Prediction of postoperative visual outcome after pars plana vitrectomy based on preoperative multifocal electroretinography in eyes with diabetic macular edema.

BACKGROUND

To evaluate the role of preoperative optical coherence tomography (OCT), multifocal electroretinography (mfERG), and fluorescein angiography (FA) as prognostic factors for vision after pars plana vitrectomy (PPV) in diabetic macular edema (DME).

METHODS

Thirty-five eyes of 34 patients who underwent PPV were retrospectively reviewed. Best-corrected visual acuity (VA) was measured at baseline, and at 3, 6, and 9 months after surgery. Patients were categorized into two groups according to the final VA. Group 1 consisted of eyes with 0.2 or more logMAR lines of visual recovery, the rest of the eyes being placed in group 2. Preoperative FA findings, central macular thickness and mfERG responses at the central macula were evaluated to determine their effect on visual outcome.

RESULTS

Eighteen eyes showed improved VA after PPV, and were classified into group 1. Seventeen eyes were placed in group 2. The presence of macular ischemia did not affect the postoperative visual outcome between the groups, although a trend was noted toward macular ischemia with delayed implicit time. P1 implicit time at the central seven hexagons (eccentricity of 0-5 degrees ) was the only statistically significant factor predicting unfavorable visual outcome. There was significantly delayed implicit time in group 2 patients compared with those of group 1. MfERG responses at other retinal eccentricities and central macular thickness did not show significant association with visual prognosis.

CONCLUSIONS

Preoperative mfERG parameters, especially the implicit time, can be useful indicators for predicting functional visual prognosis after PPV in DME.