Vigabatrin Effects on Visual Function and Imaging

Vigabatrin is an antiepileptic agent that irreversibly inhibits γ-aminobutyric acid transaminase, thereby elevating central GABA levels and suppressing seizure activity. Despite its efficacy in infantile spasms and refractory focal seizures, vigabatrin is uniquely associated with peripheral visual field constriction and retinal toxicity. Clinical assessment of vigabatrin-related ocular effects employs visual field perimetry, electroretinography and optical coherence tomography (OCT) to detect functional and structural changes in the retina and optic nerve. Imaging studies demonstrate thinning of the peripapillary retinal nerve fibre layer and macular layers, correlating with the severity and duration of exposure. Preclinical work indicates preferential accumulation of the active enantiomer in the retina and visual cortex, with light exposure and phototransduction pathways contributing to toxicity. Emerging evidence examines genetic susceptibility to retinal nerve fibre layer thinning and explores whether rare variants underlie individual risk. The global challenge lies in balancing seizure control against potential visual impairment. Optimised monitoring protocols, personalised dosing strategies and refinements in imaging biomarkers aim to mitigate ocular risk while preserving therapeutic benefit.

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A pharmacogenomic investigation in individuals exposed to vigabatrin assessed common genetic variation as predictors of peripapillary retinal nerve fibre layer thinning. Quantitative genome-wide analyses and polygenic risk scoring using OCT measurements found no large‐effect common variants, suggesting that rare genetic factors may be more relevant to vigabatrin-induced visual field loss.

A large retrospective review of children receiving vigabatrin for infantile spasms reported a low incidence of definite ocular toxicity in routine ophthalmic examinations. Electrophysiological testing identified two cases of vigabatrin-related retinal dysfunction, while optical coherence tomography and formal perimetry yielded few attributable abnormalities, underscoring challenges in screening young patients and the need to refine paediatric monitoring strategies.

A comprehensive narrative review of peripheral visual field defects in paediatric epilepsy patients on vigabatrin collated data on mechanisms, risk factors and pharmacokinetics. It highlighted inner retinal toxicity via GABA-C receptor inhibition, the influence of cumulative dose, duration of therapy, age and sex, and the modifying role of light exposure. The review emphasised the necessity of weighing seizure control against potential visual sequelae and engaging caregivers in risk–benefit discussions.

Vigabatrin Effects on Visual Function and Imaging publication trend

The graph below shows the total number of articles in vigabatrin effects on visual function and imaging across all publications each year (not limited to Nature Index journals).

Technical terms

Peripapillary retinal nerve fibre layer (ppRNFL): The annular band of nerve fibres surrounding the optic disc, measured by OCT to assess optic nerve health.

Optical coherence tomography (OCT): A non-invasive imaging modality that generates high-resolution cross-sectional images of retinal layers.

Electroretinogram (ERG): An electrophysiological test recording retinal electrical responses to light stimuli, indicating photoreceptor and inner retinal function.

Visual field perimetry: A functional assessment mapping the extent and sensitivity of a patient’s peripheral vision.

GABA transaminase: The enzyme responsible for GABA degradation; its inhibition by vigabatrin leads to increased inhibitory neurotransmission.

References

1. Testing for pharmacogenomic predictors of ppRNFL thinning in individuals exposed to vigabatrin. Frontiers in Neuroscience (2023).
2. Ocular examinations, findings, and toxicity in children taking vigabatrin. Journal of American Association for Pediatric Ophthalmology and Strabismus (2022).
3. Peripheral visual field defect of vigabatrin in pediatric epilepsy: A review. The Egyptian Journal of Neurology, Psychiatry and Neurosurgery (2023).
4. Preclinical tissue distribution and metabolic correlations of vigabatrin, an antiepileptic drug associated with potential use‐limiting visual field defects. Pharmacology Research & Perspectives (2019).
5. Vigabatrin-Induced Retinal Toxicity Is Partially Mediated by Signaling in Rod and Cone Photoreceptors. PLOS ONE (2012).