Focal macular electroretinograms before and after successful macular hole surgery

PURPOSE: To report changes in focal macular electroretinograms before and after successful macular hole surgery and to discuss whether preoperative retinal function can predict postoperative visual acuity. METHODS: In this prospective study, 28 consecutive eyes of 28 patients underwent vitrectomy for stage 2 or 3 full-thickness idiopathic macular hole. Focal macular electroretinograms using a 4-degree stimulus spot were obtained in 24 eyes of 28 patients, and those using a 5-degree stimulus spot were obtained in 24 eyes of 28 patients, to evaluate preoperative and postoperative amplitude and implicit time of the b-wave. Visual acuity was measured preoperatively and postoperatively, and results were translated into logMAR (minimum angle of resolution) values. RESULTS: After successful macular hole closure, the b- wave amplitude increased in 23 of 24 eyes measured with the 4-degree stimulus spot and in 19 of 24 eyes measured with the 5-degree stimulus spot. Postoperative b-wave amplitude recorded with either stimulus spot correlated with postoperative corrected visual acuity. The b-wave implicit time decreased in 15 of 20 eyes measured with the 4-degree spot and in 13 of 23 eyes measured with the 5-degree spot. Preoperative b-wave implicit time measured with the 5-degree stimulus spot correlated significantly (P = .001) with postoperative corrected visual acuity. CONCLUSIONS: Qualitative change (implicit time) is more important than quantitative change (amplitude) in electroretinograms for predicting postoperative corrected visual acuity. The function of the retinal tissue surrounding the hole may affect visual outcome.