Here, liquid chromatography mass spectrometry (LC-MS) metabolomics was used to illuminate the metabolic state within RPE cells reprogrammed to harbor dormant M. tuberculosis bacilli and enhance the antibiotic tolerance. The results have led to propose a novel therapeutic option to synthetically kill the dormant M. tuberculosis inside the RPE cells by modulating the phenotypic state of M. tuberculosis , thus laying the foundation for a new, innovative regimen for treating OTB. Importance: Understanding the metabolic environment within the retinal pigment epithelium (RPE) cells altered by infection with M. tuberculosis and mycobacterial dormancy is crucial to identify new therapeutic methods to cure OTB. The present study showed that RPE cellular metabolism is altered to foster intracellular M. tuberculosis to enter into the dormant and drug tolerant state, thereby blunting the efficacy of anti-TB chemotherapy. RPE cells serve as an anatomical niche as the cells protect invading bacilli from antibiotic treatment. LC-MS metabolomics of RPE cells after co-treatment with H2O2 and M. tuberculosis infection showed that intracellular environment within RPE cells is enriched with greater level of oxidative stress. The antibiotic tolerance of intracellular M. tuberculosis within RPE cells can be restored by a metabolic manipulation strategy such as co-treatment of antibiotic with the most downstream glycolysis metabolite, phosphoenolpyruvate.

Retinal Cell Biology in Health and Disease.

The intricate network of cells and processes that govern retinal health has long been a subject of fascination and intensive study within the scientific community [...].

Comparison of Retinal Metabolic Activity and Structural Development between rd10 Mice and Normal Mice Using Multiphoton Fluorescence Lifetime Imaging Microscopy.

Fluorescence lifetime imaging microscopy (FLIM) is a technique that analyzes the metabolic state of tissues based on the spatial distribution of fluorescence lifetimes of certain interacting molecules. We used multiphoton FLIM to study the metabolic state of developing C57BL6/J and rd10 retinas based on the fluorescence lifetimes of free versus bound nicotinamide adenine dinucleotide and nicotinamide adenine dinucleotide phosphate (NAD(P)H), with free NAD(P)H percentages suggesting increased glycolysis and bound NAD(P)H percentages indicating oxidative phosphorylation. The mice were sacrificed and enucleated at various time points throughout their first 3 months of life. The isolated eyecups were fixed, sectioned using a polyacrylamide gel embedding technique, and then analyzed with FLIM. The results suggested that in both C57BL6/J mice and rd10 mice, oxidative phosphorylation initially decreased and then increased, plateauing over time. This trend, however, was accelerated in rd10 mice, with its turning point occurring at p10 versus the p30 turning point in C57BL6/J mice. There was also a noticeable difference in oxidative phosphorylation rates between the outer and inner retinas in both strains, with greater oxidative phosphorylation present in the latter. A greater understanding of rd10 and WT metabolic changes during retinal development may provide deeper insights into retinal degeneration and facilitate the development of future treatments.

Frequency and Pattern of Worldwide Ocular Gene Therapy Clinical Trials up to 2022.

The purpose of this study is to describe worldwide gene therapy clinical trials aimed at treating ophthalmic disorders. Information regarding all worldwide clinical trials was collected through 15 different sources, including ClinicalTrials.gov. There were 159 gene therapy clinical trials on ophthalmic diseases up until 2022. Phase 1/2 trials had the highest frequency (50-32%), followed by phase 2 (33-21%); 107 trials (67%) were conducted in a single country, and 50 trials (31%) were multinational. Overall, the USA was the site of 113 (71%) single or multinational trials. Of the trials, 153 (96%) targeted retina and optic nerve disorders, 3 (2%) glaucoma, 2 (1%) uveitis, and 1 (1%) cornea; 104 trials (65%) employed gene augmentation using viral vectors, and the remaining employed other methods such as inhibitory RNA (18-11%) and cell-based gene therapy using encapsulated cell technology (18-11%). For gene augmentation trials, adeno-associated virus was used for transgene delivery in 87% of cases. The most common conditions targeted by gene augmentation included inherited retinal (74%) and age-related macular degeneration (wet, 14%; dry, 7%). Overall, a large number of gene therapy clinical trials have been conducted in the eye, and so far, one has led to regulatory approval.

Effects of Smoothing and Adaptive Filtering in Multifocal Electroretinography (mfERG).

(1) Background: mfERG testing is used to study the function of cone photoreceptors in the central retina. Various filters including "smoothing" (Smooth) and "adaptive data filtering" (Adapt) are used to simplify raw data. This study will seek to characterize the effect of data modification on raw patient data. (2) Methods: This was a retrospective study of patients with mfERG results at our institution. For each patient, raw mfERG data without filtering, with smooth level 4 modifier applied, and with adapt level 4 applied were collected and compared. (4) Conclusions: In all patients, smoothing and adaptive filter modifiers create statistically significant differences in both P1 latency and P1 amplitude values when compared to raw data. The impacts of these filters demonstrated in this study should impact physicians' decision making when interpreting mfERG results.

Optical coherence tomography in healthy human subjects in the setting of prolonged dark adaptation.

Human studies have established that short periods of dark adaptation can induce outer retinal thinning and various band intensity changes that can be detected with Optical Coherence Tomography (OCT). Similar findings were observed in mice, including a positive correlation between the degree of outer retinal changes and dark adaptation duration. We decided to assess potential retinal structural changes following prolonged dark adaptation in humans. 40 healthy subjects without any ocular diseases participated in this study. For each subject, one eye was covered for dark adaptation for four hours, and the other eye was left uncovered as a control. Before and after the dark adaptation period, both eyes were assessed with OCT. Using the Heidelberg Spectralis system, basic statistical functions, and qualitative and quantitative analysis, we were able to compare retinal layer thicknesses and band intensities between covered (dark adapted) versus uncovered (control) eyes. Prolonged dark adaptation did not induce any significant thickness, volume, or intensity changes in the outer retina or in the inner or overall retina. These observations thus alter our current understanding of the mechanisms underlying dark adaptation's neuroprotective effects in preventing blindness and require further study.

Sight restoration reverses blindness-induced cross-modal functional connectivity changes between the visual and somatosensory cortex at rest.

Resting-state functional connectivity (rsFC) has been used to assess the effect of vision loss on brain plasticity. With the emergence of vision restoration therapies, rsFC analysis provides a means to assess the functional changes following sight restoration. Our study demonstrates a partial reversal of blindness-induced rsFC changes in Argus II retinal prosthesis patients compared to those with severe retinitis pigmentosa (RP). For 10 healthy control (HC), 10 RP, and 7 Argus II subjects, four runs of resting-state functional magnetic resonance imaging (fMRI) per subject were included in our study. rsFC maps were created with the primary visual cortex (V1) as the seed. The rsFC group contrast maps for RP > HC, Argus II > RP, and Argus II > HC revealed regions in the post-central gyrus (PostCG) with significant reduction, significant enhancement, and no significant changes in rsFC to V1 for the three contrasts, respectively. These findings were also confirmed by the respective V1-PostCG ROI-ROI analyses between test groups. Finally, the extent of significant rsFC to V1 in the PostCG region was 5,961 in HC, 0 in RP, and 842 mm3 in Argus II groups. Our results showed a reduction of visual-somatosensory rsFC following blindness, consistent with previous findings. This connectivity was enhanced following sight recovery with Argus II, representing a reversal of changes in cross-modal functional plasticity as manifested during rest, despite the rudimentary vision obtained by Argus II patients. Future investigation with a larger number of test subjects into this rare condition can further unveil the profound ability of our brain to reorganize in response to vision restoration.

Insights into Metabolic Activity and Structure of the Retina through Multiphoton Fluorescence Lifetime Imaging Microscopy in Mice.

Fluorescence lifetime imaging microscopy (FLIM) evaluates the metabolic state of tissue based on reduced nicotinamide adenine dinucleotide (NAD(P)H) and flavin adenine dinucleotide (FAD). Fluorescence lifetime imaging ophthalmoscopy (FLIO) can image the fundus of the eyes, but cannot detect NAD(P)H. We used multiphoton FLIM to study the metabolic state of the retina in fixed eyes of wild-type mice C57BL6/J. We sectioned the eye using a polyacrylamide gel-embedding technique and estimated the percentage of bound NAD(P)H. We found that oxidative phosphorylation was the predominant metabolic state, particularly in the inner retina, when a fixed retina was used. We also demonstrated the feasibility of FAD imaging of the retina. In addition, we demonstrated that autofluorescence and various FLIM channels, such as hemoglobin, melanin and collagen, can be used to evaluate the structure of the retina and other parts of the eye without any special staining.

Capillary density and caliber as assessed by optical coherence tomography angiography may be significant predictors of diabetic retinopathy severity.

PURPOSE: To validate retinal capillary density and caliber associations with diabetic retinopathy (DR) severity in different clinical settings. METHODS: This cross-sectional study assessed retinal capillary density and caliber in the superficial retinal layer of 3-mm OCTA scans centered on the fovea. Images were collected from non-diabetic controls and subjects with mild or referable DR (defined DR worse than mild DR) between February 2016 and December 2019 at secondary and tertiary eye care centers. Vessel Skeleton Density (VSD), a measure of capillary density, and Vessel Diameter Index (VDI), a measure of vascular caliber, were calculated from these images. Discriminatory performance of VSD and VDI was evaluated using multivariable logistic regression models predicting DR severity with adjustments for sex, hypertension, and hyperlipidemia. Area under the curve (AUC) was estimated. Model performance was evaluated in two different cohorts. RESULTS: This study included 594 eyes from 385 subjects. Cohort 1 was a training cohort of 509 eyes including 159 control, 155 mild non-proliferative DR (NPDR) and 195 referable DR eyes. Cohort 2 was a validation cohort consisting of 85 eyes including 16 mild NPDR and 69 referable DR eyes. In Cohort 1, addition of VSD and VDI to a model using only demographic data significantly improved the model's AUC for discrimination of eyes with any DR severity from controls (0.91 [95% CI, 0.88-0.93] versus 0.80 [95% CI, 0.76-0.83], p < 0.001) and eyes with referable DR from mild NPDR (0.90 [95% CI, 0.86-0.93] versus 0.69 [95% CI, 0.64-0.75], p < 0.001). The transportability of this regression model was excellent when implemented in Cohort 2 for the referable DR versus mild NPDR comparison. The odds ratio of having any DR compared to control subjects, and referable DR compared to mild DR decreased by 15% (95% CI: 12-18%), and 13% (95% CI: 10-15%), respectively, for every 0.001 unit increase in VSD after adjusting for comorbidities. CONCLUSION: OCTA-derived capillary density has real world clinical value for rapidly assessing DR severity.

Ischemic index and distribution of retinal capillary non-perfusion in neovascular glaucoma.

INTRODUCTION: Neovascular Glaucoma (NVG) is a condition normally caused by hypoxic posterior ocular disease, which produces angiogenic factors such as vascular endothelial growth factor (VEGF) that stimulate new vessel proliferation of the anterior segment and angle, eventually leading to angle closure, reduced outflow of aqueous humor and increased intraocular pressure. Without treatment elevated intraocular pressure can rapidly progress to loss of vision. Treatment includes addressing the intraocular pressure and reducing the ischemic drive with panretinal photocoagulation (PRP) of the ischemic retina. Recent imaging advancements allow for ultra-widefield fluorescein angiography (UWFA) which expand the amount of peripheral retina that can be evaluated for non-perfusion. Here we aim to study patterns of non-perfusion in NVG using a group of PRP naïve patients with recent onset NVG. METHODS: This study is a retrospective single-center cross-sectional study of patients seen at LAC + USC Medical Center from January 2015 to April 2020 with new onset NVG, without PRP and with UWFA completed. The percentage of ischemic index of the retina was calculated from the UWFA and evaluated in three distinct zones centered on the fovea: the posterior pole, the mid periphery, and far periphery. To increase sample size, a confirmatory group was included, with PRP allowed prior to UWFA but not before diagnosis. In addition, the time between diagnosis and UWFA was increased to 6 months. RESULTS: A total of 11 eyes met inclusion criteria for the primary group. Ischemic index was found to be 91% in the far periphery, 77% in the mid periphery, and 42% at the posterior pole. The total average ischemic index was 76%. There was a statistically significant difference between the far periphery and posterior pole and mid periphery and posterior pole. A total of 24 eyes met criteria for the confirmatory group. Ischemic index for the confirmatory group was found to be 93% in the far periphery, 75% in the mid periphery, and 35% at the posterior pole. There was a statistically significant difference between the far periphery, posterior pole and mid-periphery. CONCLUSION: This knowledge can be used to further guide treatment and understand risk for NVG.

Visual Outcomes in Eyes With Neovascular Glaucoma and Anterior Segment Neovascularization Without Glaucoma.

PURPOSE: To find predictive factors of neovascular glaucoma (NVG) development in eyes with anterior segment neovascularization without glaucoma (ASNVWG), and poor visual outcomes in eyes that have already developed NVG. DESIGN: Retrospective, clinical cohort studies. METHODS: A retrospective chart review was performed on 106 eyes of 94 patients with ASNVWG and 245 eyes of 225 patients with NVG. Measured outcomes included the development of NVG at any time point of the disease for the ASNVWG arm, and a visual acuity of ≤20/200 at 6 months after initial presentation for the NVG arm. RESULTS: Overall, 25% of ASNVWG eyes progressed to NVG. Progression was associated with retinal vein occlusion (RVO) (P < .01), lower median presenting BCVA (P < .01), and concurrent traction retinal detachments (TRDs) (P = .025). Sixty-eight percent of NVG eyes had a BCVA of ≤20/200 by 6-month follow-up, which was associated with RVO (P = .005), vitreous hemorrhage on presentation (P = .001), and no panretinal photocoagulation (PRP) treatments (P < .001). BCVA >20/200 at 6 months was associated with ≥1 PRP or intravitreal bevacizumab (IVB) treatment within 1 week of presentation or ≥3 PRP or IVB treatments overall (P < .001). CONCLUSION: RVO, presenting visual acuity, and concurrent TRD are risk factors for NVG in eyes with ASNVWG. In eyes with NVG, RVO and concurrent vitreous hemorrhage are risk factors for ≤20/200 vision at 6 months, whereas treatment with ≥1 PRP or IVB within 1 week of presentation, or ≥3 treatments of PRP or IVB within 6 months are protective.

Hypertension: A Cause of Bilateral Proliferative Retinopathy.

Purpose: To describe the case of a 67-year-old female with proliferative retinopathy secondary to uncontrolled hypertension. Methods: Retrospective case report including multimodal imaging. Results: A 67-year-old female presented with mild vitreous hemorrhage, retinal hemorrhage, hard exudate of the left eye and hard exudate, copper wiring of vessels, and retinal hemorrhages in the right eye. Optical coherence tomography depicted macular edema of both eyes. Fluorescein angiography revealed large areas of peripheral retinal ischemia and neovascularization with multiple areas of vascular leakage in both eyes. Conclusions: Proliferative hypertensive retinopathy has been rarely reported in the literature. Our patient exhibited findings consistent with proliferative retinopathy secondary to hypertensive retinopathy.

Acquired Vitelliform Macular Degeneration: Characteristics and Challenges of Managing Subretinal Fluid.

PURPOSE: To highlight diagnostic challenges in patients with acquired vitelliform macular degeneration (AVMD) with subretinal fluid (SRF) and to examine the characteristics of image findings in patients with AVMD. METHODS: In this retrospective review, the electronic medical record of 22 eyes of 16 patients with AVMD was studied. The rates of SRF, drusen, pigment epithelial detachment (PED), and patient clinical information such as age, length of follow-up, and best-corrected visual acuity (BCVA) were assessed. RESULTS: The mean age at diagnosis with AVMD was 72 years with a mean follow-up time of 29 months. Median BCVA 20/33 at presentation and 20/33 at final follow-up. Drusen was found in 13 of 22 eyes (59.1%), PEDs in 4 of 22 eyes (18.2%), and SRF in 10 of 22 eyes (45.5%) at some point during their follow-up. Of the 10 eyes with SRF, 70% were center involving, and recurrence occurred in 40%, all in the same location as the initial presentation of SRF. Three eyes received an anti-vascular endothelial growth factor injection for SRF. In 66% of cases receiving an injection, the fluid later relapsed and remitted without further injections during the course of follow-up. CONCLUSION: AVMD occurs in the same demographic as age-related macular degeneration (AMD) and has many common features. SRF in AVMD tends to be center involving and recurs usually in the same location as its origin. The use of anti-VEGF injections did not seem to improve SRF in contrast to the SRF seen in wet AMD. Proper differentiation of AVMD may prevent unnecessary long-term treatment with intravitreal anti-VEGF injections.

Fundus Autofluorescence and Clinical Applications.

Fundus autofluorescence (FAF) has allowed in vivo mapping of retinal metabolic derangements and structural changes not possible with conventional color imaging. Incident light is absorbed by molecules in the fundus, which are excited and in turn emit photons of specific wavelengths that are captured and processed by a sensor to create a metabolic map of the fundus. Studies on the growing number of FAF platforms has shown each may be suited to certain clinical scenarios. Scanning laser ophthalmoscopes, fundus cameras, and modifications of these each have benefits and drawbacks that must be considered before and after imaging to properly interpret the images. Emerging clinical evidence has demonstrated the usefulness of FAF in diagnosis and management of an increasing number of chorioretinal conditions, such as age-related macular degeneration, central serous chorioretinopathy, retinal drug toxicities, and inherited retinal degenerations such as retinitis pigmentosa and Stargardt disease. This article reviews commercial imaging platforms, imaging techniques, and clinical applications of FAF.

Patterns of Autofluorescence in Common Genotypes of Retinitis Pigmentosa.

BACKGROUND AND OBJECTIVE: To investigate whether different forms of retinitis pigmentosa (RP) could be distinguished from one another using fundus autofluorescence (FAF) imaging. PATIENTS AND METHODS: The National Institutes of Health EyeGene database was used to gather FAF images from 31 patients with RP, which were separated into 11 groups based on the RP-associated gene that was mutated. Investigators reviewed the images for patterns of autofluorescence (AF) and recorded qualitative observations. RESULTS: Four patterns of AF were noted within the macula, including central foveal hyper AF, a perifoveal hyper AF ring, a macular hyper AF ring, and a bull's-eye pattern of AF. Four patterns of AF were noted outside of the macula, including a mid-peripheral hyper AF ring, extramacular spots of hyper AF, patches of hypo AF, and diffuse hypo AF in the periphery. Double hyper AF rings were present in RHO, RPGR, USH2A, and NR2E3-linked RP. CONCLUSIONS: Similar patterns of AF were seen in different forms of RP, and AF failed to distinguish different genotypes. [Ophthalmic Surg Lasers Imaging Retina. 2021;52:426-431.].

Association of the Pattern of Retinal Capillary Non-Perfusion and Vascular Leakage with Retinal Neovascularization in Proliferative Diabetic Retinopathy.

PURPOSE: To explore the correlation between retinal capillary non-perfusion and the distribution of retinal neovascularization and vascular leakage (VL) in patients with proliferative diabetic retinopathy (PDR). METHODS: Ultra-widefield angiograms of 96 eyes of 69 patients with PDR were reviewed for the proportion of non-perfused area to total gradable area, and for the presence of neovascularization and VL. RESULTS: Retinal neovascularization was distributed as such: neovascularization elsewhere (NVE), 57.3%; neovascularization of the disc (NVD), 11.5%; both neovascularization of the disc and elsewhere (NVED), 31.3%. The proportion of non-perfused retina, so-called ischemic index, was greater in eyes with NVED compared to eyes with NVE only, but not when compared to NVD only. Overall, 83% of eyes had VL. The presence and the extent of VL correlated with the proportion of the ischemic index. While VL and ischemic index were more severe in the mid-periphery and far-periphery, the majority of NVE was located in the posterior pole. CONCLUSIONS: The presence of both NVD and NVE is associated with a greater ischemic index than NVE alone. Although both VL and ischemic index is significantly higher in peripheral zones, the majority of neovascularization occurs at the posterior pole.

Relating Retinal Vascular Oxygen Saturation and Microvasculature Morphology at Progressive Stages of Diabetic Retinopathy.

Purpose: Diabetic retinopathy (DR) is a common cause of vision loss in working age adults and presents changes in retinal vessel oxygenation and morphology. The purpose of this study was to test the hypothesis that there is an association of retinal vessel oxygen saturation with vessel density (VD) and tortuosity in DR. Methods: Ninety-five subjects were classified in the following groups: nondiabetic control (N = 25), no DR (N = 28), mild nonproliferative DR (NPDR; N = 21), moderate to severe NPDR (N = 14), or treated proliferative DR (PDR; N = 7). Retinal oximetry was performed to measure arterial and venous oxygen saturation (SO2A and SO2V) and calculate oxygen extraction fraction (OEF). Optical coherence tomography angiography (OCTA) was performed for measurements of VD and vessel tortuosity index (VTI). Results: There were statistically significant differences in SO2A and SO2V among groups (P ≤ 0.004). SO2A and SO2V were higher in the PDR group compared to the control group and SO2V was also higher in the moderate to severe NPDR group. VD differed significantly among groups (P = 0.003), whereas VTI was not significantly different (P = 0.22). Compared to the control group, VD was lower in moderate to severe NPDR and PDR groups. VD was also lower in the PDR group than that in the no DR group (P = 0.03). There was a significant correlation of VTI with SO2V (r = 0.32, P = 0.002) and OEF (r = -0.35, P = 0.001). Conclusions: Retinal vessel morphology, oxygenation, and tissue oxygen extraction were associated with each other in a cohort of subjects with and without DR. Translational Relevance: The findings of this study have the potential to improve clinical management of DR by providing better understanding of human disease pathophysiology and propelling future studies to identify multiple image-based biomarkers for improved disease diagnosis and monitoring.