Choroidal morphologic and vascular features in patients with unilateral idiopathic epiretinal membranes: An optical coherence tomography analysis integrated with assessment of retinal layers

Abstract

Introduction: Integrated analysis of retinal and choroidal morphologic and vascular features is urgently needed to examine whether and how these two elements interact with each other, thus contributing to visual impairment in patients with idiopathic epiretinal membranes (iERMs).

Methods: An observational retrospective study consisting of 181 patients diagnosed with unilateral iERM between August 2019 and July 2022 was carried out at Peking University Third Hospital. All patients underwent a standardized set of ophthalmologic examinations, including EDI-OCT and OCTA scanning, and were subsequently categorized into four stages according to current classification schemes based on their OCT findings. Altogether, 15 qualitative and quantitative parameters of both the retina (full-layer, inner and outer layers) and choroid were identified.

Results: The results revealed variations in the choroidal vascularity index (CVI) among different stages of iERMs (p < 0.001) for the first time. Distributions of retinal parameters across four stages of iERMs were validated. Correlation analysis between choroidal and retinal parameters showed that the CVI was associated with both inner and outer retinal morphologic biomarkers. Functional damage to retinal integrity was determined to be a strong contributor to visual acuity reduction in iERMs.

Discussion: This study complemented our present understanding of posterior segment structural and vascular alterations in iERMs.

Keywords: choroidal capillary perfusion; choroidal vascularity index; choroidal vasculature; enhanced depth imaging optical coherence tomography (EDI-OCT); idiopathic epiretinal membrane.

FIGURE 1

Flow diagram demonstrating the selection process of enrolled unilateral idiopathic epiretinal membrane (iERM) subjects.

FIGURE 2

Comparisons of choroidal parameters including CVI (A), CCP (B), and SFCT (C) between eyes with different retinal features under idiopathic epiretinal membrane conditions. CVI, choroidal vascularity index; CCP, choroidal capillary perfusion; SFCT, subfoveal choroidal thickness; CME, cystoid macular edema; EZ, ellipsoid zone; CB, central bouquet abnormality. ^aMann-Whitney test. ^bKruskal-Wallis test.

FIGURE 3

Multiple regression and correlation analysis to determine the OCT morphologic factors related to best-corrected visual acuity in idiopathic epiretinal membranes. CRT, central retinal thickness; CME, cystoid macular edema; GCL + IPL, ganglion cell layer + inner plexiform layer; INL, inner nuclear layer; EZ, ellipsoid zone; CB, central bouquet; PROS, photoreceptor outer segment; CVI, choroidal vascularity index; CCP, choroidal capillary perfusion; BCVA, best corrected visual acuity. ^aOCT parameters with statistically solid and integral values across four stages of idiopathic epiretinal membranes were included in multiple regression analysis, which ruled out thickness of specific retinal layer for the disrupted retinal structure in higher stages of iERMs. Subfoveal choroidal thickness and choroidal area parameters were also excluded for their comparable value among four groups and lack of correlation to BCVA. ^bSpearman correlation analysis was used for continuous variables and Kendall’s tau-b correlation analysis was used for categorical variables.