Sector-Based Regression Strategies to Reduce Refractive Error-Associated Glaucoma Diagnostic Bias When Using OCT and OCT Angiography.

Purpose: This cross-sectional study aimed to investigate the sectoral variance of optical coherence tomography (OCT) and OCT angiography (OCTA) glaucoma diagnostic parameters across eyes with varying degrees of refractive error. Methods: Healthy participants, including individuals with axial ametropia, enrolled in the Hong Kong FAMILY cohort were imaged using the Avanti/AngioVue OCT/OCTA system. The OCT and OCTA parameters obtained include peripapillary nerve fiber layer thickness (NFLT), peripapillary nerve fiber layer plexus capillary density (NFLP-CD), and macular ganglion cell complex thickness (GCCT). Sectoral measurements of NFLT, NFLP-CD, and GCCT were based on sectors and hemispheres. Results: A total of 1339 eyes from 791 participants were stratified based on spherical equivalent refraction: high myopia (<-6 D), low myopia (-6 D to -1 D), emmetropia (-1 D to 1 D), and hyperopia (>1 D). Multivariable broken stick regression models, accounting for age, sex, and signal strength, showed that all NFLT sectors except temporally, the inferior GCCT hemisphere, and half of the NFLP-CD sectors were more affected by ametropia-related covariates than the corresponding global parameters. As expected, the false-positive rates in those sectors were elevated. Finally, sector-specific axial length (AL) and spherical equivalent (SE) adjustments helped reduce the elevated false-positive rates. Conclusions: The effect of optical magnification is even more prominent among sectors than the global parameters. AL- and SE-based adjustments should be individualized to each sector to mitigate this magnification bias effectively. Translational Relevance: Identifying sectoral differences among diagnostic parameters and adopting these sector-based adjustments into commercial OCT systems will hopefully reduce false-positive rates related to refractive error.

Automated Macular Fluid Volume As a Treatment Indicator for Diabetic Macular Edema.

Introduction: To assess the diagnostic accuracy of automatically quantified macular fluid volume (MFV) for treatment-required diabetic macular edema (DME). Methods: This retrospective cross-sectional study included eyes with DME. The commercial software on optical coherence tomography (OCT) produced the central subfield thickness (CST), and a custom deep-learning algorithm automatically segmented the fluid cysts and quantified the MFV from the volumetric scans of an OCT angiography system. Retina specialists treated patients per standard of care based on clinical and OCT findings without access to the MFV. The main outcome measures were the area under the receiver operating characteristic curve (AUROC), sensitivity, and specificity of the CST, MFV, and visual acuity (VA) for treatment indication. Results: Of 139 eyes, 39 (28%) were treated for DME during the study period and 101 (72%) were previously treated. The algorithm detected fluid in all eyes; however, only 54 eyes (39%) met the DRCR.net criteria for center-involved ME. The AUROC of MFV predicting a treatment decision of 0.81 was greater than that of CST (0.67) (P = .0048). Untreated eyes that met the optimal threshold for treatment-required DME based on MFV (>0.031 mm3) had better VA than treated eyes (P = .0053). A multivariate logistic regression model showed that MFV (P = .0008) and VA (P = .0061) were significantly associated with a treatment decision, but CST was not. Conclusions: MFV had a higher correlation with the need for treatment for DME than CST and may be especially useful for ongoing management of DME.

Deep learning-based signal-independent assessment of macular avascular area on 6×6 mm optical coherence tomography angiogram in diabetic retinopathy: a comparison to instrument-embedded software.

SYNOPSIS: A deep-learning-based macular extrafoveal avascular area (EAA) on a 6×6 mm optical coherence tomography (OCT) angiogram is less dependent on the signal strength and shadow artefacts, providing better diagnostic accuracy for diabetic retinopathy (DR) severity than the commercial software measured extrafoveal vessel density (EVD). AIMS: To compare a deep-learning-based EAA to commercial output EVD in the diagnostic accuracy of determining DR severity levels from 6×6 mm OCT angiography (OCTA) scans. METHODS: The 6×6 mm macular OCTA scans were acquired on one eye of each participant with a spectral-domain OCTA system. After excluding the central 1 mm diameter circle, the EAA on superficial vascular complex was measured with a deep-learning-based algorithm, and the EVD was obtained with commercial software. RESULTS: The study included 34 healthy controls and 118 diabetic patients. EAA and EVD were highly correlated with DR severity (ρ=0.812 and -0.577, respectively, both p<0.001) and visual acuity (r=-0.357 and 0.420, respectively, both p<0.001). EAA had a significantly (p<0.001) higher correlation with DR severity than EVD. With the specificity at 95%, the sensitivities of EAA for differentiating diabetes mellitus (DM), DR and severe DR from control were 80.5%, 92.0% and 100.0%, respectively, significantly higher than those of EVD 11.9% (p=0.001), 13.6% (p<0.001) and 15.8% (p<0.001), respectively. EVD was significantly correlated with signal strength index (SSI) (r=0.607, p<0.001) and shadow area (r=-0.530, p<0.001), but EAA was not (r=-0.044, p=0.805 and r=-0.046, p=0.796, respectively). Adjustment of EVD with SSI and shadow area lowered sensitivities for detection of DM, DR and severe DR. CONCLUSION: Macular EAA on 6×6 mm OCTA measured with a deep learning-based algorithm is less dependent on the signal strength and shadow artefacts, and provides better diagnostic accuracy for DR severity than EVD measured with the instrument-embedded software.

Regression-Based Strategies to Reduce Refractive Error-Associated Glaucoma Diagnostic Bias When Using OCT and OCT Angiography.

Purpose: The purpose of this study was to correct refractive error-associated bias in optical coherence tomography (OCT) and OCT angiography (OCTA) glaucoma diagnostic parameters. Methods: OCT and OCTA imaging were obtained from participants in the Hong Kong FAMILY cohort. The Avanti/AngioVue OCT/OCTA system was used to measure the peripapillary nerve fiber layer thickness (NFLT), peripapillary nerve fiber layer plexus capillary density (NFLP-CD), macular ganglion cell complex thickness (GCCT), and macular superficial vascular complex vascular density (SVC-VD). Healthy eyes, including ones with axial ametropia, were enrolled for analysis. Results: A total of 1346 eyes from 792 participants were divided into 4 subgroups: high myopia (<-6D), low myopia (-6D to -1D), emmetropia (-1D to 1D), and hyperopia (>1D). After accounting for age, sex, and signal strength, multivariable regression showed strong dependence in most models for NFLT, GCCT, and NFLP-CD on axial eye length (AL), spherical equivalent (SE) refraction, and apparent optic disc diameter (DD). Optical analysis indicated that AL-related transverse optical magnification variations predominated over anatomic variations and were responsible for these trends. Compared to the emmetropic group, the false positive rates were significantly (Chi-square test P < 0.003) elevated in both myopia groups for NFLT, NFLP-CD, and GCCT. Regression-based adjustment of these diagnostic parameters with AL or SE significantly (McNemar test P < 0.03) reduced the elevated false positive rates. Conclusions: Myopic eyes are biased to have lower NFLT, GCCT, and NFLP-CD measurements. AL- and SE-based adjustments were effective in mitigating this bias. Translational Relevance: Adoption of these adjustments into commercial OCT systems may reduce false positive rates related to refractive error.

Optic disc and peripapillary vessel density measured with optical coherence tomography angiography and its associations in Chinese adults: a large population-based study.

PURPOSE: To investigate the optic disc and peripapillary vessel density, as well as its ocular and systemic associations, in healthy eyes among adult Chinese population. METHODS: A population-based cross-sectional eye survey was conducted on Chinese adults residing in Hong Kong. 1891 eyes from 1891 participants who completed 4.5×4.5 mm optical coherence tomography angiography scans were recruited. Among the 1891 eyes, 404 were excluded due to low scan quality, optic disc or retinal disorders and non-Chinese ethnicity. The vessel densities (VDs) at nerve fibre layer plexus (NFLP) at both optic disc and peripapillary were collected for analysis. Multiple linear regression analysis was performed to determine the ocular and systemic associations of NFLP VD. RESULTS: The study included 1487 participants (men: 41.2%) with a mean age of 48.8±15.4 years. The mean NFLP VD of the whole en face image, inside disc and peripapillary region was 53.8%, 42.7% and 60.3%, respectively. In the multivariable model, decreased NFLP VDs were significantly associated with older age, male gender, longer axial length (AL) and lower Signal Strength Index. CONCLUSIONS: This large population-based cross-sectional study provided quantitative data of optic disc and peripapillary NFLP VD which may serve as a normative reference for clinical use. Apart from age, gender and AL, the scan signal strength also should be taken into consideration during the assessment of NFLP VD.

Effect of algorithms and covariates in glaucoma diagnosis with optical coherence tomography angiography.

PURPOSE: To assess the effects of algorithms and covariates in glaucoma diagnosis with optical coherence tomography angiography (OCTA). METHODS: In this prospective cross-sectional study, one eye each of 36 normal controls and 64 patients with glaucoma underwent 4.5 mm disc-centred and 6 mm macula-centred OCTA scans. The peripapillary nerve fibre layer plexus capillary density (NFLP-CD) and macular superficial vascular complex vessel density (SVC-VD) were measured using both a commercial algorithm (AngioAnalytics) and a custom algorithm (Center for Ophthalmic Optics & Lasers Angiography Reading Toolkit (COOL-ART)). The nerve fibre layer and ganglion cell complex thicknesses were measured on structural OCT. RESULTS: The overall peripapillary NFLP-CD and macular SVC-VD measured with the two algorithms were highly correlated but poorly agreed. Among the normal controls, the perfusion measurements made by both algorithms were significantly correlated with age. AngioAnalytics measurements were also correlated with signal strength index, while COOL-ART measurements were not. These covariates were adjusted. The diagnostic accuracy, measured as the area under the receiver operating characteristic curve for glaucoma detection, was not significantly different between algorithms, between structural and perfusion parameters and between the peripapillary and macular regions (All p>0.05). The macular SVC-VD in the 6 mm square had a significantly higher diagnostic accuracy than that of the central 3 mm square area (p=0.005). CONCLUSIONS: AngioAnalytics and COOL-ART vessel density measurements are not interchangeable but potentially interconvertible. Age and signal strength are significant covariates that need to be considered. Both algorithms and both peripapillary and macular perfusion parameters have similarly good diagnostic accuracy comparable to structural OCT. A larger macular analytic area provides higher diagnostic accuracy.

Association Between Fluid Volume in Inner Nuclear Layer and Visual Acuity in Diabetic Macular Edema.

PURPOSE: In diabetic macular edema (DME), the correlation between visual acuity (VA) and central subfield thickness (CST) is weak. We hypothesize that fluid volume (FV) in the inner nuclear layer (INL) may correlate more strongly with VA. DESIGN: Retrospective, cross-sectional study. METHODS: One eye each of diabetic patients with DME was included. We measured intraretinal fluid volume that was detected by automated fluid detection algorithm on 3- × 3-mm optical coherence tomography angiogram volume scans. The detected fluid was subdivided into inner FV, bounded by the INL, and outer FV, the fluid between the outer border of INL to the ellipsoid zone. RESULTS: We enrolled 125 patients with DME (60 women; mean age, 61 years). The mean detected inner FV was 0.013 mm3 in 109 eyes (87%). The mean detected outer FV was 0.042 mm3 in 124 eyes (99%). Univariate analysis demonstrated that the VA significantly correlated with the inner FV (P < .0001), whole macular FV (P = .010), and CST (P = .036). Multivariate analysis demonstrated that the inner FV was the only significant factor (ß = -0.41, P = .004). These correlations were consistent when the treatment-naïve group (n = 33) and the eyes without previous laser treatments (n = 93) were analyzed separately. The area under the receiver operating characteristic curve of inner FV for VA of 20/32 or worse was significantly higher than that for CST (0.66 vs 0.54, P = .018). CONCLUSIONS: The inner FV has a stronger association with VA than other OCT biomarkers in DME and may be more clinically useful.

Geographic Atrophy Progression Is Associated With Choriocapillaris Flow Deficits Measured With Optical Coherence Tomographic Angiography.

Purpose: The purpose of this study was to assess the associations between baseline choriocapillaris (CC) flow deficits and geographic atrophy (GA) progression. Methods: In this prospective cohort study, patients with GA underwent 3 × 3-mm macular spectral-domain optical coherence tomographic angiography (OCTA) at baseline and follow-up visits. Annual GA enlargement rate was defined as change of square root of GA area in 12 months. Shadow areas due to iris, media opacity, retinal vessels, and drusen were excluded. CC vessel density (CC-VD) in non-GA areas was measured using a validated machine-learning-based algorithm. Low perfusion area (LPA) was defined as capillary density below the 0.1 percentile threshold of the same location of 40 normal healthy control eye. Focal perfusion loss (FPL) was defined as percentage of CC loss within LPA compared with normal controls. Results: Ten patients with GA were enrolled and followed for 26 months on average. At baseline, the mean GA area was 0.84 ± 0.70 mm2. The mean CC-VD was 44.5 ± 15.2%, the mean LPA was 4.29 ± 2.6 mm2, and the mean FPL was 50.4 ± 28.2%. The annual GA enlargement rate was significantly associated with baseline CC-VD (r = -0.816, P = 0.004), LPA (r = 0.809, P = 0.005), and FPL (r = 0.800, P = 0.005), but not with age (r = 0.008, P = 0.98) and GA area (r = -0.362, P = 0.30). Conclusions: Baseline CC flow deficits were significantly associated with a faster GA enlargement over the course of 1 year, suggesting the choriocapillaris perfusion outside of a GA area may play a role in GA progression.

The effect of retaining intact posterior capsule in congenital cataract surgery in children aged 4-8 years.

BACKGROUND: The present study sought to observe the effect of retaining intact posterior capsule in congenital cataract surgery in children aged 4-8 years. METHODS: This is a retrospective case control study. Seventy-seven children (130 eyes) aged from 4 to 8 years who underwent cataract surgery were divided into two groups. In Group A, 50 eyes underwent phacoemulsification, intraocular lens implantation and posterior capsule capsulotomy combined with anterior vitrectomy. In Group B, 80 eyes underwent cataract phacoemulsification and intraocular lens implantation. The postoperative visual acuity and the rate of complications were compared. RESULTS: In all patients, cataract surgeries were performed evenly without intraoperative complications. The follow-up time ranged from 6 months to 42 months. No apparent visual axis opacity was detected in group A during the follow-up. By the last visit, apparent visual axis opacity was detected in 31 eyes (38.75%) in group B. Among them, 9 eyes (29.03%) with mild posterior capsule opacification (PCO) were treated with Nd:YAG laser, 3 eyes (9.68%) with thick proliferative membranes were treated with posterior capsule capsulotomy combined with anterior vitrectomy and proliferative membranes in 19 eyes (61.29%) were completely aspired and the posterior capsule was retained. During follow-up, only 2 (6.45%) eyes had PCO recurrence and were treated with Nd:YAG laser. The visual acuity was significantly higher than that before surgery in all patients. CONCLUSIONS: For older children, the incidence of PCO will be low even if intact posterior capsule is retained. Either Nd:YAG laser or surgical treatment for PCO will be able to maintain good vision.

Comparison of Central Macular Fluid Volume With Central Subfield Thickness in Patients With Diabetic Macular Edema Using Optical Coherence Tomography Angiography.

IMPORTANCE: Diabetic macular edema (DME) is the predominant cause of visual impairment in patients with type 1 or 2 diabetes. Automated fluid volume measurements using optical coherence tomography (OCT) may improve the diagnostic accuracy of DME screening. OBJECTIVE: To assess the diagnostic accuracy of an automated central macular fluid volume (CMFV) quantification using OCT for DME. DESIGN, SETTING, AND PARTICIPANTS: A cross-sectional observational study was conducted at a tertiary academic center among 215 patients with diabetes (1 eye each) enrolled from January 26, 2015, to December 23, 2019. All participants underwent comprehensive examinations, 6 × 6-mm macular structural OCT horizontal raster scans, and 6 × 6-mm macular OCT angiography volumetric scans. From January 1 to March 30, 2020, 2 retinal specialists reviewed the structural OCT scans independently and diagnosed DME if intraretinal or subretinal fluid was present. Diabetic macular edema was considered center involved if fluid was present within the central fovea (central 1-mm circle). A third retinal specialist arbitrated any discrepancy. The mean central subfield thickness (CST) within the central fovea was measured on structural OCT horizontal raster scans. A deep learning algorithm automatically quantified fluid volumes on 6 × 6-mm OCT angiography volumetric scans and within the central foveas (CMFV). MAIN OUTCOMES AND MEASURES: The area under the receiver operating characteristic curve (AUROC) and the sensitivity and specificity of CST and CMFV for DME diagnosis. RESULTS: We enrolled 1 eye each of 215 patients with diabetes (117 women [54.4%]; mean [SD] age, 59.6 [12.4] years). Diabetic macular edema was present in 136 eyes; 93 cases of DME were center involved. The AUROC of CMFV for diagnosis of center-involved DME (0.907 [95% CI, 0.861-0.954]) was greater than the AUROC of CST (0.832 [95% CI, 0.775-0.889]; P = .02). With the specificity set at 95%, the sensitivity of CMFV for detection of center-involved DME (78.5% [95% CI, 68.8%-86.3%]) was higher than that of CST (53.8% [95% CI, 43.1%-64.2%]; P = .002). Center-involved DME cases not detected by CST but detected by CMFV were associated with a thinner CST (290.8 µm [95% CI, 282.3-299.3 µm] vs 369.4 µm [95% CI, 347.1-391.7 µm]; P < .001), higher proportion of previous macular laser treatment (11 of 28 [39.3%; 95% CI, 21.5%-59.4%] vs 12 of 65 [18.5%; 95% CI, 9.9%-30.0%]; P = .03), and female sex (20 of 28 [71.4%; 95% CI, 51.3%-86.8%] vs 31 of 65 [47.7%; 95% CI, 35.1%-60.5%]; P = .04). CONCLUSIONS AND RELEVANCE: These findings suggest that an automated CMFV is a more accurate diagnostic biomarker than CST for DME and may improve screening for DME.

Optical Coherence Tomography Angiography Avascular Area Association With 1-Year Treatment Requirement and Disease Progression in Diabetic Retinopathy.

PURPOSE: To assess the association between optical coherence tomography angiography (OCTA)-quantified avascular areas (AAs) and diabetic retinopathy (DR) severity, progression, and treatment requirement in the following year. DESIGN: Prospective cohort study. METHODS: We recruited patients with diabetes from a tertiary academic retina practice and obtained 3-mm × 3-mm macular OCTA scans with the AngioVue system and standard 7-field color photographs at baseline and at a 1-year follow-up visit. A masked grader determined the severity of DR from the color photographs using the Early Treatment of Diabetic Retinopathy scale. A custom algorithm detected extrafoveal AA (EAA) excluding the central 1-mm circle in projection-resolved superficial vascular complex (SVC), intermediate capillary plexus (ICP), and deep capillary plexus (DCP). RESULTS: Of 138 patients, 92 (41 men, ranging in age from 26-84 years [mean 59.4 years]) completed 1 year of follow-up. At baseline, EAAs for SVC, ICP, and DCP were all significantly correlated with retinopathy severity (P < .0001). DCP EAA was significantly associated with worse visual acuity (r = -0.24, P = .02), but SVC and ICP EAA were not. At 1 year, 11 eyes progressed in severity by at least 1 step. Multivariate logistic regression analysis demonstrated the progression was significantly associated with baseline SVC EAA (odds ratio = 8.73, P = .04). During the follow-up period, 33 eyes underwent treatment. Multivariate analysis showed that treatment requirement was significantly associated with baseline DCP EAA (odds ratio = 3.39, P = .002). No baseline metric was associated with vision loss at 1 year. CONCLUSIONS: EAAs detected by OCTA in diabetic eyes are significantly associated with baseline DR severity, disease progression, and treatment requirement over 1 year.

Prevalence and Causes of Visual Impairment and Blindness among Adult Chinese in Hong Kong - The Hong Kong Eye Study.

PURPOSE: To investigate the prevalence, associations, and causes of visual impairment and blindness in the adult population of Hong Kong. METHODS: This cross-sectional population-based study included 2018 (870, 43% male) randomly selected adults with a mean age 52 ± 16 years (range 18-90 years) in Hong Kong. Each participant underwent comprehensive ophthalmic examinations. Presenting visual acuity (PVA) and best-corrected visual acuity (BCVA) of each eye was recorded. Prevalence of visual impairment and blindness was calculated using both World Health Organization (WHO) and United States (US) definitions, based on BCVA and PVA. RESULTS: Visual acuity measurements were available for 1952 (96.8%) participants. The prevalence of visual impairment, based on BCVA value, using WHO and US definition, was 1.0 ± 0.1% and 2.7 ± 0.4%, respectively. The prevalence of visual impairment, based on PVA value, was 5.1 ± 0.5% and 14.0 ± 0.8%, using WHO and US definition, respectively. Multivariate analysis demonstrated the presence of visual impairment (PVA, WHO definition) increased significantly with older age (odds ratio 1.039, P < .001) and thinner central cornea thickness (odds ratio 0.994, P = .014), but not significantly associated with other socioeconomic, systemic or ocular parameters after adjusting for age and central corneal thickness. Under-correction of refractive error was the most common reason for presenting visual impairment. Causes of impaired BCVA were cataract (37%), age-related macular degeneration (26%), diabetic macular edema (11%), glaucoma (11%), epiretinal membrane (5%), and unknown (11%). CONCLUSION: The prevalence of visual impairment in Hong Kong increased significantly with older age and thinner central corneal thickness. The major causes for impairment were under-correction of refractive error, cataract, and age-related macular degeneration.

Detection of Reduced Retinal Vessel Density in Eyes with Geographic Atrophy Secondary to Age-Related Macular Degeneration Using Projection-Resolved Optical Coherence Tomography Angiography.

PURPOSE: To compare retinal vessel density in eyes with geographic atrophy (GA) secondary to age-related macular degeneration (AMD) to age-matched healthy eyes by using projection-resolved optical coherence tomography angiography (PR-OCTA). DESIGN: Prospective cross-sectional study. METHODS: Study participants underwent macular 3- × 3-mm OCTA scans with spectral domain OCTA. Reflectance-compensated retinal vessel densities were calculated on projection-resolved superficial vascular complex (SVC), intermediate capillary plexus (ICP), and deep capillary plexus (DCP). Quantitative analysis using normalized deviation compared the retinal vessel density in GA regions, 500-µm GA rim regions, and non-GA regions to similar macular locations in control eyes. RESULTS: Ten eyes with GA and 10 control eyes were studied. Eyes with GA had significantly lower vessel density in the SVC (54.8 ± 2.4% vs. 60.8 ± 3.1%; P < 0.001), ICP (34.0 ± 1.5% vs. 37.3 ± 1.7%; P = 0.003) and DCP (24.4 ± 2.3% vs. 28.0 ± 2.3%; P < 0.001) than control eyes. Retinal vessel density within the GA region decreased significantly in SVC, ICP, and DCP. Retinal vessel density in the GA rim region decreased in SVC and ICP but not in DCP. The non-GA region did not significantly deviate from normal controls. Eyes with GA had significantly reduced photoreceptor layer thickness; but similar nerve fiber layer, ganglion cell complex, inner nuclear layer, and outer plexiform layer thickness. CONCLUSIONS: Eyes with GA have reduced retinal vessel density in SVC, ICP, and DCP compared to those in controls. Loss is greatest within regions of GA. Vessel density may be more sensitive than retinal layer thickness measurement in the detection of inner retinal change in eyes with GA.

DETECTION OF CLINICALLY UNSUSPECTED RETINAL NEOVASCULARIZATION WITH WIDE-FIELD OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY.

PURPOSE: To evaluate wide-field optical coherence tomography angiography (OCTA) for detection of clinically unsuspected neovascularization (NV) in diabetic retinopathy (DR). METHODS: This prospective observational single-center study included adult patients with a clinical diagnosis of nonproliferative DR. Participants underwent a clinical examination, standard 7-field color photography, and OCTA with commercial and prototype swept-source devices. The wide-field OCTA was achieved by montaging five 6 × 10-mm scans from a prototype device into a 25 × 10-mm image and three 6 × 6-mm scans from a commercial device into a 15 × 6-mm image. A masked grader determined the retinopathy severity from color photographs. Two trained readers examined conventional and wide-field OCTA images for the presence of NV. RESULTS: Of 27 participants, photographic grading found 13 mild, 7 moderate, and 7 severe nonproliferative DR. Conventional 6 × 6-mm OCTA detected NV in 2 eyes (7%) and none with 3 × 3-mm scans. Both prototype and commercial wide-field OCTA detected NV in two additional eyes. The mean area of NV was 0.38 mm (range 0.17-0.54 mm). All eyes with OCTA-detected NV were photographically graded as severe nonproliferative DR. CONCLUSION: Wide-field OCTA can detect small NV not seen on clinical examination or color photographs and may improve the clinical evaluation of DR.

Macular Vessel Density Measured With Optical Coherence Tomography Angiography and Its Associations in a Large Population-Based Study.

Purpose: We investigate macular perfusion and the systemic and ocular associations in a population-based setting. Methods: In this cross-sectional study, 2018 adults residing in Hong Kong underwent detailed ophthalmic examinations after consenting to participate. Macular perfusion was measured with optical coherence tomography angiography (OCTA) using the split-spectrum amplitude decorrelation angiography algorithm. The parafoveal flow index and vessel area density were quantified using automated custom-built software. Results: Of the 2018 participants, the OCTA measurements were available for 1940, and 1631 (84.1%) had good quality scans. The right eyes of these 1631 participants (43.1% men) were included for final analysis. Mean age was 49.8 years (range, 18-92 years). Mean global macular vessel density was 47.3% and 55.1% for the superficial and deep retinal layers, respectively. In multivariate analysis, lower superficial vessel density remained significantly associated with lower signal strength index (SSI; P < 0.001, standardized ß = 0.607) and male sex (P < 0.001, ß = 0.162), and borderline associated with older age (P = 0.09, ß = -0.045) and longer axial length (AL; P = 0.09, ß = -0.037), while lower deep layer vessel density was significantly associated with lower SSI (P < 0.001, standardized ß = 0.667), longer AL (P < 0.001, ß = -0.097), and higher creatinine (P < 0.001, ß = -0.072). Conclusions: This large population-based study provided normative OCTA data of macular vessel density and demonstrated that a lower superficial retinal vessel density was significantly associated with lower SSI and male sex, while a lower deep layer retinal vessel density was significantly associated with lower SSI, longer AL, and higher level of creatinine. These associations must be considered when interpreting clinical quantitative OCTA data.

Silencing of GAS5 Alleviates Glaucoma in Rat Models by Reducing Retinal Ganglion Cell Apoptosis.

Retinal ganglion cells (RGCs) play a key role in the pathogenesis and development of glaucoma. The present study aims to investigate the underlying mechanism of long noncoding RNA growth arrest-specific transcript 5 (GAS5) in glaucoma development through regulating the apoptosis of RGCs. Rat models of chronic glaucoma were successfully established by translimbal laser photocoagulation. Retinal tissues were collected to determine the density of RGCs through Toluidine blue staining. The overexpression vector or short hairpin RNA for GAS5 or enhancer of zeste homolog 2 (EZH2) was transfected into RGCs after in vitro pressurization culture to examine the function of GAS5 in RGC apoptosis. The involvement of EZH2 and ATP-binding cassette transporter A1 (ABCA1) was further identified. Cell apoptosis after laser treatment and transfection was assessed by flow cytometry. We found abundant GAS5 expression and a reduction in RGC density in the retinal tissues of glaucoma rats. Silencing of GAS5 led to increased EZH2 expression and decreased ABCA1 expression in RGCs. In addition, upregulation of EZH2 promoted trimethylation of lysine 27 on histone H3, thereby suppressing ABCA1 expression and eventually leading to the inhibition of RGC apoptosis. These findings provide further understanding of the function of GAS5 in RGC apoptosis. We conclude that downregulation of GAS5 could help relieve glaucoma symptoms. GAS5 is therefore a promising target for developing novel therapeutic approaches for treating patients with glaucoma.

Genetic factors for idiopathic choroidal neovascularization.

Objective: The aim of this study was to investigate genetic factors associated with idiopathic choroidal neovascularization (ICNV). Methods: We conducted a case-control study including 69 cases with ICNV and 114 controls who underwent cataract surgery. Single nucleotide polymorphisms (SNPs) from genes reported to be related to AMD, CNV and uveitis were selected for this study. Results: In an univariate analysis, the rs669676 SNP located in the COL8A1 gene was associated with the proportion of people who has idiopathic CNV ( X2 = 9.3453, corrected p-value = 0.1). For the rs669676 SNP, minor allele homozygotes, in the dominant model of genotype analysis (GG versus AA-GA), it showed significant differences in the ICNV group vs controls (p = .01, OR = 1.219 (95%CI: 1.04-1.429)). Conclusions: The rs669676 SNP located in the COL8A1 gene may contribute to a genetic susceptibility for ICNV.

POSTERIOR FUNDUS HEMORRHAGES: Frequency and Associated Factors: The Beijing Eye Study.

PURPOSE: To examine frequency and associations of retinal hemorrhages. METHODS: The population-based Beijing Eye Study included 3,468 individuals. Monoscopic fundus photographs were examined for hemorrhages. RESULTS: Retinal hemorrhages were detected in 515 eyes (429 individuals) (prevalence: 7.6%; 95% confidence interval [CI]: 7.0-8.0 per eye; 12.7%; 95% CI: 11.7-13.7 per person). Higher prevalence of retinal hemorrhages was correlated (multivariate analysis) with higher systolic blood pressure (P < 0.001; odds ratio: 1.02; 95% CI: 1.01-1.03), higher prevalence of diabetic retinopathy (P < 0.001; odds ratio: 121; 95% CI: 61-240), and higher prevalence of retinal vein occlusions (P < 0.001; odds ratio: 27; 95% CI: 17-42). Retinal hemorrhages were due to diabetic retinopathy (189 [36.7%] eyes), retinal vein occlusions (n = 65 [12.6%]), posterior vitreous detachment (n = 23 [4.5%]), glaucoma (n = 14 [2.7%]), exudative age-related macular degeneration (n = 8 [1.6%]), hypertensive retinopathy (n = 10 [1.9%]), and exudative myopic maculopathy (n = 1 [0.2%]). Retinal hemorrhages without evident ocular cause ("NOH") were detected in 204 (3.0%) eyes (or 39.6% of all retinal hemorrhages). Higher prevalence of NOHs was correlated with higher systolic blood pressure (P < 0.001; odds ratio: 1.02; 95% CI: 1.01-1.03) after adjusting for blood glucose concentration and prevalence of cortical cataract. CONCLUSION: In a population-based recruited cohort of individuals aged 50+ years, prevalence of any fundus hemorrhage was about 8% per eye and 13% per individual. Approximately 60% of the hemorrhages were due to ocular reasons, mainly diabetic retinopathy, retinal vein occlusions, and posterior vitreous detachment, whereas 40% of the bleedings were not evidently associated with ophthalmologic causes but strongly with elevated systolic blood pressure.

ANATOMICAL AND FUNCTIONAL TESTING IN DIABETIC PATIENTS WITHOUT RETINOPATHY: Results of Optical Coherence Tomography Angiography and Visual Acuity Under Varying Contrast and Luminance Conditions.

PURPOSE: To assess early retinal microvascular and functional changes in diabetic patients without clinical evidence of diabetic retinopathy with optical coherence tomography angiography and central visual analyzer. METHODS: This was an observational case-control study of diabetic patients without diabetic retinopathy and nondiabetic controls. Patients underwent optical coherence tomography angiography imaging and visual acuity testing using the central visual analyzer. The foveal avascular zone area and the capillary density in the superficial and deep capillary plexuses were measured manually by a masked grader. RESULTS: Sixty eyes from 35 diabetic patients were included in the study group, and 45 eyes from 31 nondiabetic patients were included in the control group. The foveal avascular zone area was not significantly different between the diabetic group and controls (both P > 0.05). The mean capillary density in the deep capillary plexus was significantly lower in diabetic eyes compared with control eyes (P = 0.04). The mean visual acuity in all central visual analyzer modules was significantly decreased in diabetic patients compared with controls (all P < 0.05). CONCLUSION: Optical coherence tomography angiography was able to detect retinal microvascular changes in the deep capillary plexus, and the central visual analyzer showed signs of decreased visual acuity under conditions simulating suboptimal contrast and glare in diabetic patients without diabetic retinopathy.