Quantitative analysis of optical coherence tomography angiography metrics in diabetic retinopathy.

PURPOSE: To evaluate the correlation of the visual acuity and diabetic retinopathy stage using optical coherence tomography and optical coherence tomography angiography metrics. METHODS: In this prospective study, optical coherence tomography and optical coherence tomography angiography images of patients with different stages of diabetic retinopathy were obtained. In optical coherence tomography angiography images, the size of foveal avascular zone, central macular thickness, and vessel density at superficial and deep capillary layers of the macula were measured. In optical coherence tomography images, the presence of intraretinal cyst, disorganization of retinal inner layer, and ellipsoid zone and external limiting membrane disruption were evaluated. The associations between the variables with visual acuity and diabetic retinopathy stage were analyzed. RESULTS: In total, 68 eyes of 38 patients with a mean age of 58.96 ± 10.59 years were included. In total, 34 eyes were categorized as non-proliferative diabetic retinopathy, 14 as active, and 20 as regressed proliferative diabetic retinopathy. Univariate analysis showed deep parafoveal vessel density, central macular thickness, ellipsoid zone disruption, disorganization of retinal inner layer, and external limiting membrane disruption had a significant relationship with visual acuity. However, in multivariate analysis, only central macular thickness and ellipsoid zone disruption had significant association with visual acuity (p = 0.02 and p = 0.01, respectively). There was a significant difference in deep parafoveal vessel density (p = 0.04), but not in foveal avascular zone area, between different stages of diabetic retinopathy. CONCLUSION: In this study, the foveal avascular zone area did not correlate with visual acuity and different stages of diabetic retinopathy. Structural abnormalities on optical coherence tomography images with especial focus on outer retinal disruption provided more reliable predictors for visual acuity outcomes in patients with diabetic retinopathy.

Correlation of optic disc morphometry and optic disc microvasculature assessed with optical coherence tomography angiography.

OBJECTIVE: To compare optic disc microvasculature measurements to the disc morphometrics in normal eyes. DESIGN: Cross-sectional study. PARTICIPANTS: Fifty-eight healthy subjects. METHODS: Enface 4.5x4.5 mm optical coherence tomography angiography images were obtained from the optic disc of healthy individuals. The radial peripapillary capillary (RPC) and the nerve head (NH) en face images were obtained. Also, spectral domain OCT measurements of the peripapillary nerve fibre layer (NFL) thickness were recorded. Correlations of the vessel density and NFL measurements with optic disc morphometrics were analyzed. RESULTS: Fifty-eight eyes of 58 patients were included. Mean peripapillary NFL thickness was 99.77 ± 8.47 µm. The mean disc area was 2.15 ± 0.34 mm2 (range, 1.48-3.02 mm2) with an average cup/disc area ratio of 0.27 ± 0.14 (range, 0.0-0.6). On the RPC en face image, the mean vessel density of the whole image, peripapillary, and inside disc was 55.52 ± 2.90, 62.42 ± 3.30, and 45.77 ± 9.24%, respectively. On the NH en face images, the mean vessel density of the whole image, peripapillary, and inside disc was 55.69 ± 3.04, 60.15 ± 2.79, and 52.69 ± 5.31%, respectively. The NH vessel density in the inside disc area correlated with the cup/disc area ratio (R = -0.44, p < 0.001). The association of RPC vessel density in the inside disc area with the cup/disc area ratio was significant (R= -0.88, p < 0.001). The RPC vessel density in the peripapillary area correlated with the cup/disc area ratio (R = 0.37, p = 0.004). Also, the RPC vessel density in the whole image was associated with the peripapillary NFL thickness (R = 0.32, p = 0.01). CONCLUSION: We observed a significant negative correlation between inside disc vessel density and cup/disc area ratio, but not to the disc area in normal eyes. In addition, the whole image RPC vessel density was revealed to be weakly correlated with the average RNFL thickness.

Foveal Avascular Zone and Vessel Density in Healthy Subjects: An Optical Coherence Tomography Angiography Study.

PURPOSE: To report the normal characteristics and correlations of the foveal microvascular networks using optical coherence tomography angiography (OCTA) in a healthy Iranian population. METHODS: Enface 3x3 OCTA images were obtained using the RTVue Avanti spectral-domain optical coherence tomography with AngioVue software (Optovue, Fremont, CA, USA). Foveal avascular zone (FAZ) area, central foveal point thickness and inner retinal thickness at the foveal center and the vascular density of the superficial retinal capillary plexus (SCP) and deep retinal capillary plexus (DCP) in the fovea were recorded. RESULTS: Seventy normal eyes of 70 subjects (range, 9 to 71 years) were studied. Mean FAZ area was 0.32 ± 0.11 (range, 0.13-0.67) mm2 in SCP and 0.50 ± 0.13 (range, 0.19-0.94) mm2 in DCP. Mean SCP vessel density was 29.6 ± 4.7 (range, 16.3-40.3) % in the fovea. Mean DCP vessel density was 27.0 ± 5.9 (range, 15.0-45.2) % in the fovea. The FAZ area at SCP level was negatively correlated to the central subfield thickness (P < 0.001). The FAZ area at DCP level correlated negatively to the central subfield thickness and was significantly associated to age (both P < 0.001). The foveal SCP vessel density significantly correlated with foveal thickness and the foveal DCP vessel density correlated significantly with central foveal subfield thickness and was inversely related to age (all P < 0.05). CONCLUSION: In this study, central foveal subfield thickness was a major determinant of the FAZ size and foveal vessel density. Age was a determinant for FAZ area and whole image vessel density in DCP.