Structural OCT and OCT angiography biomarkers associated with the development and progression of geographic atrophy in AMD.

BACKGROUND: Geographic atrophy (GA) is an advanced, irreversible, and progressive form of age-related macular degeneration (AMD). Structural optical coherence tomography (OCT) and OCT angiography (OCTA) have been largely used to characterize this stage of AMD and, more importantly, to define biomarkers associated with the development and progression of GA in AMD. METHODS: Articles pertaining to OCT and OCTA biomarkers related to the development and progression of GA with relevant key words were used to search in PubMed, Researchgate, and Google Scholar. The articles were selected based on their relevance, reliability, publication year, published journal, and accessibility. RESULTS: Previous reports have highlighted various OCT and OCTA biomarkers linked to the onset and advancement of GA. These biomarkers encompass characteristics such as the size, volume, and subtype of drusen, the presence of hyperreflective foci, basal laminar deposits, incomplete retinal pigment epithelium and outer retinal atrophy (iRORA), persistent choroidal hypertransmission defects, and the existence of subretinal drusenoid deposits (also referred to as reticular pseudodrusen). Moreover, biomarkers associated with the progression of GA include thinning of the outer retina, photoreceptor degradation, the distance between retinal pigment epithelium and Bruch's membrane, and choriocapillaris loss. CONCLUSION: The advent of novel treatment strategies for GA underscores the heightened need for prompt diagnosis and precise monitoring of individuals with this condition. The utilization of structural OCT and OCTA becomes essential for identifying distinct biomarkers associated with the initiation and progression of GA.

OCT risk factors for 2-year foveal involvement in non-treated eyes with extrafoveal geographic atrophy and AMD.

PURPOSE: To assess the relationship of optical coherence tomography (OCT) findings and progression to foveal atrophy in a cohort of eyes with extrafoveal geographic atrophy (GA) and age-related macular degeneration (AMD) at inclusion. METHODS: We retrospectively analyzed 45 participants (45 eyes) with extrafoveal GA at baseline and with 2 years of regular follow-ups. Several OCT qualitative features (i.e., presence of foveal flat pigment epithelium detachment with a thin double layer sign [DLS] and reticular pseudodrusen, GA focality) and quantitative measurements (outer retinal layer thickness, retinal pigment epithelium [RPE] to Bruch's membrane [BM] volume, minimum distance from the central foveal circle, and untransformed GA lesion size area) were assessed at baseline. Logistic regression analyses were carried out to identify independent significant predictors and compute odds ratios (ORs) for the risk of the development of atrophy. RESULTS: At month 24, 26 eyes (57.8%) developed atrophy in the foveal central circle, while 11 eyes (24.4%) developed atrophy in the foveal central point. Significant independent predictive features for the development of atrophy in the foveal central circle included foveal outer retinal thickness (OR, 0.867; p = 0.015), minimum distance from the foveal central circle (OR, 0.992; p = 0.022), and foveal thin DLS (OR, 0.044; p = 0.036). The only independent predictive feature for the development of atrophy in the foveal central point was the presence of foveal thin DLS (OR, 0.138; p = 0.017). CONCLUSIONS: We identified OCT risk factors for 2-year foveal atrophy in eyes with untreated extrafoveal GA at baseline.

Platelet concentrates in macular hole surgery. A journey through the labyrinth of terminology, preparation, and application: a comprehensive review.

The surgical management of macular holes is undergoing continuous evolution, with recent focus on the utilization of platelet concentrates as a promising adjunctive intervention. Currently, they present a valid surgical approach for achieving anatomical and functional success with a non-inferiority comparably to the alternative surgical techniques. Nonetheless, the utilization of varied platelet concentrates terminologies, coupled with the lack of standardization in their preparation methodologies, engenders both lexical confusion and challenges in comparing scientific studies published up until now. In this review, we summarized the published evidence concerning the application of platelet concentrates in macular holes surgery, aiming to clarify the terminology and methodologies employed and to establish a common consensus facilitating further development and diffusion of this promising technique.

The "triple-layer sign": an optical coherence tomography signature for the detection of non-exudative macular neovascularization.

PURPOSE: To assess the sensitivity and specificity of the "triple layer sign" (TLS) (retinal pigment epithelium (RPE), neovascular tissue, and Bruch's membrane) on structural optical coherence tomography (OCT) images for the diagnosis of treatment-naïve non-exudative type-1 macular neovascularization (NE-MNV) in age-related macular degeneration (AMD). DESIGN: Cross-sectional study. METHODS: Two masked retinal experts evaluated the presence of the TLS in eyes with NE-MNV and controls with an RPE elevation without exudation due to other causes than NE-MNV in AMD [e.g., medium-large drusen, cuticular drusen, basal laminar deposits (BlamD)]. RESULTS: 130 eyes of 98 consecutive patients met the study criteria; 40 eyes of 40 patients satisfied the criteria for being included in the NE-MNV secondary to AMD group (27 females, 13 males, with a mean age of 73.8 ± 8.0 years), and 90 eyes of 58 patients met the criteria to be included in the control group (31 eyes were included in the medium-to-large drusen sub-group, 32 eyes in the cuticular drusen sub-group, and 27 eyes in the BlamD group. The TLS was observed in 39/40 patients with NE-MNV and 8/90 controls. The sensitivity and specificity of the TLS for the diagnosis of NE-MNV were 97% and 91%, respectively. CONCLUSIONS: The TLS on OCT demonstrated high sensitivity and specificity values in detecting treatment-naive type 1 NE-MNV.

Peripapillary hyperreflective ovoid mass-like structures (PHOMS) in patients with acute Leber's hereditary optic neuropathy.

PURPOSE: Peripapillary hyperreflective ovoid mass-like structures (PHOMS) represent an optical coherence tomography (OCT) finding that has been characterized in different forms of pseudopapilledema. The aim of this study was to investigate the prevalence of PHOMS in patients affected by acute LHON using structural OCT, and to provide a detailed description of these findings. METHODS: Patients with a clinical and molecularly confirmed diagnosis of acute LHON (visual loss having occurred less than 6 months) were enrolled from the neuro-ophthalmology clinic at San Raffaele Scientific Institute. Patients had a complete ophthalmologic evaluation, including imaging with structural OCT. RESULTS: Our analysis included 16 patients (21 eyes-8 males and 8 females) with acute LHON. Structural OCT exhibited PHOMS in 12 eyes from 9 patients with a prevalence rate of 57.1%. In a subsequent topographical assessment in the peripapillary area, the most common location of PHOMS was the temporal region (12 out of 12 eyes), while the nasal region was affected in 2 eyes (16.7%). Considering the 12 eyes with PHOMS, mean ± SD temporal peripapillary RNFL thickness was 87.5 ± 28.4 microns. The temporal peripapillary RNFL thickness was significantly lower in eyes without PHOMS (63.7 ± 32.2 microns; P = 0.40). At the 12-month follow-up visit, PHOMS disappeared in 10 out of 12 eyes. CONCLUSIONS: Acute LHON eyes have PHOMS which are mainly confined to the temporal peripapillary sector. PHOMS may represent swelled retinal fibers that have herniated or are in stasis.

INTERSESSION REPEATABILITY OF READING PERFORMANCE MEASURES IN PATIENTS WITH NEOVASCULAR AGE-RELATED MACULAR DEGENERATION.

PURPOSE: To assess the intersession repeatability of reading performance measures in patients with previously treated neovascular age-related macular degeneration and good best-corrected visual acuity (≥20/40 Snellen). METHODS: Ninety-one patients (91 eyes) with a diagnosis of previously treated neovascular age-related macular degeneration and good best-corrected visual acuity (≥20/40 Snellen) were prospectively enrolled. Reading performance metrics were assessed using Radner charts, and these measurements were repeated after 7 days to obtain the intersession repeatability. To test repeatability, we calculated the intraclass correlation coefficient, the 95% coefficient of repeatability, and the coefficient of variation for each reading parameter: 1) reading acuity (RA-LogRAD); 2) maximal reading speed-words per minute; 3) RA score (RA score-LogRAD); and 4) critical print size-LogRAD. RESULTS: Mean ± standard deviation best-corrected visual acuity was 0.13 ± 0.01 logMAR [range: 0.00-0.30 logMAR]. The intraclass correlation coefficient values indicated a good reliability for all the analyzed metrics (0.901 for RA; 0.859 for max reading speed; 0.906 for RA score; and 0.868 for critical print size). The coefficient of repeatability was 0.2 LogRAD for RA, 63.2 words per minute for max reading speed, 0.2 LogRAD for RA score, and 0.2 LogRAD for critical print size. Coefficient of variation was 5.5% for RA, 8.9% for max reading speed, 5.8% for RA score, and 6.9% for critical print size. CONCLUSION: Reading performance metrics are characterized by good values of intersession repeatability in patients with neovascular age-related macular degeneration with good best-corrected visual acuity. Our findings may grant the employment of such measures in trials assessing the visual outcome in these patients.

LONG-TERM VISUAL OUTCOMES AND OPTICAL COHERENCE TOMOGRAPHY BIOMARKERS IN EYES WITH MACULAR EDEMA SECONDARY TO RETINAL VEIN OCCLUSION FOLLOWING ANTI-VASCULAR ENDOTHELIAL GROWTH FACTOR THERAPY.

PURPOSE: To evaluate the structural characteristics and long-term visual outcomes in eyes impacted by macular edema as a consequence of retinal vein occlusion that has undergone effective treatment with anti-vascular endothelial growth factor therapy. METHODS: Inclusion criteria comprised 42 eyes of 41 patients, subjected to long-term follow-up, displaying resolved macular edema after a minimum of 5 years since the commencement of anti-vascular endothelial growth factor therapy. During the final visit, two experienced observers evaluated several qualitative parameters using spectral-domain optical coherence tomography, such as the integrity of the external limiting membrane, the state of the ellipsoid zone and retinal pigment epithelium, and the presence of disorganization of the retinal inner layers. In addition, a quantitative evaluation of the inner and outer retinal thicknesses was conducted for the purpose of topographical analysis. RESULTS: The most prominent qualitative correlation identified with best-corrected visual acuity during the final visit was connected to the presence of disorganization of the retinal inner layers ( P = 0.004) and the integrity of the external limiting membrane ( P = 0.015). In relation to quantitative aspects, a noteworthy correlation was noted between the visual acuity during the last visit and the parafoveal thickness in both the inner ( P = 0.003) and outer retina ( P = 0.018). CONCLUSION: In eyes where macular edema resulting from retinal vein occlusion has been successfully resolved with anti-vascular endothelial growth factor therapy, changes in the status of the external limiting membrane and the presence of disorganization of the retinal inner layers serve as valuable optical coherence tomography biomarkers, indicating prolonged visual outcomes.

Deep Learning in Neovascular Age-Related Macular Degeneration.

Background and objectives: Age-related macular degeneration (AMD) is a complex and multifactorial condition that can lead to permanent vision loss once it progresses to the neovascular exudative stage. This review aims to summarize the use of deep learning in neovascular AMD. Materials and Methods: Pubmed search. Results: Deep learning has demonstrated effectiveness in analyzing structural OCT images in patients with neovascular AMD. This review outlines the role of deep learning in identifying and measuring biomarkers linked to an elevated risk of transitioning to the neovascular form of AMD. Additionally, deep learning techniques can quantify critical OCT features associated with neovascular AMD, which have prognostic implications for these patients. Incorporating deep learning into the assessment of neovascular AMD eyes holds promise for enhancing clinical management strategies for affected individuals. Conclusion: Several studies have demonstrated effectiveness of deep learning in assessing neovascular AMD patients and this has a promising role in the assessment of these patients.

Individual vs. combined imaging modalities for diagnosing neovascular central serous chorioretinopathy.

PURPOSE: To assess the diagnostic accuracy of individual and combined imaging modalities compared with multimodal imaging for the detection of choroidal neovascularization (CNV) in central serous chorioretinopathy (CSC). METHODS: We analyzed patients with CSC with and without CNV who had indocyanine green angiography (ICGA), structural optical coherence tomography (OCT), and OCT angiography (OCTA) obtained on the same day. The presence of CNV was determined using multimodal imaging by a senior retina specialist (i.e., diagnostic reference). Individual and combined (i.e., ICGA + structural OCT) imaging modalities were then graded by two expert readers for the presence of CNV. Sensitivity, specificity, positive (PPV), and negative (NPV) predictive values were computed for individual and combined imaging modalities relative to the diagnostic reference. RESULTS: CNV was detected in 17 eyes in 17 out of 33 CSC patients according to the reference standard. Using ICGA, the identification of CNV had a sensitivity of 66.7%, specificity of 66.7%, PPV of 70.6%, and NPV of 62.5%. Structural OCT had the following diagnostic accuracy values: 83.3% of sensitivity, 53.3% of specificity, 68.1% of PPV, and 72.7% of NPV. Using OCTA, CNV was graded to be present with a sensitivity of 77.8%, specificity of 86.7%, PPV of 87.5%, and NPV of 76.5%. The combination of ICGA and structural OCT granted the identification of CNV with a sensitivity of 83.3%, specificity of 86.7%, PPV of 88.2%, and NPV of 81.3%. CONCLUSIONS: OCTA has an elevated diagnostic accuracy in identifying CSC-associated CNV, though a combination of ICGA and structural OCT has a comparable diagnostic efficiency.

PREVALENCE AND MORPHOLOGIC BIOMARKERS OF METAMORPHOPSIA IN EYES WITH "RESOLVED" CHRONIC CENTRAL SEROUS CHORIORETINOPATHY.

PURPOSE: To assess relationships between demographics, clinical characteristics, and optical coherence tomography characteristics with persistence of metamorphopsia after resolution of subretinal fluid in eyes with chronic central serous chorioretinopathy. METHODS: One-hundred participants with "resolved" (absence of subretinal fluid) chronic central serous chorioretinopathy were retrospectively analyzed. Patients underwent a complete ophthalmologic evaluation, including assessment of the presence of metamorphopsia. At the study visit, optical coherence tomography scans were reviewed for qualitative and quantitative features. RESULTS: Sixty-six of 100 patients (66.0%) complained of metamorphopsia. Both the foveal and parafoveal ganglion cell complex thicknesses were thinner in central serous chorioretinopathy eyes with metamorphopsia (35.1 ± 10.6 µ m and 82.0 ± 18.1 µ m vs. 40.7 ± 11.8 µ m and 93.1 ± 13.5 µ m, P = 0.030 and P < 0.0001). In the foveal region, the outer plexiform layer and outer nuclear layer thicknesses were thinner in patients with metamorphopsia (24.6 ± 8.5 µ m and 63.1 ± 20.9 µ m vs. 29.1 ± 8.7 and 76.2 ± 18.2 µ m, P = 0.016 and P = 0.005). The ellipsoid zone band was more frequently discontinued in eyes with metamorphopsia (56.1% vs. 35.3%, P = 0.039). Multivariate stepwise linear regression analysis demonstrated that the strongest associations with the presence of metamorphopsia were with parafoveal ganglion cell complex thickness ( P = 0.004), foveal outer nuclear layer thickness ( P = 0.010), and number of previous recurrences of subretinal fluid accumulation ( P = 0.017). The time interval from the last subretinal fluid resolution was not associated with the presence of metamorphopsia. CONCLUSION: In "resolved" central serous chorioretinopathy, clinical aspects (i.e., number of previous recurrences) and structural changes (i.e., ganglion cell complex and outer nuclear layer thinning) are associated with metamorphopsia after subretinal fluid resolution.

CHOROIDAL VASCULARITY INDEX IN HYDROXYCHLOROQUINE TOXIC RETINOPATHY: A Quantitative Comparative Analysis Using Enhanced Depth Imaging In Spectral Domain Optical Coherence Tomography.

PURPOSE: To investigate choroidal involvement in eyes of patients treated with hydroxychloroquine (HCQ), by quantifying the choroidal vascularity index (CVI) and other choroidal biomarkers. METHODS: Vertical enhanced depth imaging spectral domain optical coherence tomography (SD-OCT) scans were performed in eyes with either advanced-stage or mild HCQ toxic retinopathy, as well as in healthy age-matched and sex-matched controls. Based on SD-OCT scans, the subfoveal and mean choroidal thickness (ChT) was measured. The CVI, total choroidal area (TCA), luminal choroidal area (LCA), and stromal choroidal area (SCA) were calculated based on a binarization image process. These variables were computed and compared between the three groups (i.e., advanced stage, mild toxicity, and healthy controls). RESULTS: Forty-eight eyes of 47 patients under HCQ (26 eyes presented with advanced stage HCQ toxicity and 22 eyes with mild toxicity) and 34 eyes of 31 healthy controls were included. Both CVI and ChT were significantly different between the three groups ( P < 0.001, P < 0.001). When comparing the advanced stage toxicity group to healthy controls, both the subfoveal and the mean ChT were diminished ( P < 0.001). The CVI, TCA, LCA, and SCA were significantly lower in the advanced stage of toxicity group when compared with controls ( P < 0.001, <0.00001, <0.0001, and P = 0.0094, respectively). CONCLUSION: Our study suggests that eyes with HCQ toxic retinopathy, especially at advanced stages, present with choroidal impairment, giving further pathophysiological insights into the unfolding of this retinal toxicity.

Pushing Retinal Imaging Forward: Innovations and Their Clinical Meaning - The 2022 Ophthalmologica Lecture.

Retinal imaging has greatly expanded our understanding of various pathological conditions. This article presents a summary of the key points covered during the 2022 Ophthalmologica Lecture held at the Euretina Congress in Hamburg. The first part of the article focuses on the use of optical coherence tomography angiography to examine and comprehend the choroid in age-related macular degeneration (AMD). Subsequently, we delve into the discussion of the "postreceptor neuronal loss" theory in AMD, which was studied using en face structural optical coherence tomography (OCT). Following that, we explore pertinent findings obtained through cross-sectional OCT in retinal and optic nerve diseases, such as AMD, diabetic macular edema, pathologic myopia, central serous chorioretinopathy, and Leber's hereditary optic neuropathy.

Neovascular age-related macular degeneration: advancement in retinal imaging builds a bridge between histopathology and clinical findings.

PURPOSE: To provide a review of the salient histological and imaging features in neovascular age-related macular degeneration (AMD) that will be integrated in order to have a better comprehension of the pathogenesis and clinical aspects of this disease. METHODS: A literature review of histology and imaging features in neovascular AMD was conducted. RESULTS: Histology has granted a detailed characterization of neovascular AMD ex vivo. In details, histological features in these eyes have offered important insights into the pathogenesis of neovascular AMD. In addition, histology donated a detailed characterization of the different types of macular neovascularization (MNV) that may complicate AMD. The introduction of optical coherence tomography angiography (OCTA) has enormously amplified our knowledge of neovascular AMD through in vivo assessment of the anatomical and pathological characteristics of this disease. New insights elucidating the morphological features of the choriocapillaris confirmed that this vascular structure plays a crucial role in the pathogenesis of neovascular AMD. OCTA also offered a detailed visualization of MNV complicating neovascular AMD. CONCLUSIONS: New imaging technologies offer a remarkable chance to build a bridge between histology and clinical findings in neovascular AMD.

Choroidal vascularity index in eyes with central macular atrophy secondary to age-related macular degeneration and Stargardt disease.

PURPOSE: To compare macular atrophy (MA) secondary to age-related macular degeneration (AMD) and Stargardt disease (STGD) using the choroidal vascularity index (CVI). METHODS: In this multicentric retrospective study, two distinct cohorts were collected: patients with MA secondary to AMD and MA secondary to STGD. All patients were investigated using a multimodal imaging approach, including CVI in the subfoveal 1000 µm area. Of note, the CVI is not influenced by aging, which allows comparisons between different cohorts. RESULTS: Seventy eyes were included: 35 eyes of 35 patients (mean age 78 ± 7 years) in the AMD group and 35 eyes of 35 patients (mean age 41 ± 16 years, p < 0.001) in the STGD group. Choroidal thickness was significantly lower in the AMD group in comparison to the STGD group (151 ± 80 µm vs 353 ± 105 µm, p < 0.001). The total choroidal area (TCA) was significantly greater in the STGD group in comparison to the AMD group (1.734 ± 0.958 mm2 vs 0.538 ± 0.391 mm2, respectively, p < 0.001). Interestingly, the CVI was significantly lower in AMD patients in comparison to STGD patients (27.322 ± 15.320% vs 49.880 ± 7.217%, respectively, p < 0.001), and this difference was confirmed in the subgroup of patients over 50 years old. CONCLUSION: Our results corroborate the hypothesis that large choroidal vessels were impaired to a greater extent in AMD than in STGD. CVI may help in differentiating AMD from STGD in the presence of MA, better understanding of the pathogenesis, and monitoring of therapeutic response.

CONVENTIONAL INTERNAL LIMITING MEMBRANE PEELING VERSUS INVERTED FLAP FOR SMALL-TO-MEDIUM IDIOPATHIC MACULAR HOLE: A Randomized Trial.

PURPOSE: To compare conventional internal limiting membrane (ILM) peeling versus inverted flap technique in small-to-medium idiopathic macular hole. METHODS: Eyes with ≤400 µ m idiopathic macular holes were randomized into the conventional ILM peeling group (25 eyes) and inverted flap group (25 eyes). A 12-month follow-up was considered. Macular sensitivity (MS) change detected with MP-1 microperimetry was the primary outcome. Secondary outcomes included best-corrected visual acuity change, closure rate, anatomical findings on optical coherence tomography such as U-shape foveal contour, restoration of external limiting membrane, and ellipsoid zone. RESULTS: In both groups, MS improved throughout the follow-up. Final MS was greater in the conventional ILM peeling group compared with the inverted flap group, being 16.6 ± 2.3 dB versus 14.9 ± 2.9 dB, respectively ( P = 0.026). In both groups best-corrected visual acuity improved throughout the follow-up, with a final best-corrected visual acuity of 0.19 ± 0.14 logMar (20/31 Snellen) in the conventional ILM group and 0.22 ± 0.11 logMar (20/33 Snellen) in the inverted flap group ( P = 0.398). Anatomical hole closure was achieved in all cases. No difference in optical coherence tomography findings was shown between the two groups. CONCLUSION: A better final MS was found in eyes undergoing conventional ILM peeling. Inverted flap technique has disadvantages compared with conventional peeling for the treatment of small-to-medium idiopathic macular holes.

CHOROIDAL AMYLOID DEPOSITION: A Multicenter Study of Amyloid Lesions Identified in Late Indocyanine Green Angiography.

PURPOSE: To characterize choroidal amyloid angiopathy (CAA) using late-phase indocyanine green angiography (ICGA). METHODS: This was a multicenter retrospective observational case series on patients with transthyretin (ATTR) and AL amyloidosis who underwent ICGA. The timing of hyperfluorescence and longitudinal changes were analyzed. RESULTS: Thirty-two patients (27 with ATTR and 5 with AL) with mean age of 58.9 ± 17.4 years were included. Hyperfluorescent spots in the very late phases of ICGA, corresponding to CAA, were observed in 49 of 55 eyes (89%). The median time to maximal staining was 672 (95% confidence interval, 644-752) seconds, which was significantly later than the initial staining (503 [95% confidence interval, 447-521], P < 0.0001; Wilcoxon signed rank test). In seven patients with ATTR amyloidosis who underwent follow-up of ICGA, the CAA was stable in two patients and improved in five patients during treatment. However, 3 patients (43%) had worsening vitreous opacities in both eyes, and 4 patients (57%) developed secondary open-angle glaucoma. CONCLUSION: Most patients with amyloidosis were found to have CAA on ICGA. Up to 12.5 minutes is required for maximal ICG staining. Choroidal amyloid angiopathy improved in most patients with systemic treatment and may serve as a marker of systemic disease status.

INNER AND OUTER CHOROIDAL CHANGES IN THE FELLOW EYE OF PATIENTS WITH UNILATERAL CENTRAL SEROUS CHORIORETINOPATHY.

PURPOSE: To quantitatively evaluate the inner and outer choroidal changes in the fellow eyes of patients with unilateral central serous chorioretinopathy (CSC). METHODS: We analyzed data from patients with a diagnosis of unilateral CSC who had structural optical coherence tomography (OCT) and swept-source OCT angiography obtained. An additional group of age-matched healthy patients was included for comparison. The main outcome measures were: (1) choriocapillaris flow deficits' quantitative metrics; (2) choroidal luminal (LCA) and stromal (SCA) areas; and (3) choroidal vascularity index. RESULTS: Fellow unaffected eyes from 60 patients with unilateral CSC and 30 healthy subjects were included in the analysis. Mean ± SD age was 47.5 ± 9.9 years in the unilateral CSC group and 50.7 ± 10.8 years in the control group (P = 0.410). In the structural OCT assessment, both the LCA and SCA were increased in the unilateral CSC group (0.33 ± 0.11 and 0.29 ± 0.10 mm2) compared with healthy controls (0.28 ± 0.08 and 0.27 ± 0.05 mm2), although only differences in LCA reached a statistical significance (P = 0.041 and P = 0.286 for LCA and SCA, respectively). The choroidal vascularity index was higher in CSC patients (53.7 ± 3.6 and 50.9 ± 5.5%, P = 0.045). In the OCT angiography evaluation, the choriocapillaris flow deficits' percentage and number were increased in those patients affected by unilateral CSC. In multiple regressions, the strongest association with choriocapillaris percentage of flow deficits was with the presence of pachychoroid pigment epitheliopathy signs in the study eye (P < 0.0001). CONCLUSION: Our results corroborate the hypothesis that inner and outer choroidal changes affect both eyes of patients with unilateral disease.

CHOROIDAL VASCULARITY INDEX IS ASSOCIATED WITH GEOGRAPHIC ATROPHY PROGRESSION.

PURPOSE: To investigate the correlation between choroidal vascularity index and the enlargement of geographic atrophy (GA) lesion secondary to age-related macular degeneration during the 2-year follow-up. METHODS: In this longitudinal observational study, 26 eyes (26 patients, mean age 75.7 ± 8.8 years) affected by GA were included. Choroidal vascularity index was calculated in the subfoveal 3000-µm area. The main outcome measure included correlation analysis between baseline choroidal vascularity index and the rate of GA enlargement. RESULTS: During the 2-year follow-up, the mean GA area increased from 6.99 ± 5.28 mm2 to 10.69 ± 6.61 mm2(P < 0.001), accounting for a growth rate of 0.35 ± 0.20 and 0.31 ± 0.17 mm/year after the square root transformation in the first and second year of follow-up, respectively. Stromal choroidal area significantly decreased during the 2-year follow-up (P = 0.002). Interestingly, there was a significant correlation between the baseline choroidal vascularity index and the rate of GA enlargement (r=-0.432, P = 0.027) and between stromal choroidal area and the rate of GA enlargement (r = 0.422, P = 0.032). No other significant relationship was disclosed among choroidal parameters with the rate of GA enlargement. CONCLUSION: Choroidal vascularity index impairment is strictly related to the rate of GA enlargement during the 1-year and 2-year follow-up in patients affected by GA. For this reason, choroidal vascularity index could be considered a predictor of GA progression in the clinical setting, and it could be considered as a new potential biomarker in the efficacy evaluation of new GA interventions.

USING THREE-DIMENSIONAL OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY METRICS IMPROVES REPEATABILITY ON QUANTIFICATION OF ISCHEMIA IN EYES WITH DIABETIC MACULAR EDEMA.

PURPOSE: Two-dimensional (2D) optical coherence tomography angiography (OCTA) is known to be prone to segmentation errors, especially in pathologic eyes. Therefore, our aim was to systematically compare intrasession repeatability between repeated scans for 2D and three-dimensional (3D) OCTA metrics in quantifying retinal perfusion in eyes with diabetic macular edema. METHODS: Diabetic patients with diabetic retinopathy and diabetic macular edema who had two consecutive OCTA imaging scans obtained during the same visit were retrospectively included. A previously validated algorithm was applied to OCTA volume data to measure the 3D vascular volume and perfusion density. Optical coherence tomography angiography en face images were also processed to obtain 2D perfusion density metrics. RESULTS: Twenty patients (20 eyes) with diabetic retinopathy and diabetic macular edema were included. The intraclass correlation coefficient ranged from 0.591 to 0.824 for 2D OCTA metrics and from 0.935 to 0.967 for 3D OCTA metrics. Therefore, compared with the 2D OCTA analysis, the intraclass correlation coefficients of the 3D OCTA analysis were higher (without overlapping of the 95% confidential intervals). Similarly, the coefficient of variation (ranging from 2.2 to 4.2 for 2D OCTA metrics and from 1.9 to 2.0 for 3D OCTA metrics) indicated that the 3D OCTA-based quantifications had the highest interscan intrasession agreements. Differences in interscan 2D OCTA metrics' values were associated with average macular volume. CONCLUSION: Three-dimensional OCTA metrics have higher values of intrasession repeatability, as compared with 2D OCTA metrics. The latter finding seems to be related to the high rate of segmentation errors occurring in diabetic macular edema eyes.

OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY ASSESSMENT OF THE DIABETIC MACULA: A Comparison Study Among Different Algorithms.

PURPOSE: To assess the impact of histogram adjustments and binarization thresholding selection on quantitative measurements of diabetic macular ischemia using optical coherence tomography angiography (OCTA). METHODS: Patients with diabetic retinopathy (DR) who had swept-source OCTA imaging obtained were enrolled. An additional group of 15 healthy control subjects was included for comparison. Previously used brightness/contrast changes and binarization thresholds were applied to original OCTA images to obtain and compare different binarized images. Qualitative and quantitative comparisons were performed. RESULTS: Thirty patients with DR (30 eyes) were included in the analysis. Fifteen eyes displayed the presence of diabetic macular edema. Qualitative grading revealed that binarized images obtained using a global threshold had better quality compared with local or multistep thresholds. The "median" filter was most frequently graded as the histogram adjustment resulting in binarized images with best quality. In the quantitative analysis, local thresholds tended to generate higher values of measured metrics. Differences in OCTA metrics between global and local thresholds were associated with presence of diabetic macular edema and signal strength index value. In the comparison between healthy and DR eyes, differences in OCTA metrics were significantly affected by binarization threshold selection. CONCLUSION: Quantitative OCTA parameters may be significantly influenced by strategies to quantify macular perfusion. Image quality and presence of macular edema can significantly impact OCTA-derived quantitative vascular measurements and differences between global and local binarization thresholds. These findings highlight the importance of consistent strategies to reliably generate quantitative OCTA metrics in patients with DR.