Antidepressants, Mood Stabilizers, Antipsychotics, and the Risk of Cataract

Cataract is a common disease of the eye, and depression is common in patients with cataract. This raises the possibility that depression and the drugs used to treat depression may be risk factors for cataract. In a recent systematic review and meta-analysis of 7 case-control studies with a pooled sample of 447,672 cases and 1,510,391 controls, antidepressant drugs were associated with a very small but statistically significant increase in the risk of cataract; the odds ratios for different classes of antidepressants were in the 1.12-1.19 range. None of the 7 studies in the meta-analysis adjusted their analyses for confounding by indication. Furthermore, the meta-analysis results were characterized by unexplained high heterogeneity, and there was evidence suggestive of publication bias. These data, therefore, do not make a sufficient case for antidepressants being causal for cataract. Rather, the antidepressant data, along with data that associate mood stabilizer exposure with the risk of cataract, suggest that major mental illness and the correlates thereof may be a risk factor for cataract rather than the drugs that are used to treat these disorders. Surprisingly, in similar research designs, antipsychotic drugs were found either to have no effect or to protect against incident cataract. This indicates that the relationship between antidepressant exposure and cataract merits closer investigation, using research designs and analyses that better address confounding by indication. Examples for such research designs and analyses are provided. Until stronger evidence becomes available, a cause for concern remains unestablished.