Correlation Between Thickening of the Inner and Outer Retina and Visual Acuity in Patients With Epiretinal Membrane

In Brief Purpose: The purpose of this study was to examine the relationship between thickening of the inner and outer retinal layers and visual acuity in patients with idiopathic epiretinal membrane. Methods: We examined 30 eyes of 30 patients and 25 eyes of 25 healthy volunteers as age-matched normal control subjects. The inner (between the vitreoretinal interface and the outer border of inner plexiform layer), outer, and full retinal thickness at the fovea, parafovea, and perifovea were measured using spectral-domain optical coherence tomography. Results: Thickening ratios of both the inner and outer retina were greater in the fovea than in the other macular regions (P < 0.0001). Inner foveal retinal thickening was significantly greater than outer foveal retinal thickening (P < 0.0001). However, outer retinal thickening in the fovea (r = 0.644, P < 0.001), parafovea (r = 0.616, P < 0.001), and perifovea (r = 0.410, P = 0.025) was significantly correlated with visual acuity; inner retinal thickening was not. Visual acuity tended to be worse, although not significantly so, in eyes with photoreceptor disruption. Conclusion: Epiretinal membrane-induced retinal damage associated with visual acuity seems to be located within the outer retina external to the inner plexiform layer. Although inner retinal thickening internal to the outer border of the inner plexiform layer was significantly greater than outer retinal thickening external to the inner plexiform layer, visual acuity was correlated with outer, but not inner, retinal thickening, suggesting that damage to the outer retina is associated with the visual impairment.