Surgical Outcomes of Binocular Metamorphopsia in Unilateral Epiretinal Membrane: Risk of New-Onset Binocular...

We investigated the characteristics of metamorphopsia under binocular vision (binocular metamorphopsia [BM]) in patients with unilateral epiretinal membrane (ERM) and the outcomes of vitrectomy.

Forty-five patients with unilateral ERM who underwent vitrectomy were studied. Metamorphopsia scores were measured using M-CHARTS in each eye unilaterally and under binocular vision. Patients were classified into two groups based on the presence or absence of BM. Visual functions were evaluated before and 6 months after vitrectomy.

BM was detected before surgery in 13 patients (29%; BM (+) group) and not detected in 32 patients (71%; BM (-) group). Median metamorphopsia score of the ERM-affected eye was significantly higher in the BM (+) group than in the BM (-) group (1.45 vs. 0.70, P < 0.0001). In the preoperative BM (+) group, the BM score decreased significantly from 0.25 before to 0 post-vitrectomy (P < 0.05), and BM was no longer detectable postoperatively in 7 patients (54%). Conversely, among 32 patients in the preoperative BM (-) group, new-onset BM was detected in 7 patients (22%) postoperatively, and the preoperative dominant eye was the ERM-unaffected eye in all 7 patients (P < 0.01).

In patients with unilateral ERM with severe subjective metamorphopsia, BM may be detected. Vitrectomy reduces the BM score. There is a risk of new-onset BM after surgery in some patients whose preoperative dominant eye was the ERM-unaffected eye.

The new concept of BM experienced by patients with unilateral ERM and the associated problems following vitrectomy are presented. Inclusion of binocular testing for metamorphopsia in preoperative assessments for patients with ERM is recommended.