Sildenafil (PDE5 inhibitors) and Non-arteritic anterior ischaemic optic neuropathy (NAION): is the FAERS signal real?
Sildenafil (PDE5 inhibitors) ↔ Non-arteritic anterior ischaemic optic neuropathy (NAION)
Sildenafil and related PDE5 inhibitors have been linked to non-arteritic anterior ischaemic optic neuropathy (NAION), a sudden painless loss of vision from reduced blood flow to the optic nerve. This prompted an FDA label update in 2005; the association is debated and partly confounded by vascular risk factors that are common in the men who use the drug, so it is best described as an uncommon, plausibly drug-associated event rather than a certainty. The 90 co-reports (PRR 9.4) reflect both the signal and the difficulty of separating drug effect from background vascular risk.
Regulatory basis: sildenafil prescribing information (FDA 2005 label change on NAION; caution in patients with NAION history).
| Bradford Hill viewpoint | Status | Note |
|---|---|---|
| Temporality (necessary) | met | Vision loss occurs in a temporal relationship to use in case reports |
| Strength | partial | PRR 9 on a small co-report count — a modest signal for a rare event |
| Consistency | met | Case reports and observational studies, but with confounding by shared vascular risk |
| Specificity | met | A recognised drug-associated optic event, though other causes exist |
| Biological gradient | partial | Not clearly dose-related |
| Plausibility | met | Reduced optic-nerve perfusion is the proposed mechanism |
| Coherence | met | Coheres with the FDA label change and caution in at-risk patients |
| Experiment | partial | Observational and confounded; no randomized trial |
| Analogy | met | Analogous to NAION attributed to other vasoactive drugs |
This page's own qualitative read, not an automated/citation-gated assessment.