Characteristic changes of macular microvascular structure in central retinal vein occlusion

Objective

To explore the microvasculature changes in macular area of central retinal vein occlusion (CRVO) patients with macular edema (ME).

Methods

A cross-sectional study was conducted.Fifteen patients with monocular ME secondary to CRVO (30 eyes) and 15 age- and gender-matched normal subjects (15 eyes) were enrolled in The Second Affiliated Hospital of Chongqing Medical University from November 2017 to March 2019.Best corrected visual acuity (BCVA), intraocular pressure, slit lamp microscope with pre-set lens, color fundus photography and optical coherence tomography (OCT) were performed in all subjects.The central macular thickness (CMT), foveal avascular zone (FAZ) area, FAZ perimeter, acircularity index (AI), vessel density of superficial retinal capillary plexus (SCP) and deep retinal capillary plexus (DCP) in 3 mm×3 mm macular area were measured by optical coherence tomography angiography instrument and compared between different groups.The correlation between BCVA, CMT and microvascular structural parrameters in ME eyes of CRVO patients was analyzed by Pearson linear correlation test.This study protocol adhered to the Declaration of Helsinki and was approved by the Ethics Committee of The Second Affiliated Hospital of Chongqing Medical University (No.2018-211).Written informed consent was obtained from each subject before any medical examination.

Results

Compared with contralateral eyes, the FAZ area and FAZ perimeter of ME eyes were significantly increased, and AI, the vessel density of SCP and DCP were significantly decreased (all at P<0.01).Compared with normal control eyes, the FAZ area and FAZ perimeter of contralateral eyes of CRVO patients were significantly increased, and AI, the vessel density of DCP were significantly decreased (all at P<0.05).In ME eyes, the BCVA LogMAR was positively correlated with FAZ area and FAZ perimeter (r=0.614, 0.609; both at P<0.05), and was negatively correlated with AI and vessel density of SCP (r=-0.517, -0.593; both at P<0.058).In ME eyes, CMT was positively correlated with FAZ area and FAZ perimeter (r=0.523, 0.610; both at P<0.05), and was negatively correlated with AI and the vessel density of SCP (r=-0.537, -0.608; both at P<0.05).

Conclusions

The characteristic microvascular change in ME secondary to CRVO eyes is the decrease of blood flow caused by the decrease of capillaries in fovea, and the same change in blood flow also exists in their contralateral eyes.The degree of ME and visual function damage are correlated with the degree of foveal damage and the blood flow in fovea.

Central retinal vein occlusion; Macular edema; Tomography, optical coherence, angiography; Fluorescein fundus angiography