Comparison between Spectral-Domain and Swept-Source OCT Angiography for the Measurement of Persistent Hypertransmission Defects in Age-Related Macular Degeneration.

Purpose: Spectral-domain OCT angiography (SD-OCTA) scans were tested in an algorithm developed for use with swept-source OCT angiography (SS-OCTA) scans to determine if SD-OCTA scans yielded similar results for the detection and measurement of persistent choroidal hypertransmission defects (hyperTDs). Design: Retrospective study. Participants: Forty pairs of scans from 32 patients with late-stage nonexudative age-related macular degeneration (AMD). Methods: Patients underwent both SD-OCTA and SS-OCTA imaging at the same visit using the 6 × 6 mm OCTA scan patterns. Using a semiautomatic algorithm that helped with outlining the hyperTDs, 2 graders independently validated persistent hyperTDs, which are defined as having a greatest linear dimension ≥250 µm on the en face images generated using a slab extending from 64 to 400 µm beneath Bruch's membrane. The number of lesions and square root (sqrt) total area of the hyperTDs were obtained from the algorithm using each imaging method. Main Outcome Measures: The mean sqrt area measurements and the number of hyperTDs were compared. Results: The number of lesions and sqrt total area of the hyperTDs were highly concordant between the 2 instruments (rc = 0.969 and rc = 0.999, respectively). The mean number of hyperTDs was 4.3 ± 3.1 for SD-OCTA scans and 4.5 ± 3.3 for SS-OCTA scans (P = 0.06). The mean sqrt total area measurements were 1.16 ± 0.64 mm for the SD-OCTA scans and 1.17 ± 0.65 mm for the SS-OCTA scans (P < 0.001). Because of the small standard error of the differences, the mean difference between the scans was statistically significant but not clinically significant. Conclusions: Spectral-domain OCTA scans provide similar results to SS-OCTA scans when used to obtain the number and area measurements of persistent hyperTDs through a semiautomated algorithm previously developed for SS-OCTA. This facilitates the detection of atrophy with a more widely available scan pattern and the longitudinal study of early to late-stage AMD. Financial Disclosures: Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Evaluating the persistence of large choroidal hypertransmission defects using SS-OCT imaging.

In age-related macular degeneration (AMD), large choroidal hypertransmission defects (hyperTDs) are identified on en face optical coherence tomography (OCT) images as bright lesions measuring at least 250 µm in greatest linear dimension (GLD). These choroidal hyperTDs arise from focal attenuation or loss of the retinal pigment epithelium (RPE). We previously reported that once large hyperTDs formed, they were likely to persist compared with smaller lesions that were more likely to be transient. Due to their relative persistence, these large persistent choroidal hyperTDs are a point-of-no-return in the progression of intermediate AMD to the late stage of atrophic AMD. Moreover, the onset of these large choroidal hyperTDs can serve as a clinical trial endpoint when studying therapies that might slow disease progression from intermediate AMD to late atrophic AMD. To confirm the persistence of these large choroidal hyperTDs, we studied an independent dataset of AMD eyes enrolled in an ongoing prospective swept-source OCT (SS-OCT) natural history study to determine their overall persistence. We identified a total of 202 eyes with large choroidal hyperTDs containing 1725 hyperTDs followed for an average of 46.6 months. Of the 1725 large hyperTDs, we found that 1718 (99.6%) persisted while only 7 hyperTDs (0.4%) were non-persistent. Of the 7 non-persistent large hyperTDs in 6 eyes, their average GLD at baseline was 385 µm. Of the large hyperTDs ranging in size between 250 and 300 µm when first detected, only one was not persistent with a baseline GLD of 283 µm. In 6 of the non-persistent hyperTDs, the loss of a detectable large hyperTD was due to the accumulation of hyperreflective material along the retinal pigment epithelium (RPE) and in the retina over the area where the hyperTD was located. This hyperreflective material is thought to represent the migration and aggregation of RPE cells into this focal region where the choroidal hyperTD arose due to attenuated or lost RPE.

Quantitative assessment of choroidal parameters in type 1 macular neovascularization linked to central serous chorioretinopathy and neovascular age-related macular degeneration.

OBJECTIVE: To use ultra-widefield swept-source optical coherence tomography angiography (UWF SS-OCTA) to evaluate the choroidal features of neovascular age-related macular degeneration (nAMD) and type 1 macular neovascularization (MNV) attributable to central serous chorioretinopathy (CSC). METHOD: A cross-sectional research was carried out to examine patients with type 1 MNV due to CSC (50 eyes) and nAMD (98 eyes) utilizing UWF SS-OCTA examinations. The scan procedure covered a vertical 20 mm × horizontal 24 mm region with 9 subfields. A typical set of 68 healthy eyes was used for comparison. The effects of different diagnoses on choroidal parameters were assessed using covariance tests, using gender and age as variables. RESULTS: The research showed that all choroidal characteristics were age-related (all p < 0.05). The calculated marginal averages of choroidal thickness (ChT) and choroidal volume (CV) in the central area were substantially lower in the nAMD group than in the CSC group and the normal group after age differences were taken into account (all p < 0.05). In both the superotemporal and temporal areas, the CSC group had a greater choroidal vascular index (CVI) compared to the nAMD group (p < 0.05). Additionally, the CSC group had a greater temporal area choriocapillaris density (CCD) than the nAMD group (p < 0.05). CONCLUSION: At the choroidal level, type 1 MNV due to CSC and nAMD may be distinguished by UWF SS-OCTA. Compared to the nAMD affected eyes, the CSC affected eyes had increased ChT, CV, CVI, and CCD in several areas. The two diseases could be distinguished based on ChT and CV.

Uveal colobomas with pseudo-duplication of the optic disc in both eyes: imaging by ultra-widefield swept-source optical coherence tomography angiography: a case report.

BACKGROUND: Duplication of the optic disc is a rare phenomenon. Differentiating between true duplication and pseudo-duplication requires a comprehensive set of diagnostic procedures. Advancements in imaging provide new insights into this condition. CASE PRESENTATION: This report details a unique case involving an 8-year-old Han Chinese girl diagnosed with uveal colobomas and pseudo-duplication of the optic disc in both eyes. The extensive multimodal examination included assessments of vision, fundus examination, fundus photography, B-scan ultrasonography, ultra-widefield swept-source optical coherence tomography angiography, fundus fluorescein angiography, fundus autofluorescence, and magnetic resonance imaging. CONCLUSION: Ultra-widefield swept-source optical coherence tomography angiography proves to be a vital tool for examining and monitoring uveal colobomas with pseudo-duplication of the optic disc.

Wide-field swept-source optical coherence tomography angiography (SS-OCTA) in the assessment of retinal vessel density and thickness in 4-to 16-year-old myopic children.

PURPOSE: To analyze the characteristics of macular retinal vessel density and thickness in children with myopia. METHODS: A cross-sectional study was conducted. A total of 228 children aged 4-16 years who visited the Ineye Hospital of Chengdu University of Traditional Chinese Medicine from September 2022 to November 2023 were included. Those with -0.5D < spherical equivalent (SE) < +2.0D were included in the non-myopia group (150 eyes), those with -3.0D < SE ≤ -0.5D were included in the low myopia group (246 eyes), and those with SE ≤ -3.0D were included in the moderate-to-high myopia group (60 eyes). All subjects underwent cycloplegic refraction, IOLmaster500, and Wide-field SS-OCTA (to exclude some peripheral retinal degeneration). Multiple linear regression analysis was used to analyze the correlation between macular ETDRS subfield of full retinal thickness (FRT), outer, inner retinal thickness (ORT, IRT), retinal vessel density (VD), deep and superficial retinal vessel density (DVD, SVD), and SE, axial length (AL). RESULTS: There were statistically significant differences (P < 0.05) in FRT in the central fovea (1 mm diameter)and perifovea (Diameter 3 to 6 mm) among the non-myopia group, low myopia group, and moderate-to-high myopia group. The three groups also showed statistically significant differences (P < 0.05) in VD in the central fovea and parafovea with a diameter of 1 to 3 mm (except the lower part). In multiple linear regression analysis adjusted for gender and age, SE and AL were found to be correlated with FRT in all ETDRS regions (except the central fovea) (P < 0.01), and SE and AL were correlated with IRT in the central fovea and perifovea, respectively (ß range -2.302 to 1.652; P < 0.05). SE and AL were also correlated with ORT in the parafovea and perifovea, respectively (ß range -4.371 to -2.344; P < 0.05). AL was negatively correlated with VD in the central fovea and parafovea (except the inferior region) (P < 0.05), as well as with DVD in all ETDRS regions (ß range -1.314 to -1.031; P < 0.05). AL was only negatively correlated with SVD in the parafoveal nasal region (ß = -0.633, P < 0.05). Additionally, the correlation between AL and DVD, ORT was higher than that with SVD, IRT. CONCLUSION: The more severe the myopia, the longer the AL, the thinner the FRT in the perifovea, and the lower the VD in both the fovea and parafovea in children. In addition, DVD and ORT were more significantly correlated with AL, suggesting that they may be more closely related to the growth of AL.

Case report: Intraretinal hyperflow microinfiltration lesions on swept-source optical coherence tomography angiography as a potential biomarker of primary vitreoretinal lymphoma.

Primary vitreoretinal lymphoma (PVRL) is often associated with central nervous system involvement, contributing to a heightened mortality rate, thus imaging features that are characteristic enough to be potential biomarkers of PVRL are important, either in diagnosis or in assessment of disease activity. This report details the case of a 68-year-old male who presented with blurred vision in both eyes persisting for 2 months. Fundus examination demonstrated vitreous opacity and multiple subretinal yellow nodular lesions of varying sizes in the peripheral fundus of both eyes. Multiple vertical hyperreflective lesions in the neural retina of posterior pole, indistinct outer retina borders in the fovea, and hyperreflective lesions in the sub-retinal pigment epithelium (RPE) space of the peripheral retina were demonstrated on swept-source optical coherence tomography (SS-OCT) of the left eye. Hyperflow signals corresponding to the vertical hyperreflective lesions were detected on swept-source optical coherence tomography angiography (SS-OCTA) images of retinal deep capillary plexus (DCP) layer. Notably, the hyperflow signals, precisely located around retinal vessels from the nerve fiber layer to the outer plexiform layer, were postulated to stem from the dilation of infiltrated retinal vessels. Vitreous pathological results of the left eye confirmed the diagnosis of PVRL. Treatments with intravitreal methotrexate injections led to a marked improvement of best-corrected visual acuity (BCVA) and regression of the hyperflow microinfiltration lesions demonstrated on SS-OCTA. In conclusion, SS-OCTA effectively delineated the vertical hyperreflective lesions and corresponding hyperflow signals in the posterior pole macular region of a patient with PVRL. These lesions significantly diminished following intravitreal methotrexate injections. We speculated that the specific hyperflow signals on SS-OCTA could act as a potential biomarker of PVRL, and SS-OCTA holds promise in facilitating early diagnosis and monitoring therapeutic responses in PVRL cases.

Observation of structural and vascular features of retina and choroid in myopia using ultra-widefield SS-OCTA.

BACKGROUND: To find the relationship between the changes of retinal and choriodal structure/ vascular densities (VD) and the myopia progress. METHODS: 126 eyes of 126 age-matched young participants were divided into three groups: Emmetropia and Low Myopia (EaLM) (33 eyes), Moderate Myopia (MM) (39 eyes), and High Myopia (HM) (54 eyes). Fundus images measuring 12 × 12 mm were captured using ultra-widefield swept-source optical coherence tomography angiography (SS-OCTA). Each image was uniformly divided into nine regions: supra-temporal (ST), temporal (T), infra-temporal (IT), superior (S), central macular area (C), inferior (I), supra-nasal (SN), nasal (N), and infra-nasal (IN). Various structural parameters, including inner retina thickness (IRT), outer retina thickness (ORT), and choroid thickness (CT), were assessed, and the VD of the superficial capillary plexus (SCP), deep capillary plexus (DCP), choriocapillaries (CC), and choroid vessels (ChdV) were quantified. RESULTS: CT in upper fundus exhibited a significant reduction from EaLM to MM. Additionally, ORT (ST, S. SN, C, N, IT, I, IN), CT (ST, S, SN, T, C, N, IT, I, IN) and VDs of SCP (ST, S, C, I, IN), DCP (ST, S, T, C, I) and ChdV (T, N, I, IN) were statistically diminished in EaLM compared to HM. Furthermore, IRT (N), ORT (N, IN), CT (S, SN, T, C, IT, I) and VDs of SCP (I, IN) and DCP (I) exhibited significant decreases as MM progressed towards HM. Intriguingly, there was a notable increase in the VD of CC (ST, S, T, C, N) as myopia progressed from MM to HM. CONCLUSION: Significant changes in retinal and choroid structure and vascular density occur as moderate myopia advances to high myopia. Efforts to curb myopia progression to this stage are essential, as the failure to do so may lead to the development of corresponding retinopathy.

Quantitative assessment of choroidal parameters and retinal thickness in central serous chorioretinopathy using ultra-widefield swept-source optical coherence tomography: a cross-sectional study.

OBJECTIVE: In this study, we used ultra-wide field swept-source optical coherence tomography angiography (UWF SS-OCTA) to assess changes in retinal thickness (RT) and choroidal parameters in individuals who had received a diagnosis of central serous chorioretinopathy (CSC). METHODS: The study encompassed the evaluation of 59 eyes from 47 patients with a diagnosis of CSC, alongside 33 fellow eyes and 31 eyes from healthy individuals (controls). The parameters assessed included RT, choroidal thickness (CT), choriocapillaris density, vascular density of the large choroidal vessel layer, three-dimensional choroidal vascularity index (3D-CVI), choroidal vessel volume per unit area (mCVV/a), and choroidal stroma volume per unit area (mCSV/a). RESULTS: Metrics including mCVV/a, mCSV/a, 3D-CVI, CT, and RT exhibited significantly elevated values in the eyes affected by CSC compared to those of the control group across nine subfields. Moreover, a substantial number of the subfields in both CSC-affected and fellow eyes exhibited increased values for mCVV/a, mCSV/a, 3D-CVI, CT, and RT when compared with the control group. Additionally, acute and chronic CSC subfields demonstrated significantly elevated values for mCVV/a, mCSV/a, 3D-CVI, CT, and RT in comparison to healthy control eyes. Notably, specific subfields associated with complex and atypical forms of CSC revealed higher metrics compared to those of the control group. CONCLUSION: In conclusion, the UWF SS-OCTA proved to be a valuable tool for exploring the anatomical etiology and clinical classification and diagnosis of CSC.

Assessment of the effects of myopic and hyperopic anisometropia on choroidal vascular structure in children using SS-OCTA.

OBJECTIVE: To compare large- and medium-sized choroidal vascularity and the choriocapillaris (CC) flow area in children with different refractive errors using swept-source optical coherence tomography angiography (SS-OCTA). METHODS: Forty-two anisometropic children were enrolled and divided into hyperopic anisometropia (HA) and myopic anisometropia (MA) groups. SS-OCTA was performed to analyse choroidal vascularity. Mean choroidal thickness (CT), choroidal vascularity volume (CVV), choroidal vascularity index (CVI) and CC flow area were compared between the two eyes. The inter-ocular differences between the two groups were also determined. RESULTS: Mean CT and CVV were highest in eyes with shorter axial lengths in both refractive groups, and the difference between the two eyes was positively correlated with the difference in axial length at the foveal region. Significant differences in the CVI in the MA group were only found in the parafoveal region. Inter-ocular differences in the CC were significantly reduced in eyes with longer axial lengths in the foveal and parafoveal regions of the HA and MA groups, respectively. Comparing inter-ocular differences, CC was significantly greater in the parafoveal region of the MA group than the HA group. CONCLUSIONS: All layers of choroidal vasculature were thinner in eyes with longer axial lengths in all groups. The inter-ocular CC difference was greater in the MA than in the HA group, with similar differences in axial length. This suggests that both medium-to-large choroidal vascular and choroidal capillaries may play a role in myopia development.

Effect of mydriasis on macular and peripapillary metrics in swept-source optical coherence tomography angiography.

Introduction: The study aimed to evaluate the effect of mydriasis on macular and peripapillary metrics with swept-source optical coherence tomography angiography (SS-OCTA) in healthy subjects. Methods: Thirty-five healthy subjects were included. The macular region was scanned by the 3×3mm mode and 6×6mm mode, and the peripapillary region was scanned by the 4.5×4.5mm mode on both eyes with SS-OCTA before and after mydriasis. Macular and peripapillary metrics, including retinal vessel density (VD) and fundus thickness were measured by the built-in program. Data of the right eye were analyzed. Results: The signal strength of the scans was comparable before and after mydriasis (all P>0.05). There were no significant differences in foveal avascular zone (FAZ) parameters and retinal VD of most sectors in both macular and peripapillary areas (all P>0.05). Choroidal thickness was decreased, outer and whole retinal thickness was increased in most of the macular sectors after mydriasis (all P<0.05). Choroidal thickness was decreased in all the peripapillary sectors, but whole retinal thickness and GCC thickness were increased in some peripapillary sectors after mydriasis (all P<0.05). Conclusions: FAZ parameters and retinal VD in the most macular and peripapillary regions are not affected by mydriasis. The thickness of the choroid is decreased after mydriasis, while the thickness of retinal layers in some sectors may be increased after mydriasis.

Spectral-Domain and Swept-Source OCT Angiographic Scans Yield Similar Drusen Measurements When Processed with the Same Algorithm.

Purpose: An algorithm developed to obtain drusen area and volume measurements using swept-source OCT angiography (SS-OCTA) scans was tested on spectral-domain OCT angiography (SD-OCTA) scans. Design: Retrospective study. Participants: Forty pairs of scans from 27 eyes with intermediate age-related macular degeneration and drusen. Methods: Patients underwent both SD-OCTA and SS-OCTA imaging at the same visit using the 6 mm × 6 mm OCTA scan patterns. Using the same algorithm, we obtained drusen area and volume measurements within both 3 mm and 5 mm fovea-centered circles. Paired 2-sample t-tests were performed along with Pearson's correlation tests. Main Outcome Measures: Mean square root (sqrt) drusen area and cube root (cbrt) drusen volume within the 3 mm and 5 mm fovea-centered circles. Results: Mean sqrt drusen area values from SD-OCTA and SS-OCTA scans were 1.57 (standard deviation [SD] 0.57) mm and 1.49 (SD 0.58) mm in the 3 mm circle and 1.88 (SD 0.59) mm and 1.76 (SD 0.58) mm in the 5 mm circle, respectively. Mean cbrt drusen volume measurements were 0.54 (SD 0.19) mm and 0.51 (SD 0.20) mm in the 3 mm circle, and 0.60 (SD 0.17) mm and 0.57 (SD 0.17) mm in the 5 mm circle. Small differences in area and volume measurements were found (all P < 0.001); however, the correlations between the instruments were strong (all coefficients > 0.97; all P < 0.001). Conclusions: An algorithm originally developed for SS-OCTA scans performs well when used to obtain drusen volume and area measurements from SD-OCTA scans; thus, a separate SD-OCT structural scan is unnecessary to obtain measurements of drusen. Financial Disclosures: Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Quantitative evaluation of choroidal and retinal microvasculature post-alcohol consumption: A pilot study.

PURPOSE: The aim of this study was to assess the impact of acute, heavy alcohol consumption on the ocular microvasculature, providing insight into the largely unexplored response of microvascular structures to excessive drinking. METHODS: Healthy volunteers in this prospective pilot study were tasked with consuming spirits, wine, and water at different times. Alcohol intake was measured according to body weight (g/kg). The ocular microvascular parameters primarily including choroidal volume (CV) and choroidal vessel volume (CVV) reflecting arteriolovenularity, and choroidal capillary density (CCD) reflecting capillary, were evaluated using swept-source optical coherence tomography angiography at baseline and 0.5-, 1-, 2-, and 3-hour post-consumption. RESULTS: A total of 34 eyes underwent 170 successful examinations in this study. After consuming spirits or wine, we observed significant decreases in CV and CVV values (all P < 0.01 for 0.5-, 1-, 2-, and 3-hour post-consumption), along with significant increase in CCD (P < 0.05 at 0.5-, 1-, 2-hour post-spirits consumption and 1-hour post-wine consumption). The most pronounced changes occurred 1-hour after spirits or wine consumption (all P < 0.001 in both univariate and multivariate model). However, post-consumption changes in the ocular microvasculature showed no significant differences between spirits and wine (P > 0.05). Additionally, no significant differences were observed in any parameters after water intake (all P > 0.05). CONCLUSIONS: Excessive alcohol consumption leads to ocular arteriolovenular vasoconstriction and capillary vasodilation, most evident 1-hour post-consumption of spirits and wine. Our research provides insight into alcohol's immediate ocular microvascular effects, hinting at systemic microvascular effects.

Three-Year Follow-Up Detecting Choroidal Neovascularization with Swept Source Optical Coherence Tomography Angiography (SS-OCTA) after Successful Half-Fluence Photodynamic Therapy for Chronic Central Serous Chorioretinopathy.

Purpose: To assess the clinical course, structural changes, and choroidal neovascularization detection by SS-OCTA in long-standing and resolved patients with chronic central serous chorioretinopathy (cCSC) after successful half-fluence photodynamic therapy (hf-PDT) treatment. Methods: Twenty-four eyes presenting with cCSC were examined with SS-OCTA and were classified as choroidal neovascular (CNV) or non-choroidal neovascular (non-CNV) cCSC depending on the vascular pattern detected by SS-OCTA after one, two, and three years after hf-PDT. Two groups were compared based on the following clinical findings: demographic characteristics, time of clinical signs, best corrected visual acuity (BCVA), central retinal thickness (CRT), central choroidal thickness (CFT), subretinal fluid (SRF), flat, irregular pigment epithelial detachment (FIPED), and features of fluorescein angiography (FA) and vascular pattern by SS-OCTA. Results: All patients showed resolved cCSC during follow-up after hf-PDT. A total of 5 of 24 (20.8%) eyes showed a neovascular pattern by SS-OCTA. No differences between BCVA, CRT, SRF, FIPED, or FA features were found between both groups (p > 0.05). However, CFT and older age were associated with a neovascular pattern by SS-OCTA (p < 0.05) in follow-up. No signs of neovascular activity were detected by SS-OCT during follow-up in CNV cCSC patients, and no antiVEGF treatment was required for three-year follow-ups. Conclusions: Despite patients with cCSC showing a favorable clinical response after hf-PDT, lower foveal thickness and older age were associated with CNV patterns by SS-OCTA during follow-up.

Quantitative Wide-Field Swept-Source Optical Coherence Tomography Angiography and Visual Outcomes in RAO.

Purpose: Retinal artery occlusion (RAO) is an ophthalmic emergency that can lead to poor visual outcomes and is associated with an increased risk of stroke and cardiovascular events. Wide-field swept-source OCT-A (WF SS-OCTA) can provide quick and non-invasive angiographic information with a wide field of view. Here, we looked for associations between OCT-A vascular imaging metrics and vision in RAO patients. Methods: Patients with diagnoses of central (CRAO) or branched retinal artery occlusion (BRAO) were included. 6mm × 6mm Angio and 15mm × 15mm AngioPlex Montage OCT-A images were obtained for both eyes in each patient using Zeiss Plex Elite 9000 WF SS-OCTA device. Each 6mm × 6mm image was divided into nine Early Treatment Diabetic Retinopathy Study (ETDRS) subfields. Non-perfusion area (NPA) was manually measured using 15mm × 15mm images. A linear regression model was utilized to identify correlation between imaging metrics and vision. P-values less than 0.05 were considered as statistically significant. Results: Twenty-five subjects were included. For RAO eyes, there was a statistically significant inverse correlation between retinal thickness as well as superficial capillary plexus (SCP) vessel density (VD) and vision. An inverse correlation was found between deep capillary plexus (DCP) VD and vision without statistical significance. There was a positive correlation between choroidal thickness as well as choroidal volume and vision without statistical significance. No significant correlation was found between the metrics and vision in contralateral eyes. For NPA and vision, no significant correlation was identified. Conclusion: This is the first study to investigate the utility of WF SS-OCTA in RAO and to demonstrate correlations between retinal vascular imaging metrics and visual outcomes. The results of this study provide a basis to understand the structural changes involved in vision in RAO and may guide management of RAO and prevention of cerebral stroke and cardiovascular accidents.

Optical coherence tomography angiography biomarkers in a bi-monthly maintenance dosing aflibercept in patients with neovascular age-related macular degeneration.

PURPOSE: To evaluate the correlations between swept-source optical coherence tomography angiography (SS-OCTA) parameters and clinical outcomes in eyes with neovascular age-related macular degeneration (nAMD) administered a bimonthly intravitreal aflibercept regimen. METHODS: This prospective, single-arm, interventional study enrolled 33 patients with treatment-naïve nAMD. The eyes received three monthly aflibercept injections followed by five bi-monthly regimens (total 50 weeks). The structural parameters including central subfield thickness (CST) and 5 mm pigment epithelial detachment (PED) volume and microvascular parameters including macular neovascularization (MNV) area, vessel density (VD), and vessel length density (VLD) were recorded every before and 1 week after treatment. RESULTS: Patients who gained > 5 letters of best-corrected visual acuity (BCVA) from the baseline showed greater decreases in VD and VLD during the loading phase. Patients without recurrent or persistent fluid during the maintenance phase showed greater decreases in CST and 5 mm PED volume after the first injection. The decrease in mean VD during the loading phase was significantly correlated with the final BCVA (r = -0.820, p = 0.004). Moreover, the decrease in mean VLD during the loading phase was significantly correlated with the improvement in the final BCVA (r = -0.726, p = 0.017). CONCLUSIONS: The decrease in mean VD during the loading phase was significantly negatively correlated with the final BCVA at the last visit. The decrease in mean VLD during the loading phase, mean CST during the loading phase, and the improvement in final BCVA showed significant correlations. Therefore, early changes in OCTA microvascular and OCT structural parameters could help predict clinical outcomes in nAMD. TRIAL REGISTRATION: The trial was registered with the Clinical Research Information Service (CRIS), which joined the WHO International Clinical Trials Registry Platform (ICTRP) (Registration number: KCT0007375, Date of first trial registration: 10/06/2022).

Semi-automated algorithm using directional filter for the precise quantification of non-perfusion area on widefield swept-source optical coherence tomography angiograms.

Background: The clinical application of optical coherence tomography angiography (OCTA) has been well documented in literature with its promising potential in dye-less evaluation of various retinal vascular pathologies. Recent advances in OCTA help us gather wider field of view with 12 mm × 12 mm and montage compared to the standard dye-based scans, which has a higher accuracy and sensitivity in detection of peripheral pathologies. The aim of this study is to build a semi-automated algorithm to precisely quantify the non-perfusion areas (NPAs) on widefield swept-source optical coherence tomography angiography (WF SS-OCTA). Methods: All subjects underwent imaging on 100 kHz SS-OCTA device acquiring 12 mm × 12 mm angiograms centered on fovea and optic disc. After a comprehensive literature review, a novel algorithm using FIJI (ImageJ) was designed to calculate the NPAs (mm2) after excluding the threshold and segmentation artifact areas from the total field of view. Segmentation and threshold artifacts were first removed from enface structure images using the spatial variance and mean filter respectively. Vessel enhancement was achieved by using 'Subtract Background' followed by directional filter. The cut off for Huang's fuzzy black and white thresholding was defined from the pixel values based of the foveal avascular zone. Then, the NPAs were calculated using the 'Analyze Particles' command with a minimum size of ~0.15 mm2. Finally, the artifact area was subtracted from to give the corrected NPAs. Results: Our cohort had 44 eyes of 30 control patients and 107 eyes of 73 patients with diabetes mellitus (both median age 55 years, P=0.89). Of 107 eyes, 21 eyes had no evidence of diabetic retinopathy (DR), 50 eyes had non-proliferative DR and 36 eyes had proliferative DR. The median NPA was 0.20 (0.07-0.40) in controls, 0.28 (0.12-0.72) in no DR, 5.54 (3.12-9.10) in non-proliferative DR and 13.38 (8.73-26.32) in proliferative DR eyes. Using mixed effects-multiple linear regression analysis adjusting for age, there was significant progressive increase in NPA with increasing DR severity. Conclusions: This is one of the first study to use the directional filter for WFSS-OCTA image processing which is known to be superior to other Hessian based multiscale, linear, and non-linear filters especially for vascular analysis. Our method could greatly refine and streamline the calculation of signal void area proportion, while being much quicker and accurate than manual delineation of NPAs and subsequent estimation. This combined with the wide field of view can have a great prognostic and diagnostic clinical impact for future applications in DR and other ischemic retinal pathologies.

Early changes to retinal structure in patients with diabetic retinopathy as determined by ultrawide swept-source optical coherence tomography-angiography.

Purpose: To investigate retinal vascular changes in patients with diabetic retinopathy (DR) using the newly developed ultrawide rapid scanning swept-source optical coherence tomography angiography (SS-OCTA) device. Methods: This cross-sectional, observational study enrolled 24 patients (47 eyes) with DR, 45 patients (87 eyes) with diabetes mellitus (DM) without DR, and 36 control subjects (71 eyes). All subjects underwent 24 × 20 mm SS-OCTA examination. Vascular density (VD) and the thickness of the central macula (CM; 1 mm diameter) and temporal fan-shaped areas of 1-3 mm (T3), 3-6 mm (T6), 6-11 mm (T11), 11-16 mm (T16), and 16-21 mm (T21) were compared among groups. The VD and the thicknesses of the superficial vascular complex (SVC) and deep vascular complex (DVC) were analyzed separately. The predictive values of VD and thickness changes in DM and DR patients were evaluated by receiver operating characteristic (ROC) curve analysis. Results: The average VDs of the SVC in the CM and the T3, T6, T11, T16, and T21 areas were significantly lower in the DR than in the control group, whereas only the average VD of the SVC in the T21 area was significantly lower in the DM group. The average VD of the DVC in the CM was significantly increased in the DR group, whereas the average VDs of the DVC in the CM and T21 area were significantly decreased in the DM group. Evaluation of the DR group showed significant increases in the thicknesses of SVC-nourishing segments in the CM and T3, T6, and T11 areas and significant increases in the thicknesses of DVC-nourishing segments in the CM and T3 and T6 areas. In contrast, none of these parameters showed significant changes in the DM group. ROC curve analysis showed that the average VD of the SVC in the CM, T3, and T21 had better ability to predict DR, with areas under the ROC curves (AUCs) of 0.8608, 0.8505, and 0.8353, respectively. The average VD of the DVC in the CM was also predictive of DR, with an AUC of 0.8407. Conclusions: The newly developed ultrawide SS-OCTA device was better able to reveal early peripheral retinal vascular changes than traditional devices.

Peripapillary microvasculature changes after vitrectomy in epiretinal membrane via swept-source OCT angiography.

PURPOSE: To evaluate the peripapillary microvasculature changes in patients with epiretinal membrane (ERM) following pars plana vitrectomy (PPV) with internal limiting membrane (ILM) peeling using swept-source optical coherence tomography angiography (SS-OCTA). METHOD: Medical records and multimodal imaging data of 33 eyes after PPV for ERM were retrospectively reviewed. Peripapillary SS-OCTA images of 6×6 mm2 were recorded at at pre- and post-operatively every 6 months for 1 year. A semi-automated method was used to analyzed SS-OCTA images, excluding the optic disc area, using the MATLAB software. The peripapillary vessel density (pVD) of superficial capillary plexus (SCP) and deep capillary plexus (DCP) was quantified in four quadrants (superior, inferior, nasal and temporal). RESULT: The mean pVD in SCP and DCP decreased at 6- and 12-months follow-up. In sectoral analysis, superior, inferior, and temporal quadrants pVD in SCP and DCP were significantly reduced at 1 year after vitrectomy (all p < 0.05). Meanwhile, inferior quadrants pVD in SCP and DCP showed the earliest significant reduction at 6-months (p = 0.022 and 0.048, respectively). A reduction of post-operative mean pVD in DCP was significantly greater in patients with diabetic retinopathy (p = 0.043). CONCLUSION: Peripapillary capillary density significantly decreased after surgical removal of ERM. Vitrectomy with ILM peeling can cause peripapillary microvascular damage starting in inferior sector.

Comparison of retinochoroidal microvascular circulation in menstrual and postmenopausal periods using swept-source optical coherence tomography angiography.

PURPOSE: We aimed to examine the possible effects of the postmenopausal period on retinal and choroidal microvascular circulation using swept-source optical coherence tomography angiography (SS-OCTA). METHODS: This cross-sectional study included 45 eyes of 45 subjects in menstrual group and 40 eyes of 40 subjects in postmenopausal group. SS-OCTA was used for the assessment of vessel density (VD), foveal avascular zone (FAZ), choroidal thickness (CT), choriocapillaris VD, central macular thickness (CMT), nerve fiber layer thickness (RNFL), and ganglion cell layer (GCL) measurements. RESULT: The VDs of the superficial capillary plexus (SCP) and deep capillary plexus (DCP) measurements were similar in both group. FAZ area was wider in postmenopausal group (0.305 mm2 (range, 0.212-0.498 mm2)) compared to menstrual group (0.271 mm2 (range, 0.131-0.464 mm2)) (p = 0.013). Choriocapillaris VD was significantly lower in postmenopausal group (p = 0.049). CT was thicker in the postmenopausal group, but with no statistically significant difference (p = 0.066). Central macular thickness, RNFL, and GCL were similar in both groups. CONCLUSION: This is the first study in the literature to evaluate the retinochoroidal microcirculation in the menstrual and postmenopausal periods with SS-OCTA. We observed an increase in both superficial and deep FAZ area and a decrease in choroidal blood flow in the postmenopausal period. We think that this enlargement in the FAZ area may be related to the decreased amount of estrogen.