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Prognostic value of pattern reversal visual-evoked potentials in idiopathic epiretinal membrane
M A Tilanus1, M H Cuypers, N A Bemelmans
1Institute of Ophthalmology, University Hospital Nijmegen, The Netherlands.
Background:
Prognostically favorable factors for epiretinal membrane removal have been described in the literature by several authors. Little information, however, is available about the objective assessment of the preoperative macular function. This study reports the results of idiopathic epiretinal membrane removal and the prognostic value of preoperative, pattern reversal visual-evoked potentials (PRVEPS) in recovery of visual acuity (VA).
Methods:
In 60 patients (60 eyes) with idiopathic epiretinal membrane we performed PRVEP examination preoperatively. All eyes were operated on by standard three-port vitrectomy with membrane removal. Two eyes were excluded because of postoperative complications. Follow-up VA was compared with preoperative VA for the 58 study eyes and correlated with preoperative PRVEP parameters.
Results:
The mean preoperative VA was 0.2, the mean postoperative VA, 0.4. The PRVEP was recordable in 74%, 67% and 36% of cases for check sizes of 17, 10 and 7 arcmin respectively. Twenty patients (50%) had an increase in VA of two lines or more, in 25 patients (43%) VA remained within one line of the preoperative value, and in 4 patients (7%) VA decreased by two lines or more. The mean preoperative VA was not significantly different between the group with an improved VA and the group that did not benefit from membrane removal. Of the PRVEP parameters, only the N80 latency for the 17' check size was significantly associated with postoperative visual outcome.
Conclusion:
The PRVEP is applicable as a predictor for visual outcome in cases of epiretinal membrane removal. For the 17' pattern size we found a significant association of the combination of recordability and delayed N80 latency with visual outcome.