In a survey of 426 patients of Toronto ophthalmologists the correlations of reported smoking habits with (1) intraocular pressure and (2) visual acuity were examined. Average tonometer readings were closely similar in smokers, ex-smokers, and non-smokers, and multiple regression analysis showed similar age coefficients for the 3 categories. However, in women (but not in men) there was also a significant coefficient related to total cigarette exposure (puff-pack-years). It is suggested that this was due to recent smoking rather than a permanent effect on tonometer pressures, pointing the need to standardise this aspect of ocular pressure measurements. Visual acuity showed similar age coefficients in smokers, ex-smokers, and non-smokers, with no independent effect of exposure to cigarette smoke.