MULTISCALE CORRELATION OF MICROVASCULAR CHANGES ON OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY WITH RETINAL SENSITIVITY IN DIABETIC RETINOPATHY.

PURPOSE: To assess global, zonal, and local correlations between vessel density changes measured by optical coherence tomography angiography and retinal sensitivity measured by microperimetry across diabetic retinopathy severity. METHODS: Diabetic patients and nondiabetic controls underwent optical coherence tomography angiography imaging and microperimetry testing. Pearson's correlation was used to assess associations between average sensitivity and skeletonized vessel density (SVD) or foveal avascular zone area centrally. Linear mixed effects modeling was used to assess relationships between local SVD measurements and their spatially corresponding retinal sensitivity measurements. RESULTS: Thirty-nine eyes from 39 participants were imaged. In all slabs, there was a statistically significant positive correlation between retinal sensitivities and SVDs on both global and zonal scales. No statistically significant correlation was found between central retinal sensitivities and the foveal avascular zone areas. Assessment of 1,136 spatially paired retinal sensitivity and SVD measurements revealed a statistically significant local relationship; this seemed to be driven by eyes with proliferative diabetic retinopathy that had reduced retinal sensitivities. CONCLUSION: This study supports positive correlations between SVD and retinal sensitivity at global and zonal spatial scales in diabetic eyes. However, our analysis did not find evidence of statistically significant correlations between retinal sensitivity and SVD on a local scale until advanced diabetic retinopathy.

SWEPT-SOURCE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY IN SMALL CHOROIDAL MELANOMAS AND CHOROIDAL NEVI.

PURPOSE: To evaluate the use of swept-source optical coherence tomography angiography to detect distinct vascular features in small choroidal melanomas and choroidal nevi. METHODS: Patients with a choroidal nevus or a treatment-naïve choroidal melanoma were imaged with color fundus photography, ultrasound, and swept-source optical coherence tomography angiography (12 × 12 mm). High-risk features including overlying fluid, orange pigment, shaggy photoreceptors, acoustic hollowness, depth >2 mm, and basal diameter >5 mm were assessed. Optical coherence tomography angiography vascular markers included: choroidal vessel visualization, choroidal vessel depth, and choriocapillaris flow signal, assessed qualitatively by comparison with surrounding, unaffected choriocapillaris. RESULTS: Twenty-nine lesions were included in this study, seven flat choroidal nevi, 17 elevated choroidal nevi, and 5 choroidal melanomas. Distinct vascular patterns were noted between flat nevi, elevated nevi, and small choroidal melanomas. Choroidal melanomas displayed two types of vasculature: "nevus-like" vasculature with straight parallel vessels and complex vasculature with vascular loops and crosslinking. Visualized choroidal vessels were significantly deeper in melanomas (110 µm) than elevated (84 µm) or flat nevi (70 µm). In a size-matched subanalysis of 5 elevated choroidal nevi and 5 choroidal melanomas, choroidal melanomas had increased mean choroidal vessel depth (P = 0.015), deepest choroidal vessel visualized (P = 0.034), and presence of a deep choroidal vessel >155 µm (P = 0.048). CONCLUSION: Swept-source optical coherence tomography angiography may detect distinct vascular features in choroidal nevi and small choroidal melanomas.

FULL-THICKNESS MACULAR HOLE SIZE BY HYPERTRANSMISSION SIGNAL ON SPECTRAL-DOMAIN OPTICAL COHERENCE TOMOGRAPHY.

PURPOSE: To assess the full-thickness macular hole (FTMH) size using the choroidal hypertransmission signal on spectral-domain optical coherence tomography and to compare this method to the standard aperture measurement of the minimum aperture size at the level of the neurosensory retina. DESIGN: Cross-sectional study of retrospective data. METHODS: Eyes with FTMH imaged on spectral-domain optical coherence tomography were included. Two independent masked graders used the device's built-in caliper tool to measure the FTMH minimum aperture size at the level of the neurosensory retina and the size of the corresponding hypertransmission signal below the level of the retinal pigment epithelium/Bruch membrane complex. To assess the reproducibility of the hypertransmission measurement in tilted scans, two measurements were obtained and compared; the first was traced parallel to the retinal pigment epithelium (parallel hypertransmission), and the second was horizontal to the image frame (horizontal hypertransmission), both using Image J software. RESULTS: A total of 31 eyes were enrolled. The mean FTMH minimum aperture size was smaller compared with both the choroidal parallel hypertransmission and horizontal hypertransmission measurements (mean ± SD: 335.7 ± 139.5 µm, 376.7 ± 150.6 µm, 375.1 ± 150.0 µm, respectively. P < 0.001 for both comparisons). CONCLUSION: The proposed hypertransmission measurement is a feasible and reproducible alternative to assess FTMH size and could provide the basis for an automated FTMH measurement on cross-sectional spectral-domain optical coherence tomography scans, as presented in this study, or on the spectral-domain optical coherence tomography volumetric data set by using an en face projection.

Mean macular intercapillary area in eyes with diabetic macular oedema after anti-vascular endothelial growth factor therapy and its association with treatment response.

BACKGROUND: To evaluate the changes in the mean macular intercapillary area (ICA) from sequential enface optical coherence tomography angiography (OCTA) images following intravitreal anti-vascular endothelial growth factor (VEGF) therapy in initially treatment-naïve eyes with diabetic macular oedema (DME). METHODS: In this multicentre retrospective study, 6 × 6 and 3 × 3 mm customised, total retinal projection enface OCTA images were collected and processed for quantitative assessment of ICA by a customised MATLAB software. Measurements were done in concentric regions centred on the fovea-with the exclusion of foveal avascular zone (FAZ)-in 0.5 mm diameter increments as well as within the intervening rings. RESULTS: In this study, 6 × 6 mm OCTA images from 46 eyes of 29 patients, and 3 × 3 mm OCTA images from 23 eyes of 15 patients were included. There was no significant change in mean ICA after treatment in either scan size or in any measurement regions (all p > 0.05). Multivariate analysis revealed that baseline BCVA was significantly correlated with the visual outcome (p = 0.039). Additionally, after correction for age, baseline central retinal thickness (CRT), baseline BCVA, and retinopathy severity, mean ICA in the 1.5 mm circle was found to be a significant predictor of post treatment CRT, (p = 0.006). CONCLUSIONS: Absence of significant change in mean ICA after a minimum of three intravitreal anti-VEGF injections, may indicate that, in the short term, anti-VEGF injections neither impair nor improve macular perfusion in DME. Baseline BCVA was found to be a robust predictor of functional outcome, while inner mean ICA was a significant predictor for macular thickness outcomes.

Repeatability and reproducibility of vessel density measurements on optical coherence tomography angiography in diabetic retinopathy.

PURPOSE: Understanding the precision of measurements on and across optical coherence tomography angiography (OCTA) devices is critical for tracking meaningful change in disease. The purpose of this study is to investigate the repeatability and reproducibility of vessel area density and vessel skeleton density measurements from various commercial OCTA devices in diabetic eyes. METHODS: Patients were imaged three consecutive times each on three different OCTA devices. En face OCTA images of the superficial capillary plexus, deep capillary plexus, and full retinal layer were exported for analysis. Vessel area density and vessel skeleton density were calculated. The coefficient of repeatability (CoR) was calculated to assess the repeatability of these measurements, and linear mixed models were utilized to assess the reproducibility of these measurements. RESULTS: Forty-four eyes from 27 diabetic patients were imaged. Normalized CoR values ranged between 3.44 and 6.65% when calculated for vessel area density and between 1.35 and 23.39% when calculated for vessel skeleton density. When stratified by disease severity, the swept-source OCTA device consistently produced the smallest CoR values for vessel area density in the full retinal layer. Vessel area density measurements were repeatable across the two spectral-domain devices in the full retinal layer when all severities were combined, as well as in diabetic patients without retinopathy, mild nonproliferative diabetic retinopathy (NPDR), and moderate NPDR. CONCLUSION: Vessel area density measured in the full retinal layer may be a more precise measure than vessel skeleton density to follow diabetic retinopathy patients both on the same device and across devices.

Effects of enhanced depth imaging and en face averaging on optical coherence tomography angiography image quantification.

PURPOSE: To examine the effects of enhanced depth imaging (EDI) and en face averaging on global vascular measurements of optical coherence tomography angiography (OCTA) images. METHODS: All eyes were imaged with 3 mm × 3 mm fields centered at the fovea using the Carl Zeiss Cirrus 5000 spectral-domain OCTA, with and without EDI, and the Zeiss PLEX Elite 9000 swept-source OCTA. Vessel area density (VAD), vessel length (VL), and vessel diameter index (VDI) were calculated for the superficial capillary plexus (SCP) en face angiograms. For the choriocapillaris (CC), VAD and the number, total area, and average size of flow voids were calculated. These metrics were compared between SD- and SS-OCTA images, with and without en face averaging and EDI. RESULTS: Both averaging and EDI had a significant effect on quantitative metrics. EDI images trended toward a decrease in SCP VAD. In the CC, EDI decreased average flow void size. Averaging increased CC VAD while decreasing number of flow voids, total flow void area, and average flow void size. With both averaging and EDI, SD-OCTA was not able to visualize as many CC flow voids, particularly of a smaller size, compared with SS-OCTA. CONCLUSIONS: Averaging and EDI affect quantitative metrics from SCP and CC OCTA images. EDI resulted in a trend toward decreased VAD in SCP images. Averaging had a major effect on CC imaging. Even with the combination of EDI and en face averaging, SD-OCTA images do not appear to approximate SS-OCTA images in terms of quantitative metrics. This has implications for clinical and research use of SD-OCTA for retinal imaging.

MACULAR ATROPHY IN NEOVASCULAR AGE-RELATED MACULAR DEGENERATION: A Pilot Post Hoc Analysis of Patients With Pigment Epithelial Detachments.

PURPOSE: To determine optical coherence tomography signs associated with macular atrophy (MA) in eyes with neovascular age-related macular degeneration and pigment epithelial detachments treated with vascular endothelial growth factor inhibitors. METHODS: Optical coherence tomography scans from a subgroup of the pigment epithelial detachment cohort of the HARBOR study were analyzed for MA. Two groups were formed based on MA presence/absence at Month 24. Then, optical coherence tomography scans from each baseline visit were graded with standard reading center grading parameters including ellipsoid zone disruption, intraretinal cysts, subretinal fluid, and MA or nascent MA in the study and fellow eyes. RESULTS: Twenty-eight eyes from 28 patients were included in the analysis. Fourteen eyes had optical coherence tomography-based MA at Month 24 and 14 did not. Macular atrophy at Month 24 was significantly associated with 1) MA/nascent MA at baseline (P = 0.0136), 2) intraretinal cysts at baseline (P = 0.0048), and 3) collapse of pigment epithelial detachments in the study eye (P = 0.0025). Macular atrophy was not associated with ellipsoid zone disruption or subretinal fluid in the study eye at baseline. CONCLUSION: This study suggests that some optical coherence tomography findings in eyes of patients with neovascular age-related macular degeneration were present before the start of anti-vascular endothelial growth factor therapy and may predict the development of MA.

DISTINGUISHING INTRARETINAL MICROVASCULAR ABNORMALITIES FROM RETINAL NEOVASCULARIZATION USING OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY.

PURPOSE: With the increasing prevalence of diabetes, fast, noninvasive identification of proliferative diabetic retinopathy (PDR) becomes essential. This study evaluated the utility of optical coherence tomography angiography (OCTA) to characterize intraretinal microvascular abnormalities (IRMA) and retinal neovascularization (NV). METHODS: Patients with severe non-PDR or PDR were imaged with fluorescein angiography and widefield swept-source OCTA (Zeiss Plex Elite 9000; Carl Zeiss Meditec, Dublin, CA). Regions suspicious for IRMA or retinal NV were identified and the OCTA, including flow overlay on the co-registered structural optical coherence tomography, and fluorescein angiography images were graded by two masked readers. RESULTS: Ninety-six foci of irregular vasculature were analyzed, comprised of 70 IRMA and 26 retinal NV lesions from 14 eyes. Compared with fluorescein angiography, OCTA with flow overlay demonstrated specificity of 99% and sensitivity of 92% in identifying IRMA and NV. Neovascularization differed from IRMA on OCTA by demonstrating supraretinal flow breaching the internal limiting membrane and posterior hyaloid (P < 0.001). Intraretinal microvascular abnormalities were distinguished from NV by outpouching of the internal limiting membrane (P = 0.035). Vascular flow was reduced in the presence of fibrosis. CONCLUSION: Optical coherence tomography angiography, through flow overlay, has utility to image and differentiate IRMA and NV, which are key features distinguishing severe non-PDR and PDR, respectively. Noninvasive widefield OCTA may be a useful tool to diagnose high-risk diabetic retinopathy eyes.

CHANGES IN CHORIOCAPILLARIS, SATTLER, AND HALLER LAYER THICKNESSES IN CENTRAL SEROUS CHORIORETINOPATHY AFTER HALF-FLUENCE PHOTODYNAMIC THERAPY.

PURPOSE: To determinate the variation in thickness of the individual choroidal layers in patients with central serous chorioretinopathy treated with half-fluence photodynamic therapy. METHODS: Twenty-two eyes were evaluated with spectral-domain optical coherence tomography. The images were taken before photodynamic therapy, 3 months, and 6 months after the treatment. Two investigators performed these measurements: 1) choroidal thickness (CT), 2) Haller layer thickness, defined as the most external layer containing a 100-µm vessel, and 3) choriocapillaris + Sattler layer (C&S). Nine measurements were taken in the macular region. RESULTS: Choroidal thickness before photodynamic therapy was 471.8 µm ± 145.8. The Haller layer was 358.4 µm ± 122.6, and C&S was 114.3 µm ± 27.8. At 3-month follow-up, CT was 441.1 µm ± 150.7, Haller layer 348.8 µm ± 127.6, and C&S 92.4 µm ± 27.9. At 6-month follow-up, CT was 420.4 µm ± 118.4, Haller layer 331.8 µm ± 97.2, and C&S 89.5 µm ± 28.0. Using a multilevel mixed-effects linear regression, CT was found to be reduced at both 3 months (P < 0.03) and at 6 months (P < 0.001), Haller layer showed no significant reduction at 3 months (P = 0.483) or at 6 months (P = 0.055), and C&S showed reduction at 3 months (P < 0.001) and at 6 months (P < 0.001). Fellow nonaffected eyes showed no statistical variation at 3-month and 6-month follow-up. CONCLUSION: Reduction in CT in patients affected by central serous chorioretinopathy after half-fluence photodynamic therapy occurs primarily in the choriocapillaris and medium diameter vessel layers of the choroid in a short- and medium-term follow-up.

QUANTIFICATION OF RETINAL CAPILLARY NONPERFUSION IN DIABETICS USING WIDE-FIELD OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY.

PURPOSE: To combine advances in high-speed, wide-field optical coherence tomography angiography (OCTA) with image processing methods for semiautomatic quantitative analysis of capillary nonperfusion in patients with diabetic retinopathy (DR). METHODS: Sixty-eight diabetic patients (73 eyes), either without retinopathy or with different degrees of retinopathy, were prospectively recruited for volumetric swept-source OCTA imaging using 12 mm × 12 mm fields centered at the fovea. A custom, semiautomatic software algorithm was used to quantify areas of capillary nonperfusion. RESULTS: The mean percentage of nonperfused area was 0.1% (95% confidence interval: 0.0-0.4) in the eyes without DR; 2.1% (95% confidence interval: 1.2-3.7) in the nonproliferative DR eyes (mild, moderate, and severe), and 8.5% (95% confidence interval: 5.0-14.3) in the proliferative DR eyes. The percentage of nonperfused area increased in a statistically significant manner from eyes without DR, to eyes with nonproliferative DR, to eyes with proliferative DR. CONCLUSION: Capillary nonperfusion area in the posterior retina increases with increasing DR severity as measured by swept-source OCTA. Quantitative analysis of retinal nonperfusion on wide-field OCTA may be useful for early detection and monitoring of disease in patients with diabetes and DR.

SPATIAL DISTRIBUTION OF CHORIOCAPILLARIS IMPAIRMENT IN EYES WITH CHOROIDAL NEOVASCULARIZATION SECONDARY TO AGE-RELATED MACULAR DEGENERATION: A Quantitative OCT Angiography Study.

PURPOSE: To develop an optical coherence tomography angiography (OCTA)-based framework for quantitatively analyzing the spatial distribution of choriocapillaris (CC) impairment around choroidal neovascularization (CNV) secondary to age-related macular degeneration. METHODS: In a retrospective, cross-sectional study, 400-kHz swept-source OCTA images from 7 eyes of 6 patients with CNV secondary to age-related macular degeneration were quantitatively analyzed using custom software. A lesion-centered zonal OCTA analysis technique-which portioned the field-of-view into zones relative to CNV boundaries-was developed to quantify the spatial dependence of CC flow deficits. RESULTS: Quantitative, lesion-centered zonal analysis of CC OCTA images revealed highest flow-deficit percentages near CNV boundaries, decreasing in zones farther from the boundaries. Optical coherence tomography angiography using shorter (1.5 ms) interscan times revealed more severe flow deficits than OCTA using longer (3.0 ms) interscan times; however, spatial trends were similar for both interscan times. A detailed description of the OCTA processing steps and parameters was provided so as to elucidate their influence on quantitative measurements. CONCLUSION: Impairment of the CC, assessed by flow-deficit percentages, was most prominent closest to CNV boundaries. The lesion-centered zonal analysis technique enabled quantitative CC measurements relative to focal lesions. Understanding how processing steps, imaging/processing parameters, and artifacts can affect quantitative CC measurements is important for longitudinal, OCTA-based studies of disease progression, and treatment response.

VISUALIZATION OF CHOROIDAL NEOVASCULARIZATION USING TWO COMMERCIALLY AVAILABLE SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY DEVICES.

PURPOSE: To compare the sensitivity of detection and the measured size of choroidal neovascularization (CNV) on two commercially available spectral domain optical coherence tomography angiography (OCTA) devices, the Optovue RTVue XR Avanti with AngioVue and the Zeiss Cirrus HD-OCT with AngioPlex. METHODS: Patients with CNV lesions were imaged consecutively on both OCTA devices on the same day of their visit. 3 × 3 mm and 6 × 6 mm scans centered at the fovea were obtained. Two independent masked readers evaluated the OCTA images for CNV identification and its area measurements. RESULTS: No significant differences were observed between the 2 OCTA devices in CNV area measurements on their 3 × 3 mm and 6 × 6 mm scans. However, there was suboptimal performance of their automated segmentation algorithms as compared to manually adjusted segmentation for visualizing CNV lesions. CONCLUSION: There was no significant difference in the size of the CNV lesion as measured on either commercially available spectral domain OCTA device. Both devices were comparable in their detection of CNV lesions on manual adjustment of segmentation lines. However, their automated segmentation algorithms need improvement to allow for accurate measurement of CNV lesions for routine clinical application.

Optical coherence tomography angiography analysis of macular vessel density before and after anti-VEGF therapy in eyes with diabetic retinopathy.

PURPOSE: To evaluate changes in macular vessel density following intravitreal anti-VEGF injection in patients with diabetic macular edema (DME) and proliferative diabetic retinopathy (PDR). METHODS: In this retrospective case series, optical coherence tomography angiography (OCTA) images from 55 eyes of 35 patients with either DME (46 eyes) or PDR (9 eyes) were included. Macular capillary vessel density at the level of the superficial retinal capillary plexus (SCP), deep retinal capillary plexus (DCP) and total retinal capillary plexus (TCP) before and after anti-VEGF treatment was calculated. Longitudinal changes in vessel density following serial anti-VEGF treatment were analyzed in a subset of eyes. RESULTS: Vessel density in the SCP, DCP or TCP was not found to be significantly different after one, two or three intravitreal injections (p > 0.05 for all time points). Subgroup analysis revealed no significant change in the DME and PDR subgroups (all p > 0.05). Multivariate analysis revealed no effect of type of injected anti-VEGF agent or presence of previous treatment on VD measurements (all p > 0.05). There was no correlation between the anatomic response of DME to treatment and VD measurements. CONCLUSIONS: In this study, macular vessel density remained statistically unchanged following up to three intravitreal injections of any anti-VEGF agent. This indicates that there may not be an early effect of anti-VEGF treatment on macular vessel density and its effect on macular perfusion may not be a direct change in microvascular flow.

OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY TO DETECT MACULAR CAPILLARY ISCHEMIA IN PATIENTS WITH INNER RETINAL CHANGES AFTER RESOLVED DIABETIC MACULAR EDEMA.

PURPOSE: To compare foveal vascular anatomy between patients with and without disorganization of retinal inner layers (DRILs) after resolved diabetic macular edema using optical coherence tomography angiography (OCTA). METHODS: Twenty-four eyes of 21 age- and sex-matched patients with resolved diabetic macular edema were included in this retrospective, cross-sectional study. All eyes were imaged with enhanced high-definition line or cross-line structural B scans and 3 × 3-mm OCTA scans. Optical coherence tomography B scans were analyzed for the presence of DRIL, and based on this, eyes were classified as either DRIL present or DRIL absent. The foveal avascular zone area on OCTA was compared between patients with and without DRIL. The foveal avascular zone area was correlated with visual acuity. RESULTS: Nine eyes with DRIL and resolved diabetic macular edema were compared with 15 control eyes without DRIL and resolved diabetic macular edema. Area of ischemia on OCTA scans corresponded to the area of DRIL as determined on OCT B scans. The foveal avascular zone area in full retina as well as superficial and deep retinal plexuses OCTA slabs were significantly larger in patients with DRIL as compared to those without DRIL (P = 0.005, P < 0.001, and P = 0.004, respectively). The larger foveal avascular zone in full retinal segmentation (r = 0.72, P = 0.03) and superficial plexus (r = 0.74, P = 0.02) were positively correlated with lower visual acuity. CONCLUSION: Optical coherence tomography angiography can visualize retinal ischemia in patients with and without DRIL. Correspondence of impaired blood flow with DRIL suggests that retinal ischemia and loss of normal vasculature contributes to DRIL.

ULTRAHIGH SPEED SWEPT SOURCE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY OF RETINAL AND CHORIOCAPILLARIS ALTERATIONS IN DIABETIC PATIENTS WITH AND WITHOUT RETINOPATHY.

PURPOSE: To investigate the utility of ultrahigh speed, swept source optical coherence tomography angiography in visualizing retinal microvascular and choriocapillaris (CC) changes in diabetic patients. METHODS: The study was prospective and cross-sectional. A 1,050 nm wavelength, 400 kHz A-scan rate swept source optical coherence tomography prototype was used to perform volumetric optical coherence tomography angiography of the retinal and CC vasculatures in diabetic patients and normal subjects. Sixty-three eyes from 32 normal subjects, 9 eyes from 7 patients with proliferative diabetic retinopathy, 29 eyes from 16 patients with nonproliferative diabetic retinopathy, and 51 eyes from 28 diabetic patients without retinopathy were imaged. RESULTS: Retinal and CC microvascular abnormalities were observed in all stages of diabetic retinopathy. In nonproliferative diabetic retinopathy and proliferative diabetic retinopathy, optical coherence tomography angiography visualized a variety of vascular abnormalities, including clustered capillaries, dilated capillary segments, tortuous capillaries, regions of capillary dropout, reduced capillary density, abnormal capillary loops, and foveal avascular zone enlargement. In proliferative diabetic retinopathy, retinal neovascularization above the inner limiting membrane was visualized. Regions of CC flow impairment in patients with proliferative diabetic retinopathy and nonproliferative diabetic retinopathy were also observed. In 18 of the 51 of eyes from diabetic patients without retinopathy, retinal mircrovascular abnormalities were observed and CC flow impairment was found in 24 of the 51 diabetic eyes without retinopathy. CONCLUSION: The ability of optical coherence tomography angiography to visualize retinal and CC microvascular abnormalities suggests it may be a useful tool for understanding pathogenesis, evaluating treatment response, and earlier detection of vascular abnormalities in patients with diabetes.

ANALYSIS OF AGE-RELATED CHOROIDAL LAYERS THINNING IN HEALTHY EYES USING SWEPT-SOURCE OPTICAL COHERENCE TOMOGRAPHY.

PURPOSE: To study the changes in the choroidal layers thickness with age in a healthy population using swept-source optical coherence tomography. METHODS: Retrospective data analysis of a subgroup of eyes from a previous single-center, prospective, cross-sectional, noninterventional study. One hundred and sixty-nine healthy eyes were evaluated using swept-source optical coherence tomography. Inclusion criteria were best-corrected visual acuity between 20/20 and 20/25, spherical equivalent between ±3 diopters, and no systemic or ocular diseases. Two independent investigators determined the macular horizontal choroidal thickness (CT) and the Haller's layer thickness across a 9 mm line centered at the fovea. Subjects were divided into five age groups. RESULTS: Mean subfoveal choroidal thickness was 305.76 ± 80.59 µm (95% confidence interval: 294.85-319.33). Mean subfoveal thickness for Haller's layer was 215.47 ± 67.70 µm (95% confidence interval: 207.30-227.86) and mean subfoveal thickness for choriocapillaris plus Sattler's layer was 87.31 ± 40.40 µm (95% confidence interval: 83.38-95.65). No significant differences were found due to gender. Choroidal thickness profile was similar between groups with choroidal thickness and Haller's layer thickness decreasing with age (P = 0.002). CONCLUSION: Choroidal and Haller's layer thickness profiles are similar between different age groups. Age-related choroidal thinning is mostly at the expense of Haller's layer.

Optical Coherence Tomography Angiography in Nonarteritic Anterior Ischemic Optic Neuropathy.

BACKGROUND: Optical coherence tomography angiography (OCTA) has demonstrated good utility in qualitative analysis of retinal and choroidal vasculature and therefore may be relevant in the diagnostic and treatment efforts surrounding nonarteritic anterior ischemic optic neuropathy (NAION). METHODS: Retrospective, cross-sectional study of 10 eyes of 9 patients with a previous or new diagnosis of NAION that received imaging with OCTA between November 2015 and February 2016. Two independent readers qualitatively analyzed the retinal peripapillary capillaries (RPC) and peripapillary choriocapillaris (PCC) for flow impairment. Findings were compared with automated visual field and structural optical coherence tomography (OCT) studies. RESULTS: Flow impairment seen on OCTA in the RPC corresponded to structural OCT deficits of the retinal nerve fiber layer (RNFL) and ganglion cell layer complex (GCC) in 80% and 100% of eyes, respectively, and to automated visual field deficits in 90% of eyes. Flow impairment seen on OCTA in the PCC corresponded to structural OCT deficits of the RNFL and GCC in 70% and 80% of eyes, respectively, and to visual field deficits in 60%-80% of eyes. CONCLUSIONS: OCTA can noninvasively visualize microvascular flow impairment in patients with NAION.

CORRELATION OF SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY AND CLINICAL ACTIVITY IN NEOVASCULAR AGE-RELATED MACULAR DEGENERATION.

PURPOSE: To characterize the features of choroidal neovascularization (CNV) in neovascular age-related macular degeneration with spectral domain optical coherence tomography angiography (OCTA) and to determine whether OCTA can be used to determine clinical activity of CNV. METHODS: Observational, retrospective, consecutive case series. RESULTS: Optical coherence tomography angiography revealed CNV in 28 eyes (62.2%) while 17 eyes (37.8%) did not demonstrate CNV vessels. Choroidal neovascularization was classified as well circumscribed in 12 eyes (42.8%) and poorly circumscribed in 16 eyes (57.2%). Twenty-two eyes with a CNV on OCTA were clinically active, whereas six eyes with visible CNV on OCTA were clinically inactive. Of the 17 eyes that did not have evidence of CNV on OCTA imaging, 14 were clinically inactive and 3 were clinically active. Presence of CNV on OCTA correlated with clinical activity and absence of CNV correlated with inactivity (P < 0.0001). CONCLUSION: Optical coherence tomography angiography is a noninvasive imaging technique that can be used to visualize blood flow comprising CNV. Optical coherence tomography angiography detects CNV vessels in some albeit not all eyes with neovascular age-related macular degeneration. Although the presence or absence of CNV vessels on OCTA highly correlated with clinical activity of CNV, the morphologic appearance of CNV on OCTA did not have significant correlation with clinical activity.

SWEPT-SOURCE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY REVEALS CHORIOCAPILLARIS ALTERATIONS IN EYES WITH NASCENT GEOGRAPHIC ATROPHY AND DRUSEN-ASSOCIATED GEOGRAPHIC ATROPHY.

PURPOSE: To investigate choriocapillaris (CC) alteration in patients with nascent geographic atrophy (nGA) and/or drusen-associated geographic atrophy (DAGA) using swept-source optical coherence tomography angiography (OCTA). METHODS: A 1,050-nm wavelength, 400 kHz A-scan rate swept-source optical coherence tomography prototype was used to perform volumetric swept-source optical coherence tomography angiography over 6 mm × 6 mm fields of view in patients with nGA and/or DAGA. The resulting optical coherence tomography (OCT) and OCTA data were analyzed using a combination of en face and cross-sectional techniques. Variable interscan time analysis (VISTA) was used to differentiate CC flow impairment from complete CC atrophy. RESULTS: A total of 7 eyes from 6 patients (mean age: 73.8 ± 5.7 years) were scanned. Seven areas of nGA and three areas of DAGA were identified. Analysis of cross-sectional OCT and OCTA images identified focal alterations of the CC underlying all seven areas of nGA and all three areas of DAGA. En face OCTA analysis of the CC revealed diffuse CC alterations in all eyes. Variable interscan time analysis processing suggested that the observed CC flow alterations predominantly corresponded to flow impairment rather than complete CC atrophy. CONCLUSION: The OCTA imaging of the CC revealed focal CC flow impairment associated with areas of nGA and DAGA, as well as diffuse CC flow impairment throughout the imaged field. En face OCT analysis should prove useful for understanding the pathogenesis of nGA and DAGA and for identifying the formation of nGA and DAGA as endpoints in therapeutic trials.