Transient effects of smoking on the eye

Abstract

Purpose To investigate the immediate short-term effects of smoking in habitual smokers, on the tear film, pupil size and accommodative ability of the human eye. Methods Habitual smokers were tested within 5 min of smoking a cigarette. The tear film analysis was undertaken using tear break–up time (TBUT), tear lipid layer thickness and tears meniscus height (TMH) measurements. Three different ways of tear break–up time (TBUT) were used; using fluorescein; a non-invasive TBUT using tearscope; and a video captured method with a corneal topographer. Pupil size was measured objectively using the video capture on the corneal topographer. Accommodative ability was checked by performing a ‘push up test' to measure amplitudes of accommodation (AoA) and by measuring defocus curves. Results Forty-five participants were enrolled (mean age 22.0 ± 4.4 years). TBUT was reduced after smoking a cigarette with all three assessment methods and this reduction was statistically significant (p < 0.001). A reduction in lipid layer thickness was seen after smoking a cigarette with both methods used and was statistically significant (p < 0.01). A significant reduction in pupil size (p < 0.01) and in AoA (p < 0.001) was observed after smoking a cigarette. The difference in TMH and defocus curves, before and after smoking, were not statistically significant (p > 0.05). Conclusion The study shows that there is an immediate adverse effect of smoking on TBUT and AoA which seems to be very transient.