Table 1_Impact of smoking exposure on meibomian gland morphology and tear film stability: a cross-sectional study.docx

PurposeTo investigate the effects of smoking on the structure and function of the meibomian glands.
MethodsA 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.
ResultsThe gland dropout area demonstrated the strongest positive correlation with smoking index (β = 0.449, p < 0.001). The number, height, and width of meibomian glands were negatively correlated with smoking index (β = −0.258, p = 0.002; β = −0.192, p = 0.021; β = −1.176, p = 0.036, respectively). Furthermore, the eyelid margin morphology score and meibum secretion function worsened with increasing smoking index (B = 0.002, OR = 0.998, 95% CI: −0.001 to 0.003, p < 0.001, B = −0.002, OR = 0.998, 95% CI: −0.001 to −0.002, p < 0.001). Tear film stability showed negative correlations with smoking index (β = −0.245, p = 0.003).
ConclusionIncreased 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.