Abstract
Purpose :
To compare and describe the morphological characteristics of idiopathic and secondary Epiretinal Membranes (ERM) using en-face images from spectral domain optical coherence tomography (SD-OCT).
Methods :
A total of 75 eyes from 56 consecutive patients evaluated from 2022 through 2023 were included. Customized en-face slabs
(covering a foveal center area of 6.4 mm x 6.4 mm with a thickness of 6 μm) were created to visualize the ERM. For each eye, six consecutive en-face slabs were constructed along the axial axis: three slabs with anterior axial localization to the inner limiting membrane (ILM) and three with posterior axial localization. The anterior and posterior boundaries were set up to 18 μm from the ILM. Out of these six slabs, the one best highlighting ERM features was selected by an expert. An en-face ERM pattern classification was developed based on the total ERM area and the number of traction foci (unifocal, multifocal, and diffuse) (Fig 1). The area and pattern of ERM were compared between primary/idiopathic and secondary ERM eyes.
Results :
Out of the 75 eyes, 42 were idiopathic ERM, with a median age of 71 years (IQR 9.0), and 33 were secondary ERM, with a median age of 69 years (IQR 16.0). Idiopathic ERM eyes had a high proportion of membranes with a unifocal pattern (83.3%), whereas secondary ERM eyes predominantly showed diffuse pattern membranes (90.0%) (Wilcoxon rank sum test, p=2.335 e−06) (Fig 2). This finding aligns with the differences in ERM area between primary/idiopathic and secondary ERMs, where idiopathic ERMs had a smaller average area (12.9 mm2, IQR 15.3) compared to secondary ERMs (21.5 mm2, IQR 18.8) (Wilcoxon rank sum test, p=0.002).
Conclusions :
The SD-OCT en-face approach may reveal additional characteristics of ERMs. Differences observed between idiopathic and secondary ERMs appear to be closely related to their distinct pathophysiological processes. Specifically, more extensive and diffuse membranes were found in eyes with secondary ERMs. This is likely due to the fact that secondary ERMs develop in a highly inflammatory local environment, in contrast to the conditions leading to idiopathic ERMs.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.