Fourier-domain optical coherence tomography of eyes with idiopathic epiretinal membrane: correlation between macular morphology and visual function

Purpose

The purpose of this study is to evaluate the macular morphological changes associated with idiopathic epiretinal membrane (iERM) using high-resolution Fourier-domain optical coherence tomography (FD-OCT), as they correlate with visual acuity and microperimetry (MP-1).

Methods

In all, 24 eyes (19 subjects) with iERM were imaged prospectively using FD-OCT with axial resolution of 4.5?μm and transverse resolution of 10 to 15?μm. MP-1 and Stratus OCT were carried out in a subset of eyes.

Results

The mean log of the minimum angle of resolution best-corrected visual acuity (BCVA) was 0.18±0.16 (range: ?0.08 to 0.48, Snellen equivalent 20/15^?1 to 20/60). ERM was visualized in all 24 eyes with FD-OCT and in 17 eyes (85%) of 20 eyes imaged with Stratus OCT. Although BCVA correlated with macular thickening in the central 1?mm sub-field of the Stratus ETDRS (P=0.0005) and macular volume (central 3?mm area) on FD-OCT (P<0.0001), macular thickening on thickness map and volume correlated poorly with decrease in macular sensitivity on MP-1 (P=0.16). On FD-OCT, foveal morphological changes correlated best with decrease in BCVA, the strongest being central foveal thickness (P<0.0001). Other significant changes included blurring of the foveal inner segment–outer segment (IS–OS) junction and/or Verhoeff''s membrane, vitreal displacement of foveal outer nuclear layer and foveal detachment (P<0.05). Foveal IS–OS junction disruption was seen in 25% of eyes on Stratus OCT but in none of the eyes on FD-OCT.

Conclusion

FD-OCT allowed improved visualization of ERM and associated foveal morphological changes that correlated best with BCVA. Macular thickening correlated weakly with decreased macular function as assessed by MP-1.