Mean Foveal Avascular Zone Area Research Articles

Internal Limiting Membrane Peeling for Large Macular Holes Induces Only Structural Remodeling without Functional Impairment Over 12 Years

To evaluate the very long-term functional and structural outcomes of internal limiting membrane (ILM) peeling for full-thickness macular holes (FTMH). Observational case series nested within a multicenter, randomized, controlled clinical trial (RCT) (ClinicalTrials.gov: NCT00190190). Patients who underwent vitrectomy with or without ILM peeling for an idiopathic large FTMH in a tertiary ophthalmology center, with a minimum follow-up of 10 years after surgery. Review of charts, spectral-domain OCT (SD-OCT) scans, OCT angiography (OCTA) scans, and microperimetry of patients originally enrolled in the RCT. Primary outcome was functional assessment in both groups (ILM peeling or not) including the retinal sensitivity (RS), distance and near best-corrected visual acuity (BCVA), and number of eyes achieving ≥0.3 logarithm of the minimum angle of resolution >10 years after surgery. Secondary outcomes were structural assessment in the entire 3× 3-mm and 6× 6-mm areas, and regionally in the different areas of the ETDRS grid: OCT and OCTA biomarkers in both groups and fellow eyes. Thirteen eyes of 13 patients with a mean follow-up of 12 ± 0.73 years were included. The mean RS and BCVA, or visual improvement did not differ between ILM peeling (n= 8) and no peeling (n= 5) (all P > 0.05). The dissociated optic nerve fiber layers on en face OCT were only observed in eyes with ILM peeling, predominantly in temporal parafoveal (20%) and perifoveal (19%) rings. The mean total retinal thickness and inner retinal thickness in the parafoveal ring were significantly lower in peeled eyes (309 ± 11 μm and 94 ± 9 μm respectively) versus nonpeeled eyes (330 ± 21 μm and 108 ± 11 μm respectively; P= 0.037 and P= 0.040), without significant difference in ganglion cell or retinal nerve fiber layers. Accordingly, the mean superficial capillary plexus density in the parafoveal ring was significantly lower in eyes with peeling versus without (39.65 ± 3.76 % versus 47.22 ± 4.00; P= 0.005). The mean foveal avascular zone area was smaller in eyes with peeling versus without (0.24 ± 0.05 mm2 vs. 0.42 ± 0.13 mm2, respectively, P= 0.005). Despite persistent structural changes especially in the parafoveal ring, ILM peeling for idiopathic large FTMH did not seem to impact long-term RS or BCVA over 12 years. Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Investigation of factors that may affect the foveal avascular zone: An optical coherence tomography angiography study

SIGNIFICANCE An understanding of factors that affect the foveal avascular zone (FAZ) in healthy eyes may aid in the early identification of patients at risk of retinal pathology, thereby allowing better management and preventive measures to be implemented. PURPOSE The size and shape of the FAZ can change due to retinal diseases associated with oxidative stress, including diabetic retinopathy, glaucoma, and macular degeneration. This study aimed to assess the relationship, if any, between factors that may affect the superficial FAZ (i.e., vessel density, vessel perfusion, overweight/obesity) and possible links with macular pigment optical density in young, healthy participants. METHODS One hundred thirty-nine participants aged 18 to 35 years were recruited to this cross-sectional study. The superficial FAZ area, foveal vascularity, and central macular thickness (CMT) were assessed using the Cirrus 5000. Health parameters, body mass index, trunk fat %, and macular pigment were analyzed to determine possible associations with the superficial FAZ. RESULTS Mean FAZ area was 0.23 ± 0.08 mm2. Females had a significantly larger mean FAZ area than males (p=0.002). The FAZ area was positively correlated with body mass index (Pearson's r = 0.189, p=0.026). Significant correlates of the FAZ area in the multivariate model included vessel perfusion (central), CMT, and trunk fat %, collectively explaining 65.1% of the overall variability. CONCLUSIONS Study findings suggest that reduced vessel perfusion, thinner CMT, and higher trunk fat % are plausible predictors of a larger FAZ area in healthy Caucasian adults. Low macular pigment optical density was, however, not associated with increased FAZ size in young healthy eyes. Noninvasive optical coherence tomography angiography testing, in association with these predictors, may aid in the early detection and monitoring of retinal diseases associated with oxidative stress.

Evaluation of Optical Coherence Tomography Angiography in Degenerative and Tractional Lamellar Macular Hole.

This study aims to evaluate the optical coherence tomography angiography (OCTA) findings in cases with degenerative and tractional lamellar macular holes (LMH). Two subtypes of LMH cases were included. Seventeen patients had the degenerative subtype, whereas 18 patients had the tractional subtype of LMH. Twenty healthy individuals were enrolled as the control group. The foveal avascular zone (FAZ) and retinal vascular densities in the superficial, deep capillary, and choriocapillary plexuses were analyzed and compared with fellow eyes and healthy controls using OCTA. The mean FAZ area was wider in the degenerative subtype (0.33 ± 0.14 mm2) compared to the tractional subtype (0.24 ± 0.10 mm2) (p=0.04) and control eyes (0.26 ± 0.10 mm2) (p=0.03). Foveal vessel densities in the superficial and deep capillary plexuses were lower in the degenerative group than in the tractional group, (21.7 ± 9.8% vs. 26.8 ± 6.9%, p=0.01 and 28.5 ± 5.1% vs. 36.9 ± 6.2%, p=0.01). Choriocapillary vascular density in the parafoveal area was also lower in degenerative lamellar macular holes compared to the tractional group (60.4 ± 4.7% vs. 63.7 ± 3.9%, p=0.03). Compared to control eyes, eyes with degenerative and tractional LMH showed lower vessel densities in the parafoveal and perifoveal areas of the SCP, DCP, and all layers of CC (p < 0.05). In the foveal area, the LMH groups showed higher foveal vascular density (FVD) in the SCP than control eyes, while in the DCP, FVD was lower in the degenerative LMH eyes relative to the other groups. The finding of microvascular changes between degenerative and tractional LMH subtypes highlights their distinct pathologies and supports recent changes in the classification and terminology of this macular condition.

A cross-sectional study of macular displacement after macular hole surgery with ILM peeling in patients with idiopathic macular hole.

To examine the retinal displacement and change in mean superficial foveal avascular zone (FAZ) after successful closure of macular hole (MH) with vitrectomy with internal limiting membrane peeling (ILM) and gas tamponade. A total of 45 patients with idiopathic MH who underwent 23G pars plana vitrectomy with ILM peeling and tamponade with 20% SF6/14% C3F8 were included. Follow-up visits were performed at 2, 4, and 8 weeks. OCT and OCT-A scans were performed along with detailed ocular examination. Distance between optic disc and an easily identifiable vascular bifurcation nasal and temporal to fovea, FAZ, was noted. Chi-square test (categorical data) and Mann-Whitney U test and t tests for other parameters were performed for statistical analysis. The mean displacement (µm) of an easily identifiable vascular bifurcation in the nasal quadrant was 96.58 ± 36.55 at 8 weeks and in the temporal quadrant was 273.07 ± 85.51 at 8 weeks. The change was statistically significant in the temporal quadrant (P = <0.001). The mean BCVA changed from a minimum of 0.08 at the preoperative timepoint to a maximum of 0.23 at 8 weeks (P = <0.001). The mean FAZ area (mm²) decreased from a maximum of 0.37 at the preoperative timepoint to a minimum of 0.19 at 8 weeks (p = <0.001). The retina in the temporal quadrant is displaced significantly more than nasal quadrant after successful closure of macular hole. The mean superficial FAZ also decreases suggesting a centripetal movement of the foveal tissue postoperatively.

Comparison of retinochoroidal and optic nerve head microvascular circulation between HIV-positive patients and healthy subjects using optical coherence tomography angiography

To evaluate the retinal, choroidal, and optic disc head microvascular circulation in human immunodeficiency virus (HIV)-infected individuals without retinopathy receiving highly active antiretroviral therapy (HAART) using swept-source optical coherence tomography angiography (SS-OCTA). This cross-sectional study included 100eyes of 100patients with HIV infection but no HIV-related ocular disease and 108 eyes of 108 age- and sex-matched healthy subjects as the control group. SS-OCTA was used to assess foveal avascular zone (FAZ) area, retinal nerve fiber layer thickness (RNFL), choriocapillaris (CC) flow area, outer retinal (OR) thickness, radial peripapillary capillary (RPC) vessel density (VD), ONH VD, and choroidal thickness. No statistically significant difference was found between the two groups except in the foveal VD of the deep capillary plexus (DCP). The foveal VD of the DCP was lower in the HIV-positive group (P=0.011). The mean FAZ area (mm2), perimeter (mm), and CC flow area (mm) values were higher in the HIV-positive group at statistically significant levels (P=0.021, P=0.02, and P=0.039, respectively). However, no statistically significant differences were found between the two groups concerning the OR flow area, subfoveal choroidal thickness, or the VDs of the RPC or ONH. This is the first study in the literature to evaluate the microvascular circulation of the ONH in HIV-positive patients. Although retinal and choroidal microvascular circulation decreased in HIV-positive patients receiving HAART treatment, we found no effect on the microvascular circulation of the ONH or RPC microvascular circulation. Our findings suggest that retinochoroidal microvascular circulation is affected in HIV-positive patients over time.

Comparative study between fundus fluorescein angiography and optical coherence tomography angiography in evaluation of diabetic maculopathy

Background Diabetic maculopathy is a serious consequence of diabetic retinopathy (DR) that greatly affects the visual acuity. Diabetic macular edema (DME) and diabetic macular ischemia (DMI) are major causes of vision affection in diabetic patients. Purpose The aim of this study was to compare fluorescein angiography (FA) and optical coherence tomography angiography (OCTA) in evaluation of diabetic maculopathy. Patients and methods This comparative cross-sectional study was performed on 87 eyes of 54 patients with type I or type II diabetes, older than 18 years old with any diabetic retinal changes, and 108 eyes of 54 control subjects. An ocular examination was performed as well as color fundus photography, FA, and OCTA. Investigations were done on the same day. FA and OCTA findings were summarized and compared. Results The mean age of the patients was 59.4±8.5 years. OCTA was statistically significantly superior to FA in diagnosing DMI. The foveal avascular zone (FAZ) was ischemic (enlarged) in 74 (85.06%) eyes by OCTA compared with only 46 (52.87%) eyes by FA, with a statistically significant difference (P = 0.001). In addition, OCTA detected microaneurysms significantly more than FA (P = 0.001). The mean FAZ area of the control eyes by OCTA was significantly less than in the ischemic eyes (U = 56.602, P &lt; 0.001), while the superficial capillary plexus (SCP) vascular density (VD) and the deep capillary plexus (DCP) VD in the control eyes was statistically significantly higher than in the ischemic eyes (U = 36.984, P &lt; 0.001, and U = 35.955, P &lt; 0.001, respectively). FA showed diffuse leakage (edema) at the macula as the most common pattern of DME that was detected in 37.9% of the eyes followed by focal macular leakage in 18.4% of the eyes and cystoid leakage in 8% of the eyes while 35.5% of the eyes showed no macular edema. Conclusion OCTA is a cornerstone in DMI diagnosis both qualitatively and quantitatively. In addition, it is essential in evaluating the deep retinal vasculature, while FA is essential in diabetic retinopathy grading and in the diagnosis of DME in a qualitative manner. Both investigations are complementary to each other in diabetic maculopathy evaluation.

Optical coherence tomography angiography in birdshot chorioretinopathy.

To describe the retinal vascular changes in birdshot chorioretinopathy (BSCR) using optical coherence tomography angiography (OCTA) and to compare them with changes in macular thickness. In this multicenter study, patients with a diagnosis of BSCR and a positive HLA-A29 underwent fluorescein angiography, spectral domain optical coherence tomography (SD-OCT), and OCTA. The foveal avascular zone (FAZ) and the area of capillary non-perfusion were manually measured by two examiners in fluorescein angiography (FA) and 3 × 3-mm OCTA images of the superficial retinal layer. These measurements were compared to central retinal thickness. To calculate normal capillary density, we collected data from 22 controls who had OCTA performed on one visit only. A total of 44 eyes with BSCR were enrolled. The mean automated parafoveal superficial capillary density in BSCR eyes was 0.47 ± 0.03. The differences between the foveal capillary density of BSCR patients and healthy subjects were statistically significant (P < 0.001). The mean area of FAZ manually measured on the 3 × 3 mm unsegmented OCTA images was larger in eyes with BSCR (1.34 ± 0.41 mm2; P < 0.0001). Measurement of FAZ area showed good interobserver (κ 0.88) and intraobserver repeatability (κ 0.79) on OCTA images. The intraclass correlation coefficient for FAZ measurements on FA between the two observers was 0.48. The OCT retinal thickness maps of all BSCR eyes demonstrated statistically significant thinning compared to those of control subjects (P < 0.01). Our study demonstrates the potential contribution of OCTA as a new non-invasive imaging technology that monitors disease activity in BSCR patients.

Evaluation of childhood developing via optical coherence tomography-angiography in Qamdo, Tibet, China: A prospective cross-sectional, school-based study.

Optical coherence tomography angiography (OCTA) is a new and reliable machine used to evaluate retinal structure and macular perfusion in children. The use of OCTA under bad condition such as high altitude, low atmospheric oxygen, and low humidity, in children is rarely. To quantify the macular micro-vasculature in healthy children of various ages using OCTA in Qamdo. Design: Prospective cross-sectional, school-based study. Three hundred and forty-seven normal students from 9 schools in 4 different areas in Qamdo were included. OCTA was performed on a 3 mm × 3 mm area centered on the macular region and macular cube 512 × 128 showed details in macular. Early treatment of diabetic retinopathy study Vessel Flow Density (VD) of the macular central vascular plexus density (CVD), inner vascular plexus density (IVD), full vascular plexus density (FVD), and the size of the foveal avascular zone (FAZ) were measured. All these results corrected by t/s = 3.382 × 0.01306 × (axial length-1.82). The differences were compared among various ages, sexes and living environments. The mean FAZ area in all eyes was 0.27 mm2 ± 0.12 mm2. The mean foveal thickness (MFT) in the macular cube was 227.64 μm ± 23.51 μm. Compared with girls, boys had a lager FAZ (P = 0.0029). Among the different age groups, MFT (P < 0.001) and FVD (P < 0.0001), IVD (P < 0.0001), and CVD (P = 0.0050) increased with age. FAZ areas were not correlated with age (P = 0.8853) or others (MFT, area). OCTA can use to evaluate macular perfusion in children. Our data bridge the gap between structural OCT and perfusion density in children in high altitude. Even though these were not a longitudinal study, it may provide us with hints about retina development during puberty and clinical implications of OCTA in children.

Retinal and choroidal microvasculature in early and three months post COVID-19: A case-control study

To compare the retinal vascular density (VD), choroidal vascularity index (CVI), and choroidal thickness (CHT) between patients infected with COVID-19 and healthy subjects using non-invasive optical coherence tomography angiography (OCTA) and enhanced depth imaging OCT (EDI-OCT) technique.This case-control study was carried out on patients with COVID-19 and healthy controls. Patients’ data were acquired immediately after active infection and three months later. The diagnosis was based on clinical symptoms and a positive PCR test. VDs in superficial and deep capillary plexuses (SCP and DCP) and CHT and CVI were measured and compared between groups. A total of 160 eyes from 80 patients (55% female, mean age 51 ± 13 years) and 80 controls (55% female, mean age 49 ± 12 years) were enrolled. In acute phase infection, the mean foveal avascular zone (FAZ) area was 0.28 ± 0.06 mm2 and 0.22 ± 0.05 mm2 in patient and control groups, respectively (P < 0.001). CVI was 61.06 ± 2.59 µm and 72.28 ± 3.84 µm in patients and control groups, respectively (P < 0.001). After three months, the mean FAZ area was 0.28 ± 0.06 mm2 and 0.23 ± 0.05 mm2 in the patient and control groups, respectively (P < 0.001). CVI was 60.93 ± 2.11 µm and 72.46 ± 3.80 µm in patients and control groups, respectively (P < 0.001). Subfoveal CHT was not significantly different between groups (P = 0.69). SCP and DCP VDs were significantly less in the patients’ group (P < 0.001). In the patients’ group, the VDs in the DCP of the whole images and parafoveal DCP (P < 0.001) were reduced significantly after three months in comparison to the acute phase, while the FAZ area, subfoveal CHT, and CVI were not significantly different.COVID-19 infection may be associated with acute and long-term changes of VDs in the retinal and choroidal vasculature without significant effect on the subfoveal CHT.

Optical coherence tomography-based assessment of macular vessel density, retinal layer metrics and sub-foveal choroidal thickness in COVID-19 recovered patients.

The primary objective of the study was to assess the macular retinal vessel density, subfoveal choroidal thickness, and retinal layer metrics by optical coherence tomography angiography (OCTA), enhanced-depth imaging optical coherence tomography (EDI-OCT), and spectral domain optical coherence tomography (SD-OCT), respectively, in recovered COVID-19 patients and its comparison with the same in control subjects. The secondary objective was to evaluate differences in OCTA parameters in relation with the severity of COVID-19 disease and administration of corticosteroids. A case-control study was performed that included patients who had recovered from COVID-19 and age-matched healthy controls. Complete ocular examination including OCTA, SD-OCT, and EDI-OCT were performed three months following the diagnosis. Three hundred sixty eyes of 180 subjects were enrolled between the two groups. A decreased mean foveal avascular zone area in both superficial capillary plexuses (P = 0.03) and deep capillary plexuses (P < 0.01), reduced average ganglion cell layer-inner plexiform layer thickness (P = 0.04), and increased subfoveal choroidal thickness (P < 0.001) were observed among cases in comparison to the control group. A significant correlation was found between sectoral macular vessel density in relation to disease severity and a decrease in vessel density with greater severity of the disease. OCTA detected retinal microvascular alterations following SARS-CoV-2 infection in subjects with the absence of any clinical ocular manifestation or systemic thrombotic events. These parameters could be used to help identify patients with a higher incidence of systemic thromboembolism on longer follow-ups and identify the impact of corticosteroids on retinal architecture.

Optical Coherence Tomography Angiography in Diabetic Macular Edema Treated with Intravitreal Aflibercept: A 48-Week Observational Study (the DOCTA Study)

Introduction: Central vision loss due to diabetic macular edema (DME) is related to the macular edema itself but also, in some cases, to alterations of the foveal avascular zone (FAZ). The aim of this trial was to study changes in macular vessels in eyes with DME treated with aflibercept using optical coherence tomography angiography (OCTA). Methods: This was a longitudinal, prospective, noncontrolled, single-arm study. The primary objective was the quantitative assessment of macular vessels over time in patients with DME treated with intravitreal aflibercept during a 48-week follow-up using OCTA. Results: Twenty-six DME eyes from 26 patients were included (mean age, 64.6 years; women, 53.8%; prior anti-VEGF treatment, 46.1%). Each eye received a mean (SD) of 7.2 (2.2) injections. The following parameters of the FAZ did not change during the 48-week follow-up: the mean (SD) FAZ area varied from 0.19 (0.19) mm² at baseline (n = 22) to 0.23 (0.20) mm² at week 48 (n = 15), boundary from 1.54 (1.21) to 2.04 (1.20) mm, and circularity from 0.45 (0.33)% to 0.57 (0.20)%. There was no change in perfusion density and vessel density of the macula in the 3-mm circle. As expected, mean central retinal thickness, macular volume, and visual acuity improved during follow-up. Conclusion: No change in macular perfusion was observed in eyes with DME during a 48-week follow-up after intravitreal injections of aflibercept. Randomized controlled trials using OCT angiography in large populations with extended observation periods are needed to assess changes in macular vessels after intravitreal anti-VEGF treatment.

Association Between Optical Coherence Tomography Angiography Findings and Inner Retinal Thickness in Diabetic Patients.

To investigate the association between optical coherence tomography angiography (OCTA) findings and inner retinal thickness (IRT) in diabetic patients. This retrospective study included 23 eyes of 23 diabetic patients with retinopathy (group 1), 30 eyes of 30 diabetic patients without retinopathy (group 2), and 27 eyes of 27 non-diabetic age-matched controls (group 3). Foveal avascular zone (FAZ) area (mm²), average vessel density (%) in the parafoveal region, and average IRT in the parafoveal region (μm) were calculated using 6x6 mm OCTA images. Correlations between IRT and OCTA findings were analyzed. The mean FAZ area was 0.32±0.11 mm² in group 1, 0.29±0.08 mm² in group 2, and 0.22±0.09 mm² in group 3. There were statistically significant differences between groups 1 and 3 (p&lt;0.001) and between groups 2 and 3 (p=0.001). Average IRT was 108.02±9.42 µm in group 1, 110.12±11.01 µm in group 2, and 114.41±5.21 µm in group 3, with statistically significant differences between groups 1 and 3 (p=0.003) and between groups 2 and 3 (p=0.014). In both group 1 and group 2, average IRT was correlated with FAZ area (r=-0.320 and -0.512, respectively). The inner retina is significantly thinner in diabetic patients with and without retinopathy compared to controls. Quantitative OCTA findings and IRT are correlated in diabetic patients, suggesting that both structures are compromised in patients with diabetes with or without retinopathy. Microvascular changes in FAZ detected by OCTA might precede neurodegenerative changes.

Various configuration types of the foveal avascular zone with related factors in normal Chinese adults with or without myopia assessed by swept-source OCT angiography.

To describe the morphological characteristics of foveal avascular zone (FAZ) in normal Chinese adults with or without myopia by swept-source optical coherence tomography angiography (SS-OCTA) and analyze the possible associated factors. Normal Chinese adults with or without myopia aged between 18 and 60y were recruited into the study. One eye in each individual was randomly selected for scanning using SS-OCTA. FAZ parameters, central retinal thickness (CRT) and central choroidal thickness (CCT) were then analyzed. Correlations between systemic and ocular variables and FAZ parameters were subsequently evaluated. The subgroup analysis based on refractive error was also carried out. In total, 127 eyes out of 127 normal subjects were finally included in the study (mean age 29.5±8.22y, 61 males and 66 females). The pattern of FAZ was variable: round configuration in 28 eyes (22%), quadrilateral configuration in 23 eyes (18%), pentagonal configuration in 20 eyes (16%), oval configuration in 15 eyes (12%), triangular configuration in 6 eyes (5%) and irregular configuration in 35 eyes (28%). The mean area of FAZ was 0.37±0.12 mm2. Females had a larger FAZ (0.41±0.11 mm2 vs 0.32±0.11 mm2) compared with that of males (P<0.01). All myopic individuals showed smaller FAZ area and perimeter compared with that of normal individuals (P<0.01). There was no obvious correlation between age and FAZ. In the univariate regression analysis, both axial length (AL) and refractive error were significantly related to FAZ parameters. However, only CRT showed negative correlation with FAZ in the multivariate regression analysis. The pattern of FAZ configuration in normal Chinese adults with or without myopia is highly variable. Establishing quantitative parameters of FAZ would not only provide details of macular pathophysiology but could possibly contribute as a biomarker in disease staging.

Evaluating the Quantitative Foveal Avascular Zone and Retino-Choroidal Vessel Density Using Optical Coherence Tomography Angiography in a Healthy Indian Population.

Objective: The foveal avascular zone (FAZ) is the round capillary-free zone within the macula and is supplied only by a single-layered parafoveal capillary arcade. This study aimed to evaluate the quantitative FAZ and retino-choroidal vessel density (VD) using optical coherence tomography angiography (OCTA) in a healthy Indian population.Methods: This was a cross-sectional observational study that was conducted for evaluating the quantitative FAZ and retino-choroidal VD of 200 eyes of 100 healthy Indian subjects, including 62 males and 38 females (age range 17-50 years) having the best-corrected visual acuity (BCVA) of logMAR 0 (20/20; 6/6) and spherical equivalent refractive error of not more than 1 D. The subjects were examined using OCTA automated software on spectral-domain OCT (SD-OCT; Nidek RS 3000 Advance 2; Nidek, Inc., Fremont, CA) on a 3 x 3 mm OCTA macular scan centred on the fovea. The FAZ size, perimeter and circularity index, VD in superficial, deep, and outer retina (OR), outer retinal chorio-capillaries (ORCC), chorio-capillaries (CC) and choroid (C) were analysed in the circular and quadrant-segmented zones. A correlation was found between the FAZ size, perimeter and circularity, and VD in retino-choroidal layers, and between BCVA, age, central foveal thickness (CFT) and sub-foveal choroidal thickness (SFCT), and OCTA parameters.Results: The FAZ and surrounding vascular arcades were intact in all eyes, showing either a vertical or horizontal oval-shaped symmetrical formation without gaps, holes or interruption of the capillary network. The mean value of CFT was 237.5±26.0 microns and SFCT was 269.6±53.0 microns. The mean FAZ area was 0.42±0.23 mm2, FAZ perimeter was 3.3±1.0 mm and FAZ circularity index was 0.46±0.1. The mean VD in superficial capillary plexus (SCP) was 23.87±10.66, in deep capillary plexus (DCP) was 16.03±9.90, in OR was 13.22± 12.27, in ORCC was 39.74±14.32, in CC was 37.02±16.43 and in choroid was 37.43±16.76. The increasing order of VD in different retino-choroidal layers was OR<DCP<SCP<CC<C<ORCC. The FAZ area and perimeter had a statistically significant (SS) negative correlation with the VD in SCP, DCP and OR, while the FAZ perimeter additionally had a SS negative correlation with the VD in the choroid. The FAZ circularity had a SS positive correlation with VD in SCP, DCP and OR. There was no SS correlation between the age of subjects and OCTA parameters. The BCVA had a SS correlation with only one parameter, i.e. ORCC foveal (r=-0.15; p=0.03). There was a SS negative correlation between CFT and FAZ area and perimeter, and a SS positive correlation between the CFT and VD in SCP, DCP and OR. There was a SS positive correlation between the SFCT and VD in different layers including SCP, DCP, ORCC, CC and choroid.Conclusions: VD is the highest in the ORCC and lowest in the OR segment. A better VD in SCP, DCP and OR is associated with a reduced FAZ area/FAZ perimeter and an increased FAZ circularity index. A lower VD in the ORCC is associated with worse BCVA. In a healthy subject, a relatively thicker foveal region is likely to have better vascularity of SCP, DCP and OR and a smaller FAZ area/FAZ perimeter. In the absence of diseases, relatively thicker sub-foveal choroid is expected to have better vascularity of SCP, DCP, ORCC, CC and choroid.

Normative Data and Associations of OCT Angiography Measurements of the Macula: The Singapore Malay Eye Study

To describe the normative quantitative parameters of the macular retinal vasculature, as well as their systemic and ocular associations using OCT angiography (OCTA). Population-based, cross-sectional study. Adults aged > 50 years were recruited from the third examination of the population-based Singapore Malay Eye Study. All participants underwent a standardized comprehensive examination and spectral-domain OCTA (Optovue) of the macula. OCT angiography scans that revealed pre-existing retinal disease, revealed macular pathology, and had poor quality were excluded. The normative quantitative vessel densities of the superficial layer, deep layer, and foveal avascular zone (FAZ) were evaluated. Ocular and systemic associations with macular retinal vasculature parameters were also evaluated in a multivariable analysis using linear regression models with generalized estimating equation models. We included 1184 scans (1184 eyes) of 749 participants. The mean macular superficial vessel density (SVD) and deep vessel density (DVD) were 45.1 ± 4.2% (95% confidence interval [CI], 37.8%-51.4%) and 44.4 ± 5.2% (95% CI, 36.9%-53.2%), respectively. The mean SVD and DVD were highest in the superior quadrant (48.7 ± 5.9%) and nasal quadrant (52.7 ± 4.6%), respectively. The mean FAZ area and perimeter were 0.32 ± 0.11 mm2 (95% CI, 0.17-0.51 mm) and 2.14 ± 0.38 mm (95% CI, 1.54-2.75 mm), respectively. In themultivariable regression analysis, female sex was associated with higher SVD (β= 1.25, P ≤ 0.001) and DVD (β= 0.75, P= 0.021). Older age (β=-0.67, P < 0.001) was associated with lower SVD, whereas longer axial length (β=-0.42, P= 0.003) was associated with lower DVD. Female sex, shorter axial length, and worse best-corrected distance visual acuity were associated with a larger FAZ area. No association of a range of systemic parameters with vessel density was found. This study provided normative macular vasculature parameters in an adult Asian population, which may serve as reference values for quantitative interpretation of OCTA data in normal and disease states.

The role of angio-optical coherent tomography in the surgical management of the vitreoretinal interface

Optical coherence tomography angiography (OCT-A) is a noninvasive diagnostic method for three-dimensional visualization of the vascular structures of the retina and choroid. The aim of this study was to evaluate the diagnostic role of OCT-A preoperatively and postoperatively in vitreoretinal interface (VRI) pathologies, by determining the size of the foveal avascular zone (FAZ) in the superficial (SCP) and deep capillary plexus (DCP) and to compare these parameters with control (healthy) eyes. Medical records of 19 patients were prospectively analyzed: nine with a full-thickness macular hole (FTMH) and ten with an idiopathic epiretinal membrane (ERM). All participants underwent unilateral Pars Plana Vitrectomy, peeling of internal limiting membrane and fluid-gas exchange tamponade. The FAZ area of the SCP and DCP was statistically significantly different preoperatively and postoperatively at the 1st month in the FTMH group (0.5311 ± 0.276 mm2 vs. 0.4278 ± 0.257 mm2, p-value .000; 1.4822 ± 0.727 mm2 vs. 0.5856 ± 0.498 mm2 p-value .005). The mean preoperative FAZ in both plexuses was bigger compared to the control eyes. The FAZ area of the SCP and DCP was nonsignificantly different preoperatively and postoperatively in patients with ERM, despite a decrease in the mean FAZ area at the 1st month (0.3120 ± 0.1134 mm2 vs. 0.2300 ± 0.1158 mm2, p-value .150; 0.7100 ± 0.6607 vs. 0.5190 ± 0.5591 mm2, p-value .091). The results of this prospective study suggest that OCT-A is an effective and safe method in VRI pathologies, giving a valuable information for surgical outcome. Due to its high diagnostic value, the prognosis for the recovery of visual function after surgical treatment can be assessed.

Association of microvascular biomarkers in fluorescein angiography with macrovascular-related mortality in clinical routine data.

PurposeEarly detection of microvascular changes in the retina may be important for the risk assessment of cardiovascular health. Therefore, the purpose of this study was to investigate imaging biomarkers in fluorescein angiography (FA) as potential predictors for cardiovascular mortality.MethodsIn this retrospective, matched case-control study, we included FA images from clinical routine data between 2007 and 2018 of 100 patients who died of macrovascular events (Group 1) and 100 age- and sex-matched controls (Group 2). All patients were under treatment for different, mostly retinal, ocular diseases. FA images were used for the measurement of the foveal avascular zone (FAZ) and the arteriolar and venular caliber.ResultsPatients mean age on examination day was 69.5 ± 8.3 years with a 1:1 female:male subject ratio. Mean FAZ area of our sample was 0.340 ± 0.135 mm2 for Group 1 and 0.264 ± 0.137 mm2 for Group 2 (P < 0.001), showing a larger FAZ area in patients who subsequently died of macrovascular-related systemic diseases.ConclusionsIndividuals effected by a macrovascular-related disease show a larger FAZ on FA examinations before the event compared to patients which are unaffected. Our results highlight a possible role of the FAZ as additional biomarker for the cardiovascular condition.

The role of ocular coherence tomography angiography in the diagnosis of diabetic retinopathy and a comparison with the current gold standard fundus fluorescein angiography

Background: Diabetic retinopathy is a leading cause of preventable blindness in the world. Efficient and effective diagnosis and surveillance of diabetic retinopathy is of crucial importance to preserve the vision of patients. The FAZ (Foveal Avascular Zone) area is enlarged in patients of diabetic retinopathy. The purpose of this study was to evaluate the accuracy of OCT-A (Optical Coherence Tomography-Angiography) in delineating the FAZ area in cases of diabetic retinopathy and make a comparison with the findings of FFA (fundus fluorescein angiography) - the current gold standard.Subjects and methods: This was a comparative analytical study carried out at a tertiary care hospital in Lahore, Pakistan. A series of 50 patients, 30 males and 20 females with a mean age of 40 years were selected from the hospital outpatient department with history of five years of diabetic retinopathy. They were classified according to the ETDRS classification system into NPDR and PDR groups. The patients were booked for OCT-A, the scans were then observed for findings with a specific focus on the area of the FAZ at the level of the superficial capillary plexus. The patients then underwent same day FFA the current gold standard modality for diabetic retinopathy, thereafter a comparison between the mean area of the FAZ in both the modalities was made &amp; documented. Data was analyzed using SPSS version 25.0. Results: The FAZ was easily distinguished by both FFA and OCT-A. The mean FAZ area was 0.62 mm2 on FFA and 0.69 mm2 on OCT-A. There was a statistically significant difference between the two means (p=0.002). Both the modalities had a Sensitivity of 100% at 0.44 and 0.48 cut-offs. OCT-A had a specificity of 91.9% and FFA had a Specificity of 89.2%.Conclusions: OCT-A proved to be an effective and accurate modality in delineating the FAZ area and detecting macular ischemia in patients of diabetic retinopathy in comparison to the current Gold-Standard FFA.

Retinal Microcirculation Changes in Crohn's Disease Patients under Biologics, a Potential Biomarker of Severity: A Pilot Study.

Crohn’s disease (CD) is associated with increased cardiovascular risk and the retinal microcirculation is a reflection of the systemic microcirculation. Is the retinal microcirculation altered in relation to the severity of Crohn’s disease? This cross-sectional case-controlled study was conducted in a university hospital center from November 2020 to February 2021. We prospectively included patients with moderate (biologic therapy) or severe (biologic therapy + peri-anal disease and/or digestive resection) CD and age- and sex-matched controls. Individuals with diabetes, renal disease, cardiovascular disease, ophthalmological history or poor quality images were excluded. All participants underwent OCT angiography (OCT-A) imaging (Optovue, Fremont, CA). Analysis of covariance was used. 74 CD patients (33 moderate, 41 severe) and 74 controls (66 (44.6%) men; mean (SD) age 44 (14) years) were included. Compared with the controls, the severe CD patients showed a significantly reduced mean foveal avascular zone area (p = 0.001), superficial macular capillary plexus vessel density (p = 0.009) and parafoveal thickness (p < 0.001), with no difference in mean superficial capillary flow index (p = 0.06) or deep macular capillary plexus vessel density (p = 0.67). The mean foveal avascular zone was significantly lower in the severe than the moderate CD patients (p = 0.010). OCT-A can detect alterations in retinal microcirculation in patients with severe versus moderate CD and versus age- and sex-matched controls.

Correlation between foveal microvasculature and inner retinal layer thickness in type 2 diabetes: an optical coherence tomography angiography study

Aim The aim of this study was to evaluate the correlation between foveal microvasculature and inner retinal layer (IRL) thinning in patients with type 2 diabetes using optical coherence tomography angiography (OCTA).Patients and methods This is a prospective comparative study that included 100 eyes of 100 subjects: 50 eyes of diabetic patients with type 2 diabetes having mild to moderate nonproliferative diabetic retinopathy (NPDR) and 50 eyes of normal subjects. Foveal avascular zone (FAZ) area and vessel density of parafoveal and perifoveal areas were calculated using OCTA. The IRL thickness was measured using optical coherence tomography (OCT). The correlation between the IRL thickness and both FAZ area and macular vessel density was measured.Results The mean FAZ area was significantly larger in the NPDR group (0.69±0.01 mm2) than in the normal eyes group (0.45±0.02 mm2), (P=0.01). The mean parafoveal and perifoveal vessel density in the superficial capillary layer were significantly decreased in eyes with NPDR (46.7±6.5% and 43.8±7.1%, respectively) than in normal eyes (69.5±4.2% and 66.2±4.3%, respectively) (P=0.001). The mean parafoveal and perifoveal vessel density in the deep capillary layer had significantly lower values in eyes with NPDR (51.3±2.3% and 49.5±4.2%, respectively) than in normal eyes (70.1±5.4% and 68.3±3.73%, respectively), (P=0.001). The mean IRL thickness was significantly less in the NPDR eyes (54.7±6.8 μm) than in normal eyes (79.3±6.9 μm), (P=0.001). A statistically significant correlation was found between the IRL thickness and both FAZ area and macular vessel density in eyes with NPDR (P<0.001).Conclusion OCTA revealed that foveal microcirculatory alterations (FAZ area and macular vessel density) in diabetic eyes were related to the IRL thickness.