Abstracts

Rationale: The objective of the study was to compare the relative prevalence of adverse visual side effects (AVSE) among both older and newer antiepileptic drugs (AEDs). Methods: As part of the Columbia/Yale AED Database Project, we reviewed patient background, medical history, AED use, efficacy, side effects, and dose and medication changes for 2188 adult patients newly started on an AED (age ≥ 16). AVSEs included blurred vision, diplopia, glaucoma, oscillopsia, visual field deficits, and visual acuity decrease. Rate of AVSE attributed to each AED was compared to the rate of AVSE attributed to all other AEDs. Rates of intolerability (e.g. AVSEs that led to reduction in drug dose or discontinuation) were also compared. Results: Overall, AVSEs occurred in 7.9% (172/2188) of patients. 5.0% (110/2186) of patients reduced AED dose as a result of AVSE(s), while 0.6% (14/2186) discontinued the AED blamed. Seizure clusters [p < 0.001; OR, 2.60 (1.75-3.86)], polytherapy [p < 0.004; OR, 1.86 (1.23-2.82)] and secondary generalized seizures [p < 0.001; OR, 2.59 (1.74-3.86)] were found to be significant predictors of AED-attributed AVSEs in multivariate analysis. When we controlled for these three predictors, we found that lamotrigine (8.7%, n=1113), oxcarbazepine (9.6%, n=239), felbamate (9.7%, n=72), and carbamazepine (6.6%, n=303) had significantly greater rates of AVSE compared to other AEDs (all p < 0.05). Oxcarbazepine (5.9%), lamotrigine (5.4%) and carbamazepine (4.6%) led to significantly more dose reductions compared to other AEDs, and lamotrigine (0.6%) led to significantly more discontinuations (all p < 0.05). Specifically, higher incidences of blurred vision were observed in patients taking lamotrigine (4.9%) and oxcarbazepine (4.2%). Higher incidences of diplopia were associated with carbamazepine (4.0%), lamotrigine (4.1%), and oxcarbazepine (5.4%). The only case of glaucoma was attributed to topiramate intake, and the patient discontinued the drug as a result of this. 10 cases of oscillopsia were reported, 3 of these cases were attributed to lamotrigine, 2 cases were attributed to oxcarbazepine, and 1 case was attributed to lacosamide, phenobarbital, phenytoin, tiagabine, and zonisamide individually, but no significant correlations were seen. Vigabatrin was more commonly associated with visual field deficits (6.1%) and visual acuity decrease (1.2%, both p < 0.05) compared to other AEDs. However, these findings may be biased since patients taking vigabatrin were recommended by physicians to have regular eye examinations, and cases of visual field deficits associated with vigabatrin were determined through visual field testing. Pregabalin (1.1%, n=282), levetiracetam (1.1%, n=884), and clobazam (1.1%, n=187) had three of the lowest AVSE rates, and individually, they were significantly lower compared to other AEDs (all p < 0.05). Conclusions: Conclusion: There is significant variability between AEDs in terms of their AVSE profiles. AVSEs appear to occur more frequently in patients taking lamotrigine, carbamazepine, and oxcarbazepine than other AEDs, particularly blurred vision and diplopia.