The effect of smoking on dry eye disease and corneal thickness in the Saudi population: a cross-sectional study

Purpose: To investigate the impact of smoking on ocular surfaces, tear film, and central corneal thickness (CCT) in the Saudi population. 

Methods: This cross-sectional, quantitative study was conducted among adults in two cities in the Kingdom of Saudi Arabia (KSA). Participants were selected using random sampling from two university communities in both cities. Participants were classified into 3 groups (nonsmokers, passive and active smokers) and clinical measurements of tear film stability and integrity, and central corneal thickness were assessed including sociodemographic characteristics. 

Results: The study involved 305 individuals, aged 27 years (SD = 5), mostly residing in Al-Baha (61.3%), with 96.1% having normal vision. Most of the participants (75.7% and above) had normal tear function and stable tear film. There were significant weak negative correlations between increasing age and lower Schirmer scores (R = − 0.2, P < 0.001) and lower tear meniscus height (R = − 0.17, P < 0.05). Smoking status was significantly associated with sex and age (P < 0.001) with increase in age increasing smoking status. Significant differences in dry eye disease classification (Schirmer test, tear meniscus height, and non-invasive keratograph break-up time) were observed based on smoking status, but no association was found with central corneal thickness (CCT). After adjusting for age and sex, dry eye disease classification remained significantly different across smoking statuses (P < 0.001). Also, there were significant associations between cigarette smoking and various dry eye disease indicators and symptoms except eye fatigue (P < 0.05). 

Conclusion: This study revealed a significant association between sex and increasing age with smoking-related DED symptoms. Active smokers, particularly males and older individuals, reported higher prevalence and severity of DED symptoms, along with unstable and reduced tear film quality. These findings highlight the need for public health interventions to raise awareness about the ocular risks of smoking.