Changes in the ERG d-wave with vigabatrin treatment in a pediatric cohort
Rachel Dragas1, Carol Westall, Tom Wright
1Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, Canada.
Insights
The cone d-wave electroretinogram (ERG) response can indicate retinal toxicity in infants treated with Vigabatrin (VGB). Reduced d-wave amplitude suggests Vigabatrin-associated ERG reduction (VAER), a marker for VGB toxicity.
Area of Science:
- Ophthalmology
- Pediatric Neurology
- Toxicology
Background:
- Vigabatrin (VGB) is a key treatment for infantile spasms (IS), a severe childhood epilepsy.
- VGB treatment is linked to visual field constriction, necessitating alternative monitoring methods in infants.
- Electroretinograms (ERGs) are utilized to assess visual function in infants, serving as a proxy for visual field testing.
Purpose of the Study:
- To investigate the utility of the d-wave ERG response as a marker for Vigabatrin-associated ERG reduction (VAER) in infants.
- To evaluate if changes in the d-wave ERG amplitude correlate with retinal toxicity in children undergoing VGB treatment.
Main Methods:
- One hundred children with IS treated with VGB were included.
- The cone-OFF response, specifically the d-wave ERG, was elicited using a long flash stimulus.
- Fifty-one patients with baseline and follow-up ERG data were analyzed for VAER, with d-wave amplitude manually measured.
Main Results:
- A longer duration of VGB treatment correlated with reduced d-wave amplitude.
- Nine patients developed VAER during the study.
- Infants with VAER exhibited significantly reduced d-wave amplitudes compared to those without VAER.
Conclusions:
- Reduction in the cone d-wave ERG amplitude may serve as an indicator of Vigabatrin-associated retinal toxicity.
- The d-wave ERG shows potential as a sensitive biomarker for monitoring VGB-induced retinal changes in infants.
Purpose:
Vigabatrin (VGB), a treatment for the childhood epilepsy, infantile spasms (IS), is implicated in visual field constriction. Electroretinograms (ERGs) are used as a substitute for visual field testing in infants. We use the VGB-associated ERG reduction (VAER), defined as reduction in age-corrected light adapted 30 Hz flicker amplitude from a pre-treatment measurement in the absence of other retinal defects, as an indicator of retinal toxicity resulting from VGB use. The d-wave ERG response is predominantly the result of OFF-bipolar cell depolarization response to light offset. The purpose of this study is to evaluate the ERG d-wave response as a marker for VAER toxicity in an infant population.
Methods:
One hundred children with IS treated with VGB (median age at baseline: 7.6 months; range 1.7-38.4) were tested for the cone-OFF response elicited to a 250 cd s m(2) flash with 200 ms duration (long flash ERG). Diagnosis of VAER requires baseline testing of the flicker ERG and at least one follow up ERG; Fifty-one patients fulfilled this criteria. Fifty-eight children received the long flash ERG at baseline. Thirteen retinally normal controls with a median age of 32 months (5.7-65) were also tested. Amplitude and implicit time of the d-wave response were measured manually.
Results:
Longer duration of treatment was associated with reduced d-wave amplitude (ANOVA p < 0.05) in patients taking VGB. Nine patients demonstrated VAER during the course of the study. D-wave amplitude was reduced in the IS group with VAER compared to those without VAER (p < 0.05).
Conclusions:
Vigabatrin associated retinal defects may be reflected in reduction of the cone d-wave amplitude.
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