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

Abstract

[한글]

[영문]

This study is to evaluate the role of preoperative optical coherence tomography (OCT) and multifocal electroretinography (mfERG) as prognostic factors for visual outcome after pars plana vitrectomy (PPV) treatment of diabetic macular edema (DME). Thirty-five eyes of 34 patients with DME who underwent PPV with minimum follow-up time of 9 months 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 value. Group 1 consisted of eyes with 0.2 or more logMAR lines of visual recovery, and group 2 of eyes with less than 0.2 logMAR lines or which had worsened at last follow-up visit. Preoperative central macular thickness and mfERG responses (P1 amplitude and implicit time) at central macula, up to 15°, were evaluated and compared between the two groups. Eighteen eyes (51%) showed improved VA after PPV, and were classified into group 1. Seventeen eyes (49%) were placed in group 2. Among mfERG responses at an eccentricity of 0-15°, P1 implicit time at the central seven hexagons (eccentricity of 0-5°) was significantly delayed in group 2 patients compared with those of group 1 (P=0.017, Student’s t-test). However, no significant difference was noted at any other retinal eccentricity. Neither P1 amplitude nor central macular thickness showed any significant between-group difference. There was a modest correlation between preoperative VA value and central macular thickness. The slope of the best-fit line was approximately 0.1 logMAR of improved VA for every 100 μm decrease in macular thickness. No significant correlation was noted between preoperative central macular thickness and mfERG response, at an eccentricity of 0-5°. In conclusion, preoperative mfERG parameters, especially implicit time, can be useful to predict functional visual outcome prognosis after PPV in patients with DME.