Effects of smoking on tear film and ocular surface.

This study was performed to evaluate the changes of tear film and ocular surface caused by smoking. Symptom scoring, tear film break-up time (BUT), basal tear secretion test, corneal sensitivity test, keratoepitheliopathy scoring, and conjunctival impression cytology were performed in 29 smokers (58 eyes) and 26 non-smokers (52 eyes). Tear film BUT, basal tear secretion, corneal sensitivity, and squamous metaplasia were 7.71+/-2.66 sec, 6.29+/-2.85 mm, 53.69+/-5.69 mm, and 2.45+/-1.26 in smokers and 9.62+/-3.14 sec, 10.04+/-3.87 mm, 56.46+/-4.79 mm, and 1.12+/-0.83 in non-smokers, respectively (p<0.05). Symptom score, keratoepitheliopathy score, and goblet cell density were not significantly different between the two groups. Tear film BUT was shorter, basal tear secretion and corneal sensitivity were lower, and squamous metaplasia was higher in heavy smokers than in light smokers. In conclusion, smoking deteriorates the tear film and ocular surface with decreased quantity and quality of tear film, decreased corneal sensitivity, and squamous metaplasia, and this deterioration is related to the amount of smoking.