Abstract
Purpose: :
To use wide field multifocal electroretinography (WF mfERG) to determine the incidence of retinal dysfunction in people with epilepsy on vigabatrin and other GABA–ergic drugs and to evaluate WF mfERG as an alternative to traditional perimetry.
Methods: :
A long term longitudinal study has been completed to objectively assess the progression of neuro–retinal toxicity associated with long–term VGB therapy in 180 patients, 99 of whom have had repeat assessments.Patients were recruited in the following groups. Group 1: patients were on VGB for at least 2 years, Group 2: patients were on VGB for at least two years and off VGB for at least 2 years, Group 3: patients have never been on VGB but were on an antiepileptic drug which had a GABA–ergic action and Group 4: patients have never been on any drugs with a GABA–ergic action. All patients had WF mfERG, logMar visual acuity, colour vision assessment, static perimetry and ISCEV standard ERG. In addition visual quality of life and epilepsy–related quality of life were assessed using questionnaires VFQ–25 and QUOLIE –31 respectively.
Results: :
The incidence of bilateral visual field defects is high in all groups tested, even those not on VGB (Group 1: 65%, Group 2: 46%, Group 3: 30% and Group 4: 21%). The difference in P1 latency between central and peripheral responses on WF mfERG corresponds to a selective peripheral retinal toxicity,The incidence of retinal toxicity in patients on VGB using the WF mfERG is 52.7% and 22% in Group 2. The incidence of retinal toxicty in Group 3 and 4 was 0%.
Conclusions: :
The WF mfERG is the most sensitive and specific tool we have to monitor VGB associated neuro–retinal toxicity.
Keywords: electrophysiology: clinical • drug toxicity/drug effects • clinical (human) or epidemiologic studies: prevalence/incidence