Effects of chronic smoking on central corneal thickness, endothelial cell, and dry eye parameters

Objective: To evaluate the effect of chronic cigarette smoking on dry eye parameters, endothelial cells, and corneal thickness. Design: Prospective cross-sectional case series. Methods: In this cross-sectional study, 49 eyes of 49 chronic smokers (smoker group) and 53 eyes of 53 age-matched, healthy non-smokers (non-smoker group) were enrolled. All participants underwent measurements of tear breakup time (TBUT), central corneal thickness (CCT) measurements with contact pachymeter and the Schirmer test with anesthesia. Corneal endothelial cells were evaluated by non-contact specular microscopy and photographed for analysis of cell density and hexagonality and the coefficient of variation in cell size. Results: The mean Schirmer score and TBUT value were significantly lower in the smoker group compared to the non-smoker group (p = 0.015) and p < 0.001, respectively). No statistically significant difference was found in the mean CCT, mean endothelial cell density, endothelial cell size, SD of size, and CV of size between smokers and non-smokers (p > 0.05). However, a lower percentage of endothelial hexagonal cells were observed in smokers than non-smokers (p < 0.001). Discussion and conclusion: Our results suggest that cigarette smoking seems to affect the Schirmer score, TBUT value, and hexagonal cells of the corneal endothelium.