Internal Limiting Membrane Folding in Epiretinal Membrane: Prevalence, Morphologic Characteristics, and Clinical Implications

Abstract

Purpose : Previous studies on epiretinal membrane (ERM) have focused on ERM itself; however, associated retinal change in eyes with ERM has not been extensively studied. We aimed to assess prevalence and morphologic characteristics of internal limiting membrane and superficial retinal fold (ILM fold) in eyes with epiretinal membrane (ERM) and to evaluate the association between the change in ILM fold and ERM progression.

Methods : ILM fold was defined as the hyporeflective lines on confocal scanning laser ophthalmoscopy (cSLO; Nidek, Japan) red-free image which correspond to the folds in the ILM or superficial retinal layers on optical coherence tomography (OCT). Ninety eyes of 81 patients with ERM, shown as hyperreflective membrane on SD-OCT and cSLO, were imaged by color fundus photography, cSLO, and spectral-domain OCT (3D-OCT, Topcon, Japan) to evaluate the presence and progression of the ERM and ILM fold. In the patients with follow-up periods > 2 years before the ERM surgery, the progression or regression of ERM was matched to that of the ILM fold.

Results : Among the 90 eyes, 84 (93.3%) eyes showed the ILM fold radiating from margin of ERM. Detection rate of the ILM fold was 40.0%, 93.3%, and 91.1% for color fundus photograph, cSLO, and 3D-rendeing image of SD-OCT, respectively. Immediately after ERM peeling combined with ILM peeling, the ILM fold disappeared in all the patients. ERM progression, either (1) macular thickening or foveal contour change with ERM thickening or (2) the area of involvement increased by more than 10%, showed excellent agreement with ILM fold progression (kappa value [κ]= 1.0). Functionally, ILM fold change showed good agreement with visual acuity change (κ = 0.63).

Conclusions : ILM fold, shown as radiating hyporeflective lines from the margin of ERM on cSLO and SD-OCT, can be noted in eyes with ERM. cSLO and SD-OCT may be excellent modalities to detect and monitor ILM fold. The ILM fold may be clinically useful as an indicator of anatomic and functional ERM progression.