Optical Coherence Tomography of Idiopathic Macular Epiretinal Membranes Before and After Surgery

Purpose: To examine the preoperative and postoperative anatomical features of the macula using optical coherence tomography in patients who underwent surgery for epiretinal membrane and to correlate these features with functional results.

Methods: In a noncomparative interventional series, 62 eyes of 62 consecutive patients operated on for an idiopathic epiretinal membrane were followed up using a standardized protocol. Preoperative and postoperative examination included best-corrected visual acuity using an Early Treatment Diabetic Retinopathy Study chart, biomicroscopy of the fundus with a contact lens, fundus photography with blue and green filters, fluorescein angiography, and optical coherence tomography.

Results: Median preoperative visual acuity was 20/60 (range, 20/32 to 20/320). Median postoperative visual acuity was 20/40 (range, 20/20 to 20/160). Fifty-one eyes (82%) obtained visual acuity of 20/50 or better. Preoperatively, all eyes had increased macular thickness (mean, 419 +/- 105 microm; range, 265.5 to 689 microm), with disappearance of the foveal pit. An epiretinal membrane was visible on optical coherence tomography scans in 26 cases (42%). Intraretinal cystic spaces were present in the thickened macular tissue in 15 cases but corresponded to cystoid macular edema on fluorescein angiography in only three. Postoperatively, mean macular thickness decreased to 300 +/- 65 microm (range, 185 to 511 microm) but returned to normal in only three eyes. The foveal pit reappeared in 20 eyes. Preoperatively, visual acuity correlated with macular thickness (r = 0.56, P <.0001), but not postoperatively (r = 0.12, P =.37).

Conclusion: Macular thickness decreases after epiretinal membrane surgery, but the macular profile rarely returns to normal. However, this does not preclude satisfactory improvement of visual acuity.