Impact of smoking exposure on meibomian gland morphology and tear film stability: a cross-sectional study.

Purpose: To investigate the effects of smoking on the structure and function of the meibomian glands. Methods: A total of 104 chronic smokers (with a smoking history of more than 5 years) and 44 healthy non-smokers were included. Based on smoking index, participants were categorized into four groups: non-smoking, mild, moderate, and heavy smoking. Meibomian gland images were compared across groups to assess morphological features, including defect area, number, height, and width. Furthermore, eyelid margin morphology, meibum characteristics and quantity, as well as tear film breakup time (TBUT), were evaluated to further investigate the impact of smoking on the structure and function of the meibomian glands. Results: The gland dropout area demonstrated the strongest positive correlation with smoking index ( Conclusion: Increased smoking exposure is strongly associated with deleterious structural and functional alterations of meibomian glands. Increased smoking exposure is associated with more severe meibomian gland morphological damage, worsened eyelid margin signs, reduced meibum quality and quantity, and accelerated deterioration of tear film stability. The underlying mechanisms may involve oxidative stress and chronic inflammation induced by tobacco smoke. For the management of smoking-related meibomian gland dysfunction (MGD), smoking cessation should be advised along with targeted anti-inflammatory or antioxidant treatments.