Preferential Hyperacuity Perimeter and Prognostic Factors for Metamorphopsia After Idiopathic Epiretinal Membrane Surgery

Abstract

To document changes in metamorphopsia via preferential hyperacuity perimeter and to identify prognostic factors related to favorable metamorphopsia outcome after idiopathic epiretinal membrane surgery. Prospective, consecutive, interventional case series. We prospectively included 29 eyes of 27 patients who underwent successful vitrectomy for idiopathic epiretinal membrane. All eyes underwent examinations before surgery and at 2weeks and 1, 3, and 6months after surgery. Metamorphopsia was assessed by using a preferential hyperacuity perimeter. Several clinical factors were analyzed to reveal relationships with final metamorphopsia outcome, including the duration of symptoms, best-corrected visual acuity, and spectral-domain optical coherence tomography findings. Spectral-domain optical coherence tomography findings included assessment of central foveal thickness, and the integrity of the photoreceptor inner segment and outer segment (IS/OS) junction. At baseline, preferential hyperacuity perimeter detected areas of distortion in 15 eyes (51.7%). At 6months after surgery, there was significant reduction in metamorphopsia (P= .001), which was paralleled with significant improvement of best-corrected visual acuity and reduction of central foveal thickness (P < .001). At 6months after surgery, the degree of metamorphopsia was related significantly to the severity of preoperative metamorphopsia and central foveal thickness at baseline (ρ= 0.856; P < .001; ρ= 0.412; P= .027; respectively). Eyes with broadly disrupted IS/OS junction of more than 200μm before surgery revealed significantly poorer postoperative metamorphopsia than those with intact or narrowly disrupted IS/OS junction (P= .001). However, duration of symptoms and baseline best-corrected visual acuity were not correlated with final metamorphopsia (P= .625 and P= .052, respectively). Significant reduction of metamorphopsia paralleled the improvement of best-corrected visual acuity and central foveal thickness until 6months after idiopathic epiretinal membrane surgery. The significant predictors for postoperative metamorphopsia outcome were the degree of preoperative metamorphopsia, central foveal thickness, and the photoreceptor IS/OS junction integrity at baseline.