Human cataract risk factors: significance of abstention from, and high consumption of, ethanol (U-curve) and non-significance of smoking.

Current ethanol consumption and cigarette smoking were quantified by questionnaire in Edinburgh and suburbs, Scotland, UK. Stringently matched cataract-control pairs (n = 990 and 858, respectively) were included. For ethanol, 'light and infrequent' consumption and 'light and frequent' were associated with a significantly lower risk of cataract than were total abstention and 'occasional' consumption; the prevalence of cataract rose with further increases in consumption, suggesting a U-shaped curve. For nuclear cataract, white in particular, there is a significant trend with amount consumed. Smoking was not found to be a risk factor.