An Analysis of Optical Coherence Tomography Angiography (OCT-A) Perfusion Density Maps in Patients Treated for Retinal Vein Occlusion with Intravitreal Aflibercept

Correlation between macular perfusion status and visual acuity in retinal vein occlusion

OBJECTIVES

Retinal vein occlusion (RVO) is the second most common retinal vascular disease worldwide, and the retinal perfusion status is closely related to the prognosis of the disease. Macular perfusion status is particularly correlated with visual acuity. This study aims to investigate the changes in macular perfusion indicators in RVO using optical coherence tomography angiography (OCTA) and analyze the correlation between macular perfusion status and visual acuity.

METHODS

This cross-sectional study included 41 RVO patients, who were divided into 2 groups based on the occlusion site: 18 cases in the central retinal vein occlusion (CRVO) group and 23 cases in the branch retinal vein occlusion (BRVO) group. Additionally, they were categorized into ischemic RVO (23 cases) and non-ischemic RVO (16 cases) groups based on the presence of ischemia (2 eyes were excluded due to hemorrhage obscuring the peripheral retina, making it impossible to confirm the area of non-perfusion). A control group of 29 healthy individuals matched by sex and age was also recruited. Macular perfusion indicators were measured using OCTA, and the correlation between macular perfusion status and visual acuity was analyzed.

RESULTS

Compared with healthy eyes, RVO eyes showed an increased foveal avascular zone (FAZ) area and significantly reduced superficial and deep vessel density (P<0.001). However, there were no significant differences in central foveal thickness (CFT) or macular perfusion indicators between the CRVO and BRVO groups (P>0.05). The best corrected visual acuity (BCVA) at the logarithm of the minimum angle of resolution (logMAR BCVA) was significantly negatively correlated with both superficial and deep retinal vessel density in RVO eyes (unstandardized coefficient B=-0.039, B=-0.042; P=0.017, P=0.040). The average BCVA in the ischemic RVO group was significantly worse than that in the non-ischemic RVO group (0.82±0.44 vs 0.45±0.29, P=0.007). The ischemic RVO group also had a larger FAZ area (P=0.003) and lower superficial and deep retinal vessel density (P<0.001, P=0.008, respectively) compared with the non-ischemic RVO group. The severity of macular ischemia did not correspond directly with the peripheral ischemia severity in RVO.

CONCLUSIONS

Macular perfusion status is significantly reduced in RVO eyes compared to healthy eyes, which negatively impacts and limits visual acuity in RVO patients. Eyes with ischemic RVO have poorer visual acuity and macular perfusion status than those with non-ischemic RVO. OCTA is advantageous for observing vascular morphology and quantifying macular perfusion status, making it an effective tool for assessing disease progression.

Choriocapillaris and Retinal Vascular Alterations in Presymptomatic Alzheimer's Disease

Purpose

To compare optical coherence tomography angiography (OCTA) retina metrics between cognitively healthy subjects with pathological versus normal cerebrospinal fluid (CSF) Aβ42/tau ratios.

Methods

Swept-source OCTA scans were collected using the Zeiss PLEX Elite 9000 and analyzed on 23 cognitively healthy (CH) subjects who had previously undergone CSF analysis. Thirteen subjects had a pathological Aβ42/tau (PAT) ratio of <2.7132, indicative of presymptomatic Alzheimer's disease (AD), and 10 had a normal Aβ42/tau (NAT) ratio of ≥2.7132. OCTA en face images of the superficial vascular complex (SVC) and deep vascular complex were binarized and skeletonized to quantify the perfusion density (PD), vessel length density (VLD), and fractal dimension (FrD). The foveal avascular zone (FAZ) area was calculated using the SVC slab. Choriocapillaris flow deficits (CCFDs) were computed from the en face OCTA slab of the CC. The above parameters were compared between CH-PATs and CH-NATs.

Results

Compared to CH-NATs, CH-PATs showed significantly decreased PD, VLD, and FrD in the SVC, with a significantly increased FAZ area and CCFDs.

Conclusions

Swept-source OCTA analysis of the SVC and CC suggests a significant vascular loss at the CH stage of pre-AD that might be an indicator of a neurodegenerative process initiated by the impaired clearance of Aβ42 in the blood vessel wall and by phosphorylated tau accumulation in the perivascular spaces, a process that most likely mirrors that in the brain. If confirmed in larger longitudinal studies, OCTA retinal and inner choroidal metrics may be important biomarkers for assessing presymptomatic AD.