CHOROIDAL VASCULAR ALTERATIONS IN AGE-RELATED MACULAR DEGENERATION AND POLYPOIDAL CHOROIDAL VASCULOPATHY.

PURPOSE: To evaluate morphologic alterations in choroidal veins in eyes with typical neovascular age-related macular degeneration (nAMD) and polypoidal choroidal vasculopathy (PCV). METHODS: A retrospective review of baseline indocyanine green angiography in eyes with typical nAMD and PCV. We evaluated Haller layer veins in the early-phase indocyanine green angiography (before 2 minutes) for 1) macular anastomosis, 2) dilated Haller veins, and 3) focal variation in vessel caliber by at least 50% from the narrowest to largest diameters. RESULTS: We included 70 patients with gradable indocyanine green angiography for the prespecified features in the study eye (36 typical nAMD and 34 PCV) and 59 fellow eyes. The median subfoveal choroidal thickness was 167 µm versus 219 µm, P = 0.08, in the presenting eyes in typical nAMD and PCV, respectively. Macular anastomosis was common in both typical nAMD and PCV (presenting eyes 58.3% vs. 58.8%. P = 0.97; fellow eyes 65.5% vs. 63.3%, P = 0.86). Dilated Haller veins were numerically less common in typical nAMD than PCV (presenting eyes 52.8% vs. 67.6%, P = 0.21; fellow eyes 65.5% vs. 70.0%, P = 0.71), while vascular caliber variation was numerically more common in typical nAMD than PCV (presenting eyes 72.2% vs. 63.8%, P = 0.45; fellow eyes 69.0% vs. 56.7%, P = 0.33). The presence of all three features was more common in the presenting eyes with PCV compared with typical nAMD (35.3% vs. 13.9%, P = 0.03). In a multivariable analysis, every increase of 100 µm of CT conferred a 2.75 risk of having all three features present. CONCLUSION: Choroidal vascular remodeling is common in both tAMD and PCV but may be driven by different stimuli.

FIVE-YEAR INCIDENCE OF FELLOW EYE NEOVASCULAR INVOLVEMENT IN AGE-RELATED MACULAR DEGENERATION AND POLYPOIDAL CHOROIDAL VASCULOPATHY IN AN ASIAN POPULATION.

PURPOSE: To assess 5-year cumulative incidence and risk factors of fellow eye involvement in Asian neovascular age-related macular degeneration (nAMD) and polypoidal choroidal vasculopathy. METHODS: In a prospective cohort study of Asian nAMD and polypoidal choroidal vasculopathy, the fellow eyes were evaluated for exudation. The 5-year incidence of exudation was compared between nAMD and polypoidal choroidal vasculopathy. RESULTS: A total of 488 patients were studied. The 5-year incidence of exudation in fellow eyes was 16.2% (95% confidence interval: 12.0-20.2). Polypoidal choroidal vasculopathy compared with nAMD in the first eye was associated with lower fellow eye progression (9.8% [95% confidence interval: 5.1-14.3]) vs. 22.9% [95% confidence interval: 15.8-29.3], P < 0.01). Drusen (hazards ratio 2.11 [95% confidence interval: 1.10-4.06]), shallow irregular retinal pigment epithelium elevation (2.86 [1.58-5.18]), and pigment epithelial detachment (3.01 [1.27-7.17]) were associated with greater progression. A combination of soft drusens and subretinal drusenoid deposits, and specific pigment epithelial detachment subtypes (multilobular, and sharp peaked) were associated with progression. Pigment epithelial detachment, shallow irregular retinal pigment epithelium elevation, and new subretinal hyperreflective material occurred at 10.4 ± 4.2 months, 11.1 ± 6.0 months, and 6.9 ± 4.3 months, respectively, before exudation. CONCLUSION: The 5-year incidence of fellow eye involvement in Asian nAMD is lower than among Caucasians because of a higher polypoidal choroidal vasculopathy prevalence. Drusens, shallow irregular retinal pigment epithelium elevation, and pigment epithelial detachment are risk factors for fellow eye progression.

PATTERN AND CHARACTERISTICS OF DRUSEN SUBTYPES IN CHINESE AND INDIAN POPULATIONS IN SINGAPORE.

PURPOSE: To report the pattern and characteristics of drusen subtypes in Asian populations and the association with choroidal thickness. METHODS: This is the cross-sectional analysis of the population-based cohort study. Two thousand three hundred and fifty-three eyes of 1,336 Chinese and Indian participants aged older than 50 years, eyes with best-corrected visual acuity better than 20/60, and without other retinal diseases were recruited. Pachydrusen, reticular pseudodrusen, soft and hard drusen were graded on both color fundus photographs, and optical coherence tomography imaging with automated segmentation yielding and measurements of choroidal thickness. RESULTS: Nine hundred and fifty-five Chinese and 381 Indians were included in the final analysis. The pattern of pachydrusen, soft drusen, hard drusen, and reticular pseudodrusen was 14.0%, 3.7%, 12.5%, and 0.2%, respectively. Mean choroidal thickness was the thickest in eyes with pachydrusen (298.3 µm; 95% confidence interval: 290.5-306.1), then eyes with hard (298.1 µm; 95% confidence interval: 290.6-305.5) and soft drusen (293.7 µm; 95% confidence interval: 281.9-305.4) and thinnest in eyes without drusen (284.6 µm; 95% confidence interval: 280.5-288.7). Systemic associations of the various drusen subtypes also differed. CONCLUSION: Patterns, characterization and choroidal thickness of drusen subtypes, and their associations provide insights into the Asian phenotypic spectrum of age-related macular degeneration and the underlying pathogenesis.

OPTICAL COHERENCE TOMOGRAPHY FEATURES OF POLYPOIDAL LESION CLOSURE IN POLYPOIDAL CHOROIDAL VASCULOPATHY TREATED WITH AFLIBERCEPT.

PURPOSE: To evaluate whether optical coherence tomography (OCT) can determine polypoidal lesion (PL) perfusion in polypoidal choroidal vasculopathy eyes after 12 months of aflibercept monotherapy. Polypoidal lesion perfusion status, assessed by indocyanine green angiography, is an important anatomical outcome in polypoidal choroidal vasculopathy management. METHODS: Post hoc data from a prospective randomized, open-label, study in eyes with polypoidal choroidal vasculopathy undergoing monotherapy with aflibercept evaluated PL perfusion status based on indocyanine green angiography (gold standard) and OCT features from baseline to 12 months. RESULTS: Individual PLs (110 in total) from 48 eyes (48 patients) showed at 12 months; 57/110 PLs (51.8%) were closed on indocyanine green angiography. At 12 months, eyes with closed PLs were more likely to have the following OCT features: 1) no subretinal fluid (67.1% vs. 32.9%), 2) smaller pigment epithelial detachment height (67.2 [±43.8] vs. 189.2 [±104.9] µm), 3) densely hyperreflective pigment epithelial detachment contents (84.0% vs. 16.0%), 4) an absence of a hyperreflective ring(64.0% vs. 36.0%), and a 5) indistinct overlying retinal pigment epithelial (71.4% vs. 28.6%) (all P < 0.05). The three highest performing OCT features that differentiated perfused from closed PLs were (1), (3), and (4) (area under the receiver operating characteristic curve 0.85, 0.73, and 0.70, respectively). A combination of these three features achieved an area under the receiver operating characteristic curve of 0.90. CONCLUSION: Polypoidal lesion closure, an important anatomical treatment outcome in polypoidal choroidal vasculopathy typically defined by indocyanine green angiography, can be accurately detected by specific OCT features.

PULSATILE FILLING OF DILATED CHOROIDAL VESSELS IN MACULAR WATERSHED ZONES.

PURPOSE: To describe pulsatile filling of dilated choroidal veins in the watershed zones and propose an alteration in choroidal perfusion pressure. METHODS: Retrospective review of original and digital subtraction indocyanine green angiography. RESULTS: We observed pulsating blood flow within choroidal vein segments in the posterior pole in 14 eyes (diagnosis of polypoidal choroidal vasculopathy, central serous chorioretinopathy, or neovascular age-related macular degeneration). Pulsating dye front was observed in single or multiple large choroidal vein(s) in a location that is ordinarily a watershed zone between the segmental areas of venous drainage, and vessels proximal and distal were often dilated. The pulsatile venous segments filled more slowly than the neighboring veins. In digital subtraction indocyanine green angiography, the dye front advanced in an incremental fashion or oscillated in a back-and-forth manner during several cardiac cycles during the filling of these larger choroidal veins. With indocyanine green angiography, we observed dilated choroidal veins that violated the macula watershed zone, localized bulbous dilations, and arteriole-over-vein crossings with apparent compression. CONCLUSION: These novel observations suggest the pressure gradient for flow in the affected veins varied from low gradients when the filling was slow to high gradients when the filling was faster. The vessels violated the physiological watershed zone and seem to function as anastomoses between the ordinarily segmented venous drainage of the choroid. The dilated segments may result in pooling of venous blood as part of venous outflow abnormalities that may be operative in these diseases.

POLYPOIDAL CHOROIDAL VASCULOPATHY FEATURES VARY ACCORDING TO SUBFOVEAL CHOROIDAL THICKNESS.

PURPOSE: To evaluate associations between choroidal thickness and features of polypoidal choroidal vasculopathy (PCV) lesions based on multimodal imaging. METHODS: This cross-sectional analysis included treatment-naive PCV eyes from a prospectively recruited observational cohort. Associations between of subfoveal choroidal thickness (SFCT) and qualitative and quantitative morphologic features of PCV lesions on color fundus photographs, indocyanine green and fluorescein angiography, and spectral-domain optical coherence tomography were evaluated. RESULTS: We included 100 eyes with indocyanine green angiography-proven PCV. Subfoveal choroidal thickness showed a bimodal distribution with peaks at 170 µm and 350 µm. There was a significant linear increase in the total lesion area (P-trend = 0.028) and the polypoidal lesion area (P-trend = 0.030 and P-continuous = 0.037) with increasing SFCT. Pairwise comparisons between quartiles showed that the total lesion area (4.20 ± 2.61 vs. 2.89 ± 1.43 mm2, P = 0.024) and the polypoidal lesion area (1.03 ± 1.01 vs. 0.59 ± 0.45 mm2, P = 0.042) are significantly larger in eyes in Q4 (SFCT ≥ 350 µm) than eyes in Q1 (SFCT ≤ 170 µm). Although there was no significant linear trend relating SFCT to best-corrected visual acuity, pairwise comparisons showed that eyes in Q4 (SFCT ≥ 350 µm) have significantly worse vision (0.85 ± 0.63 vs. 0.55 ± 0.27 logMAR, P = 0.030) than eyes in Q2 (SFCT 170-260 µm). CONCLUSION: Total lesion areas and polypoidal lesion areas tend to be larger in eyes with increasing SFCT. Choroidal background may influence the phenotype or progression pattern of PCV.

Association between retinal thickness variation and visual acuity change in neovascular age-related macular degeneration.

BACKGROUND: To assess the association between variation in retinal central subfield thickness (CSFT) with best-corrected visual acuity (BCVA) change in patients receiving vascular endothelial growth factor (VEGF) inhibitor therapy for neovascular age-related macular degeneration (nAMD). METHODS: CSFT measurements were obtained from 141 eyes (total 1300 scans). SD of CSFT was calculated. The eyes were categorised into CSFT variation tertiles. Multiple linear regression was used to examine the association between the CSFT tertiles and BCVA change at 12 mo, adjusting for differences in baseline demographic and clinical characteristics. RESULTS: At 12 mo, the mean BCVA of the high CSFT variation group (50.6 letters) was significantly lower than the low and moderate CSFT variation groups (57.5 and 59.8 letters, respectively), P = .02. The adjusted mean BCVA gains were +1.7, +7.2, and +7.8 letters in the high, moderate and low CSFT variation groups, respectively (P = .03). CONCLUSIONS: A greater variation in retinal thickness during VEGF inhibitor therapy for nAMD is associated with a less favourable visual outcome. CSFT stability is useful in prognosticating visual outcomes in VEGF inhibitor therapy for nAMD.

Preclinical and clinical studies of photobiomodulation therapy for macular oedema.

AIMS/HYPOTHESIS: Diabetic macular oedema (DME) is the leading cause of visual impairment in people with diabetes. Intravitreal injections of vascular endothelial growth factor inhibitors or corticosteroids prevent loss of vision by reducing DME, but the injections must be given frequently and usually for years. Here we report laboratory and clinical studies on the safety and efficacy of 670 nm photobiomodulation (PBM) for treatment of centre-involving DME. METHODS: The therapeutic effect of PBM delivered via a light-emitting diode (LED) device was tested in transgenic mice in which induced Müller cell disruption led to photoreceptor degeneration and retinal vascular leakage. We also developed a purpose-built 670 nm retinal laser for PBM to treat DME in humans. The effect of laser-delivered PBM on improving mitochondrial function and protecting against oxidative stress was studied in cultured rat Müller cells and its safety was studied in pigmented and non-pigmented rat eyes. We then used the retinal laser to perform PBM in an open-label, dose-escalation Phase IIa clinical trial involving 21 patients with centre-involving DME. Patients received 12 sessions of PBM over 5 weeks for 90 s per treatment at a setting of 25, 100 or 200 mW/cm2 for the three sequential cohorts of 6-8 patients each. Patients were recruited from the Sydney Eye Hospital, over the age of 18 and had centre-involving DME with central macular thickness (CMT) of >300 µm with visual acuity of 75-35 Log minimum angle of resolution (logMAR) letters (Snellen visual acuity equivalent of 20/30-20/200). The objective of this trial was to assess the safety and efficacy of laser-delivered PBM at 2 and 6 months. The primary efficacy outcome was change in CMT at 2 and 6 months. RESULTS: LED-delivered PBM enhanced photoreceptor mitochondrial membrane potential, protected Müller cells and photoreceptors from damage and reduced retinal vascular leakage resulting from induced Müller cell disruption in transgenic mice. PBM delivered via the retinal laser enhanced mitochondrial function and protected against oxidative stress in cultured Müller cells. Laser-delivered PBM did not damage the retina in pigmented rat eyes at 100 mW/cm2. The completed clinical trial found a significant reduction in CMT at 2 months by 59 ± 46 µm (p = 0.03 at 200 mW/cm2) and significant reduction at all three settings at 6 months (25 mW/cm2: 53 ± 24 µm, p = 0.04; 100 mW/cm2: 129 ± 51 µm, p < 0.01; 200 mW/cm2: 114 ± 60 µm, p < 0.01). Laser-delivered PBM was well tolerated in humans at settings up to 200 mW/cm2 with no significant side effects. CONCLUSIONS/INTERPRETATION: PBM results in anatomical improvement of DME over 6 months and may represent a safe and non-invasive treatment. Further testing is warranted in randomised clinical trials. TRIAL REGISTRATION: ClinicalTrials.gov NCT02181400 Graphical abstract.

PREVALENCE AND RISK FACTORS FOR THE DEVELOPMENT OF PHYSICIAN-GRADED SUBRETINAL FIBROSIS IN EYES TREATED FOR NEOVASCULAR AGE-RELATED MACULAR DEGENERATION.

PURPOSE: To assess the prevalence and incidence of and risk factors for subretinal fibrosis (SRFi) in eyes with neovascular age-related macular degeneration (nAMD) that underwent vascular endothelial growth factor inhibitor treatment for up to 10 years. METHODS: A cross-sectional and longitudinal analysis was performed on data from a neovascular age-related macular degeneration registry. The presence and location of SRFi were graded by the treating practitioner. Visual acuity, lesion characteristics (type, morphology, and activity), and treatment administered at each visit was recorded. RESULTS: The prevalence of SRFi in 2,914 eyes rose from 20.4% at year interval 0-1 to 40.7% at year interval 9 to 10. The incidence in 1,950 eyes was 14.3% at baseline and 26.3% at 24 months. Independent characteristics associated with SRFi included poorer baseline vision (adjusted odds ratio 5.33 [95% confidence interval 4.66-7.61] for visual acuity ≤35 letters vs. visual acuity ≥70 letters, P < 0.01), baseline lesion size (adjusted odds ratio 1.08 [95% confidence interval 1.08-1.14] per 1000 µm, P = 0.03), lesion type (adjusted odds ratio 1.42 [95% confidence interval 1.17-1.72] for predominantly classic vs. occult lesions, P = 0.02), and proportion of active visits (adjusted odds ratio 1.58 [95% confidence interval 1.25-2.01] for the group with the highest level of activity vs. the lowest level of activity, P < 0.01). CONCLUSION: Subretinal fibrosis was found in 40% of eyes after 10 years of treatment. High rates of lesion activity, predominantly classic lesions, poor baseline vision, and larger lesion size seem to be independent risk factors for SRFi.

COMPARISON OF OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHIC CHANGES AFTER ANTI-VASCULAR ENDOTHELIAL GROWTH FACTOR THERAPY ALONE OR IN COMBINATION WITH PHOTODYNAMIC THERAPY IN POLYPOIDAL CHOROIDAL VASCULOPATHY.

PURPOSE: To compare changes in optical coherence tomography angiography in eyes with polypoidal choroidal vasculopathy after treatment with anti-vascular endothelial growth factor monotherapy or combined with photodynamic therapy. METHODS: This is a longitudinal case-controlled study. The authors performed optical coherence tomography angiography at baseline and Month 3 in patients with treatment-naive polypoidal choroidal vasculopathy undergoing monotherapy (n = 10) or combination therapy (n = 13). We analyzed flow signal within the outer retina and choriocapillaris using automated segmentation. The authors analyzed the presence of pachyvessels using a 10.4-µm segment through Haller layer. The changes in each layer were compared between treatments. RESULTS: At Month 3, both groups showed similar improvement in best-corrected visual acuity and central retinal thickness. However, flow signal within the polypoidal choroidal vasculopathy complex was decreased in more eyes after combination therapy than after monotherapy (84.6% vs. 40.0%, P = 0.04). Patchy reduction in flow signal within the choriocapillaris layer was noted in 15.4% and 10.0% after combination therapy and monotherapy, respectively (P = 0.61). Significant reduction in pachyvessel caliber was seen only after combination therapy but not after monotherapy (75.0% vs. 0.0%, P = 0.01). CONCLUSION: Longitudinal optical coherence tomography angiography demonstrates more significant reduction in lesion flow and pachyvessels in the short term after combination therapy than after monotherapy, although visual and structural OCT showed similar improvement.

The Use of Vascular Endothelial Growth Factor Inhibitors and Complementary Treatment Options in Polypoidal Choroidal Vasculopathy: A Subtype of Neovascular Age-Related Macular Degeneration.

Polypoidal choroidal vasculopathy (PCV) is a subtype of neovascular age-related macular degeneration (AMD; nAMD) which occurs more commonly in Asian populations as compared to Caucasians. PCV and nAMD share pathological mechanisms, including pathological expression of vascular endothelial growth factor (VEGF). The advent of anti-vascular endothelial growth factor (VEGF) revolutionized the treatment of nAMD. Despite being a subtype of nAMD, PCV responds less well to VEGF inhibitors; thus, photodynamic therapy (PDT) in combination with anti-VEGF treatment may be considered. This review aims to summarize the current evidence for the treatment of PCV, especially whether VEGF inhibitors should be used alone or in combination with PDT.

Pneumatic displacement of submacular haemorrhage secondary to neovascular age-related macular degeneration and polypoidal choroidal vasculopathy.

BACKGROUND: To compare the visual and anatomical outcomes of pneumatic displacement (PD) combined with anti-vascular endothelial growth factor (VEGF) therapy versus anti-VEGF monotherapy in treatment-naive eyes with submacular haemorrhage (SMH) secondary to neovascular age-related macular degeneration and polypoidal choroidal vasculopathy. METHODS: In a retrospective comparative interventional study of 57 eyes, the changes in logMAR visual acuity (VA), and SMH height and area at baseline at months 1, 3 and 12 were compared between the PD and non-PD groups. RESULTS: There was no significant difference in mean VA in the PD versus non-PD group at month 12 (1.1 versus 0.7, p = 0.09). At baseline, the PD group, compared to the non-PD group, had significantly larger SMH area (35.9 versus 26.9 mm2, p = 0.04) and SMH height at the fovea (733.7 versus 503.6 µm, p < 0.01). The greatest reduction in SMH height and area occurred between baseline and month 1 in the PD group, which was faster than between month 1 and month 3 in the non-PD group, with similar findings in the matched pair analysis matched for SMH height and area. In the multivariable analysis, only baseline VA was associated with VA outcomes (month 1: ß = -0.46, 95% [confidence interval] CI = -0.78 to -0.14, p = 0.006; month 3: ß = -0.52, 95% CI = -0.86 to -0.18, p = 0.004; and month 12: ß = -0.78, 95% CI = -1.16 to -0.39, p < 0.001). CONCLUSIONS: The visual outcome of SMH at month 12 in nAMD and PCV is poor regardless of whether PD is performed in addition to anti-VEGF therapy, although a more rapid resolution of SMH can be expected.

Six-Year Outcomes in Subjects with Polypoidal Choroidal Vasculopathy in the EVEREST II Study.

INTRODUCTION: The EVEREST II study previously reported that intravitreally administered ranibizumab (IVR) combined with photodynamic therapy (PDT) achieved superior visual gain and polypoidal lesion closure compared to IVR alone in patients with polypoidal choroidal vasculopathy (PCV). This follow-up study reports the long-term outcomes 6 years after initiation of the EVEREST II study. METHODS: This is a non-interventional cohort study of 90 patients with PCV from 16 international trial sites who originally completed the EVEREST II study. The long-term outcomes were assessed during a recall visit at about 6 years from commencement of EVEREST II. RESULTS: The monotherapy and combination groups contained 41 and 49 participants, respectively. The change in best-corrected visual acuity (BCVA) from baseline to year 6 was not different between the monotherapy and combination groups; - 7.4 ± 23.0 versus - 6.1 ± 22.4 letters, respectively. The combination group had greater central subfield thickness (CST) reduction compared to the monotherapy group at year 6 (- 179.9 vs - 74.2 µm, p = 0.011). Fewer eyes had subretinal fluid (SRF)/intraretinal fluid (IRF) in the combination versus monotherapy group at year 6 (35.4% vs 57.5%, p = 0.032). Factors associated with BCVA at year 6 include BCVA (year 2), CST (year 2), presence of SRF/IRF at year 2, and number of anti-VEGF treatments (years 2-6). Factors associated with presence of SRF/IRF at year 6 include combination arm (OR 0.45, p = 0.033), BCVA (year 2) (OR 1.53, p = 0.046), and presence of SRF/IRF (year 2) (OR 2.59, p = 0.042). CONCLUSION: At 6 years following the EVEREST II study, one-third of participants still maintained good vision. As most participants continued to require treatment after exiting the initial trial, ongoing monitoring and re-treatment regardless of polypoidal lesion status are necessary in PCV. TRIAL REGISTRATION: ClinicalTrials.gov identifier, NCT01846273.

Review of Fibrosis in Neovascular Age-Related Macular Degeneration.

PURPOSE: To report the diagnosis and definitions, epidemiology, risk factors, and visual outcomes of fibrosis in neovascular age-related macular degeneration (nAMD). DESIGN: Systematic review and meta-analysis. METHODS: The review was performed using the Cochrane Handbook and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Observational studies and randomized controlled trials were included. RESULTS: Identification of fibrosis is challenging. Optical coherence tomography angiography and polarization-sensitive optical coherence tomography represent novel options in multimodal imaging. The prevalence of fibrosis at baseline, 12, 24, and 60 months was 13%, 32%, 36%, and 56%, respectively. Approximately 60% of the fibrosis burden in nAMD at 5 years was present in the first year of treatment. Fibrosis development was highest in the first 12 months and slowed down over time. The risk factors of fibrosis included classic choroidal neovascularization (CNV), intra-retinal fluid, hemorrhage, hyperreflective material, CNV lesion size, and retinal thickness. Sub-retinal fluid and pigment epithelial detachment may be protective. Treatment-associated factors included disease activity and time to diagnosis. At baseline, the best corrected visual acuity in eyes with fibrosis was poorer than in eyes without fibrosis (-18.50 letters); this difference became larger at 12 months despite treatment (-26.86 letters). CONCLUSIONS: There is a need to identify effective treatment strategies for fibrosis and to closely monitor at-risk patients. More studies involving multimodal imaging are required to clarify the definitions and grading criteria for fibrosis.

Clinical utility of ultra-widefield fluorescein angiography and optical coherence tomography angiography for retinal vein occlusions.

Retinal vein occlusions (RVOs) are the second most common retinal vascular disease after diabetic retinopathy, and are a significant cause of visual impairment, especially in the elderly population. RVOs result in visual loss due to macular ischemia, cystoid macular edema (CME), and complications related to neovascularization. Vascular assessment in RVOs traditionally relies on standard fluorescein angiography (FA) for assessment of macular and retinal ischemia, which aids in prognostication and guides intervention. Standard FA has significant limitations-it is time-consuming, requires invasive dye administration, allows for limited assessment of the peripheral retina, and is usually evaluated semi-qualitatively, by ophthalmologists with tertiary expertise. More recently, the introduction of ultra-widefield FA (UWF FA) and optical coherence tomography angiography (OCTA) into clinical practice has changed the tools available for vascular evaluation in RVOs. UWF FA allows for evaluation of peripheral retinal perfusion, and OCTA is non-invasive, rapidly-acquired, and provides more information on capillary perfusion. Both modalities can be used to provide more quantitative parameters related to retinal perfusion. In this article, we review the clinical utility and impact of UWF FA and OCTA in the evaluation and management of patients with RVOs.

Optical Coherence Tomography Angiography in Retinal Vascular Disorders.

Traditionally, abnormalities of the retinal vasculature and perfusion in retinal vascular disorders, such as diabetic retinopathy and retinal vascular occlusions, have been visualized with dye-based fluorescein angiography (FA). Optical coherence tomography angiography (OCTA) is a newer, alternative modality for imaging the retinal vasculature, which has some advantages over FA, such as its dye-free, non-invasive nature, and depth resolution. The depth resolution of OCTA allows for characterization of the retinal microvasculature in distinct anatomic layers, and commercial OCTA platforms also provide automated quantitative vascular and perfusion metrics. Quantitative and qualitative OCTA analysis in various retinal vascular disorders has facilitated the detection of pre-clinical vascular changes, greater understanding of known clinical signs, and the development of imaging biomarkers to prognosticate and guide treatment. With further technological improvements, such as a greater field of view and better image quality processing algorithms, it is likely that OCTA will play an integral role in the study and management of retinal vascular disorders. Artificial intelligence methods-in particular, deep learning-show promise in refining the insights to be gained from the use of OCTA in retinal vascular disorders. This review aims to summarize the current literature on this imaging modality in relation to common retinal vascular disorders.

Review of Retinal Imaging Modalities for Hydroxychloroquine Retinopathy.

This review provides an overview of conventional and novel retinal imaging modalities for hydroxychloroquine (HCQ) retinopathy. HCQ retinopathy is a form of toxic retinopathy resulting from HCQ use for a variety of autoimmune diseases, such as rheumatoid arthritis and systemic lupus erythematosus. Each imaging modality detects a different aspect of HCQ retinopathy and shows a unique complement of structural changes. Conventionally, spectral-domain optical coherence tomography (SD-OCT), which shows loss or attenuation of the outer retina and/or retinal pigment epithelium-Bruch's membrane complex, and fundus autofluorescence (FAF), which shows parafoveal or pericentral abnormalities, are used to assess HCQ retinopathy. Additionally, several variations of OCT (retinal and choroidal thickness measurements, choroidal vascularity index, widefield OCT, en face imaging, minimum intensity analysis, and artificial intelligence techniques) and FAF techniques (quantitative FAF, near-infrared FAF, fluorescence lifetime imaging ophthalmoscopy, and widefield FAF) have been applied to assess HCQ retinopathy. Other novel retinal imaging techniques that are being studied for early detection of HCQ retinopathy include OCT angiography, multicolour imaging, adaptive optics, and retromode imaging, although further testing is required for validation.

Relationship Between Retinal Layer Thickness and Genetic Susceptibility to Age-Related Macular Degeneration in Asian Populations.

Purpose: For OCT retinal thickness measurements to be used as a prodromal age-related macular degeneration (AMD) risk marker, the 3-dimensional (3D) topographic variation of the relationship between genetic susceptibility to AMD and retinal thickness needs to be assessed. We aimed to evaluate individual retinal layer thickness changes and topography at the macula that are associated with AMD genetic susceptibility. Design: Genetic association study. Participants: A total of 1579 healthy participants (782 Chinese, 353 Malays, and 444 Indians) from the multiethnic Singapore Epidemiology of Eye Diseases study were included. Methods: Spectral-domain OCT and automatic segmentation of individual retinal layers were performed to produce 10 retinal layer thickness measurements at each ETDRS subfield, producing 3D topographic information. Age-related macular degeneration genetic susceptibility was represented via single nucleotide polymorphisms (SNPs) and aggregated via whole genome (overall) and pathway-specific age-related macular degeneration polygenic risk score (PRSAMD). Main Outcome Measures: Associations of individual SNPs, overall PRSAMD, and pathway-specific PRSAMD with retinal thickness were analyzed by individual retinal layer and ETDRS subfield. Results: CFH rs10922109, ARMS2-HTRA1 rs3750846, and LIPC rs2043085 were the top AMD susceptibility SNPs associated with retinal thickness of individual layers (P < 1.67 × 10-3), all at the central subfield. The overall PRSAMD was most associated with thinner L9 (outer segment photoreceptor/retinal pigment epithelium complex) thickness at the central subfield (ß = -0.63 µm; P = 5.45 × 10-9). Pathway-specific PRSAMD for the complement cascade (ß = -0.53 µm; P = 9.42 × 10-7) and lipoprotein metabolism (ß = -0.05 µm; P = 0.0061) were associated with thinner photoreceptor layers (L9 and L7 [photoreceptor inner/outer segments], respectively) at the central subfield. The mean PRSAMD score was larger among Indians compared with that of the Chinese and had the thinnest thickness at the L9 central subfield (ß = -1.00 µm; P = 2.91 × 10-7; R2 = 5.5%). Associations at other retinal layers and ETDRS regions were more heterogeneous. Conclusions: Overall genetic susceptibility to AMD and the aggregate effects of the complement cascade and lipoprotein metabolism pathway are associated most significantly with L7 and L9 photoreceptor thinning at the central macula in healthy individuals. Photoreceptor thinning has potential to be a prodromal AMD risk marker, and topographic variation should be considered. Financial Disclosures: Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Evaluating the outcome of screening for glaucoma using colour fundus photography-based referral criteria in a teleophthalmology screening programme for diabetic retinopathy.

AIMS: To evaluate the effectiveness of glaucoma screening using glaucoma suspect (GS) referral criteria assessed on colour fundus photographs in Singapore's Integrated Diabetic Retinopathy Programme (SiDRP). METHODS: A case-control study. This study included diabetic subjects who were referred from SiDRP with and without GS between January 2017 and December 2018 and reviewed at Singapore National Eye Centre. The GS referral criteria were based on the presence of a vertical cup-to-disc ratio (VCDR) of ≥0.65 and other GS features. The final glaucoma diagnosis confirmed from electronic medical records was retrospectively matched with GS status. The sensitivity, specificity and positive predictive value (PPV) of the test were evaluated. RESULTS: Of 5023 patients (2625 with GS and 2398 without GS) reviewed for glaucoma, 451 (9.0%, 95% CI 8.2% to 9.8%) were confirmed as glaucoma. The average follow-up time was 21.5±10.2 months. Using our current GS referral criteria, the sensitivity, specificity and PPV were 81.6% (95% CI 77.7% to 85.1%), 50.6% (95% CI 49.2% to 52.1%) and 14.0% (95% CI 13.4% to 14.7%), respectively, resulting in 2257 false positive cases. Increasing the VCDR cut-off for referral to ≥0.80, the specificity increased to 93.9% (95% CI 93.1% to 94.5%) but the sensitivity decreased to 11.3% (95% CI 8.5% to 14.6%), with a PPV of 15.4% (95% CI 12.0% to 19.4%). CONCLUSIONS: Opportunistic screening for glaucoma in a lower VCDR group could result in a high number of unnecessary referrals. If healthcare infrastructures are limited, targeting case findings on a larger VCDR group with high specificity will still be beneficial.

Contribution of common and rare variants to Asian neovascular age-related macular degeneration subtypes.

Neovascular age-related macular degeneration (nAMD), along with its clinical subtype known as polypoidal choroidal vasculopathy (PCV), are among the leading causes of vision loss in elderly Asians. In a genome-wide association study (GWAS) comprising 3,128 nAMD (1,555 PCV and 1,573 typical nAMD), and 5,493 controls of East Asian ancestry, we identify twelve loci, of which four are novel ([Formula: see text]). Substantial genetic sharing between PCV and typical nAMD is noted (rg = 0.666), whereas collagen extracellular matrix and fibrosis-related pathways are more pronounced for PCV. Whole-exome sequencing in 259 PCV patients revealed functional rare variants burden in collagen type I alpha 1 chain gene (COL1A1; [Formula: see text]) and potential enrichment of functional rare mutations at AMD-associated loci. At the GATA binding protein 5 (GATA5) locus, the most significant GWAS novel loci, the expressions of genes including laminin subunit alpha 5 (Lama5), mitochondrial ribosome associated GTPase 2 (Mtg2), and collagen type IX alpha 3 chain (Col9A3), are significantly induced during retinal angiogenesis and subretinal fibrosis in murine models. Furthermore, retinoic acid increased the expression of LAMA5 and MTG2 in vitro. Taken together, our data provide insights into the genetic basis of AMD pathogenesis in the Asian population.