Contrast and glare sensitivity in epilepsy patients treated with vigabatrin or carbamazepine monotherapy compared with healthy volunteers

Background/aim-Many antiepileptic drugs have influence on visual functions. The aim of this study was to investigate possible changes in contrast sens itivity, macular photostress, and brightness acuity (glare) tests in patien ts with epilepsy undergoing vigabatrin (VGB) or carbamazepine (CBZ) monothe rapy compared with healthy volunteers. Methods-32 patients undergoing therapy, 18 patients undergoing CBZ therapy, and 35 healthy volunteers were asked to participate in an ophthalmological examination. In the previous study, visual field constrictions were report ed in 40% of the patients treated with VGB monotherapy. In the present stud y, these VGB and CBZ monotherapy patients were examined for photopic contra st sensitivity with the Pelli-Robson letter chart and brightness acuity and macular photostress with the Mentor BAT brightness acuity tester. Results-Contrast sensitivity with the Pelli-Robson letter chart showed no d ifference between these groups and normal subjects (ANOVA: p= 0.534 in the right eye, p= 0.692 in the left eye) but the VGB therapy patients showed a positive correlation between the contrast sensitivity values and the extent s of the visual fields in linear regression (R = 0.498, p = 0.05 in the rig ht eye, R = 0.476, p = 0.06 in the left eye). Macular photostress and glare tests were equal in both groups and did not differ from normal values. Conclusion-The results of this study indicate that carbamazepine therapy ha s no effect on contrast sensitivity. Vigabatrin seems to impair contrast se nsitivity in those patients who have concentrically constricted in their vi sual fields. Neither GBZ nor VGB affect glare sensitivity.