[Use of the multifocal electroretinogram to evaluate retinal function after pars plana vitrectomy for diabetic macular edema]

Abstract

Purpose: Multifocal electroretinograms (multifocal ERGs) were performed to evaluate retinal function in patients with diabetic macular edema.

Materials & methods: Eight eyes of 5 patients underwent pars plana vitrectomy for diabetic macular edema. Multifocal ERGs, fundus examinations, and fluorescent angiographies were done both before and after the operation.

Results: Post-operative visual acuity was improved by two or more lines in 3 eyes. In multifocal ERGs, the amplitude of the positive wave (P1) from the macular area decreased transiently after surgery (p < 0.05), but it improved with the passage of time. The P1 amplitude from the peripheral area was decreased throughout the observation period of six months (p < 0.05). For both areas, the P1 latency was increased significantly (p < 0.05) at one month post-operatively, and then decreased.

Conclusion: These findings are consistent with the possibility that the surgical method, especially removal of the posterior cortical vitreous, can cause retinal damage.