Preferential hyperacuity perimeter and prognostic factors for metamorphopsia after idiopathic epiretinal membrane surgery

Abstract

Purpose: To document changes in metamorphopsia via preferential hyperacuity perimeter and to identify prognostic factors related to favorable metamorphopsia outcome after idiopathic epiretinal membrane surgery.

Design: Prospective, consecutive, interventional case series.

Methods: We prospectively included 29 eyes of 27 patients who underwent successful vitrectomy for idiopathic epiretinal membrane. All eyes underwent examinations before surgery and at 2 weeks and 1, 3, and 6 months 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.

Results: At baseline, preferential hyperacuity perimeter detected areas of distortion in 15 eyes (51.7%). At 6 months 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 6 months 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 200 μm 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).

Conclusions: Significant reduction of metamorphopsia paralleled the improvement of best-corrected visual acuity and central foveal thickness until 6 months 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.