← All causality assessments
Causality: well established
Causality assessment · Causality: well established
Vigabatrin and Visual field defect: is the FAERS signal real?
A written Bradford Hill assessment of one drug–event pair. The grade is a judgement about the signal, not a statement that this drug causes this event in any one person; FAERS counts are reports, not rates.
Vigabatrin ↔ Visual field defect
n=141 co-reports · PRR 28.8 · ROR 29.1
Vigabatrin is an irreversible GABA-transaminase inhibitor for infantile spasms and refractory epilepsy; it causes a characteristic, often irreversible concentric visual-field defect, appearing here as 141 co-reports (PRR 28.8). Risk rises with cumulative dose and duration, so the label requires baseline and periodic visual-field testing and limits use where benefit does not clearly outweigh the risk.
Regulatory basis: vigabatrin (Sabril) prescribing information — boxed warning for permanent vision loss; mandatory visual-field monitoring.
| Bradford Hill viewpoint | Status | Note |
|---|---|---|
| Temporality (necessary) | met | Field loss after months of therapy |
| Strength | met | PRR 28.8, large |
| Consistency | met | Reproduced across cohort studies |
| Specificity | met | Fairly specific to vigabatrin |
| Biological gradient | met | Cumulative dose-related |
| Plausibility | met | GABA accumulation and retinal toxicity |
| Coherence | met | Fits the mechanism |
| Experiment | met | Cohort and monitoring data support it |
| Analogy | met | Analogous to other retinotoxic drugs |
This table is this page's own qualitative read of the literature cited above, not an automated or citation-gated assessment — see the note at the bottom of this page.
✗ No ClinicalTrials.gov results-posting trial in the top search hits for vigabatrin captured visual field defect as a tracked adverse event in a usable structure. Visual-field defects develop insidiously over months and need perimetry to detect, so epilepsy trials did not capture them as coded events.