Abstract
Abstract: :
Purpose: Diabetic macular edema (DME) can be treated by vitrectomy, but visual outcomes varies from patient to patient. To predict the postoperative visual acuity, multifocal ERG (mfERG) was applied preoperatively. Methods: MfERG was recorded (VERIS, EDI Inc., CA) preoperatively in 22 eyes of 22 diabetic patients (mean 62.2 ± S.D. 7.3 years old) with diffuse macular edema. The eyes with hard exudate, retinal atrophy or cyst in the fovea were excluded. Focal ERG (first order kernel) from the central area (central ERG), and sum of all focal ERGs (total ERG) were analyzed. Preoperative visual acuity (PreVA) and the best postoperative acuity (PostVA) were measured. All eyes were followed for more than 1 year. Visual acuity was converted to log MAR for statistical analysis. Results: There was no correlation between the amplitude of central or total ERG and PreVA or PostVA. There was no correlation between the peak time of central or total ERG and PreVA or Post VA. However, the ratio of the amplitude of central ERG to that of total ERG(C/T ratio) was positively correlated to PostVA (P=0.05, r2=0.25), although there was no correlation between C/T ratio and PreVA using a linear regression and correlation analysis. Conclusions: Abnormal mfERG in DME has been reported previously, but it did not predict postoperative visual outcomes. On the other hand, our results suggest that the C/T ratio can be an indicator of PostVA. The C/T ratio probably indicates relative dysfunction of the fovea, and this kind of geometric analysis for retinal dysfunction using mfERG may be a useful tool for management of DME.
Keywords: diabetic retinopathy • electroretinography: clinical • vitreoretinal surgery