Evaluation of the correlation between quantitative measurement of the foveal avascular zone and retinal vessel density and outer retinal disruptions in diabetic patients

Evaluation of Retinal Vessel Density and Foveal Avascular Zone in Unilateral Exudative Choroidal Neovascularization by Optical Coherence Tomography Angiography

Objectives

To evaluate treatment-naïve patients with neovascular-exudative age-related macular degeneration (eARMD) in one eye and early-/intermediate-stage nonexudative ARMD (neARMD) in the fellow eye by optical coherence tomography-angiography (OCTA).

Methods

A total of 70 eyes of 35 patients (17 females) with first diagnosis of eARMD in one eye and early/intermediate-stage neARMD in the fellow eye were included in this study. The eARMD diagnosis was confirmed by fluorescein angiography. Each subject underwent OCTA imaging by RTVue XR Avanti OCT device. Capillary vessel density (VD) of superficial (SCP) and deep (DCP) retinal capillary plexuses and foveal avascular zone (FAZ) parameters were measured.

Results

The mean age was 72.0±8.9 years (range 59-87). The mean visual acuity was 0.7±0.5 logMar for the eARMD eyes and 0.4±0.3 logMar for the fellow eyes (p=0.012). Nineteen patients (54.3%) had occult choroidal neovascularization (CNV), and 16 patients (45.7%) had classical CNV. The mean FAZ area was measured 0.30 ± 0.11 mm2 in the eARMD eyes and 0.27±0.11 mm2 in the fellow eyes (p=0.387). The FAZ circularity index measurement was 1.15±0.03 in eARMD eyes and 1.11±0.05 in the fellow eyes (p=0.014). There was no statistically significant difference in any measure of the macular SCP and DCP's VD between eARMD eyes and their fellow eyes.

Conclusion

Potential retinal vascular alterations will be important in ARMD pathogenesis.

Compensatory contribution of retinal larger vessels to perfusion density in diabetics without retinopathy

Vessel and perfusion densities may decrease before diabetic retinopathy appears; it is unknown whether these changes affect the contribution of vessel density to perfusion density. This was a non-experimental, comparative, prospective, cross-sectional study in non-diabetic subjects (group 1) and diabetics without retinopathy (group 2). Vessel and perfusion densities in the superficial capillary plexus were compared between groups at the center, inner, and full regions and by field (superior, temporal, inferior, nasal) using optical coherence tomography angiography. Coefficients of determination (R²) between vessel and perfusion densities were calculated to find the contribution of larger retinal vessels to perfusion density. Percent differences were used to evaluate the contribution of these vessels to perfusion density in a regression model. There were 62 participants, 31 eyes by group; vessel and perfusion densities as well as the coefficients of determination between them were lower in group 2, especially in the nasal field (R² 0.85 vs. 0.71), which showed a higher contribution of larger retinal vessels to perfusion density. The regression model adjusted to a quadratic equation. In diabetics without retinopathy the contribution of vessel density to perfusion density may decrease; a low vessel density may increase the contribution of larger retinal vessels to perfusion density.

Factors based on optical coherence tomography correlated with vision impairment in diabetic patients

The aim of this study is to evaluate the relationship between retinal structures and visual acuity in diabetic patients using optical coherence tomography (OCT) and OCT angiography (OCTA). This study was a retrospective observational study conducted at a single medical center in Japan. Evaluation of retinal images was analyzed using spectral domain OCT. Twelve factors including central retinal thickness, length of disorganization of retinal inner layer (DRIL), number of inner hyperreflective foci, number of outer hyperreflective foci, height of intraretinal fluid, height of subretinal fluid, length of external limiting membrane disruption, length of external ellipsoid zone (EZ) disruption, vessel density of superficial capillary plexus (SCP), foveal avascular zone (FAZ) area, and FAZ circularity were analyzed based on OCT/OCTA findings. Multivariate analysis was used to investigate the OCT-based factors that could be correlated with poor visual acuity in treatment-naïve diabetic eyes. A total of 183 eyes of 123 diabetic patients with type 2 diabetes (mean age 61.9 ± 12.3 years, 66 men and 57 women) and 62 eyes of 55 control subjects (mean age 64.4 ± 12.5 years, 15 men and 40 women) was enrolled in this study. Multiple regression analysis showed that OCT-based factors correlated with visual acuity were length of DRIL (β = 0.24, P < 0.01), length of EZ disruption (β = 0.35, P < 0.001), and FAZ circularity (β =  - 0.14, P < 0.05). The other factors showed no significant correlation. In conclusion, the length of DRIL, length of EZ disruption, and FAZ circularity measured by OCT were identified as related factors for visual impairment in treatment-naïve diabetic eyes.

Dilated retinal large vessels and capillaries associated with diabetic macular edema and photoreceptor loss respectively

PURPOSE

Previously, we measured retinal large vessels and capillaries separately on optical coherence tomography angiography (OCTA). In the present study, we aim to evaluate the role of these parameters in association to diabetic macular edema (DME) and ellipsoid zone disruption (EZD).

METHODS

In this cross-sectional study, 54 eyes from 31 patients (10 females, 31 Asians) with severe non-proliferative diabetic retinopathy (25 eyes) or proliferative diabetic retinopathy (PDR, 29 eyes) were enrolled. All eyes underwent 3 × 3 mm OCTA scans centered on the fovea. Perfusion density (PD), vessel length density (VLD), and vessel diameter index (VDI) were calculated for retinal large vessels and superficial capillaries separately. Other OCTA findings included suspended scattering particles in motion (SSPiM), number of microaneurysms (MA) in all retinal layers, and the area of foveal avascular zone (FAZ) of superficial capillary plexus. DME and EZD were evaluated on B-scans. Both univariate and multivariate analysis were performed.

RESULTS

Of the 54 study eyes, 31 (57%) had DME and 21 (40%) had EZD. Multivariate regression model showed that PDR (β = 27.8, 95% confidence interval (CI): 2.7-282.8, p = 0.005), more MA (β = 2.5, 95% CI: 1.3-4.5, p = 0.003), and increased VDI of larger vessels (β = 1.9, 95% CI: 1.0-3.5, p = 0.047) were risk factors for DME. As for EZD, presence of SSPiM (β = 5.5, 95% CI: 1.2-26.1, p = 0.032) and increased VDI of capillaries (β = 3.9, 95% CI: 1.1-13.8, p = 0.034) were risk factors.

CONCLUSIONS

In eyes with diabetic retinopathy, dilation of retinal larger vessels was associated with macular edema, while dilation of retinal capillaries was associated with ellipsoid zone disruption.