Frequent Smoking May Alter Corneal Biomechanical Parameters

Corneal stiffening may result from frequent smoking, particularly in individuals with a body mass index (BMI) of 24 or higher, according to a study published in Eye. Smoking less than 15 minutes per day and consuming alcohol, however, was not associated with any changes in corneal biometry, the report shows.

Researchers enrolled 1645 students (mean age, 19.0 years; 68.6% women) in a university-based study and interviewed participants to determine demographic factors, medical history, eye rubbing habits, and smoking and alcohol consumption behaviors. Participants underwent non cycloplegic refraction, BMI measurements, and assessment of a total of 10 corneal biomechanical parameters using dynamic Scheimpflug imaging. 

Among the cohort, 116 (7.1%) students were smokers, 320 (19.5%) reported smoking for less than 15 minutes per day, and 291 (17.7%) had consumed alcohol in the past month. 

Smoking was significantly associated with a stiffer cornea, according to the report. Smokers demonstrated significantly slower second applanation velocity (A2v; β, 0.007 m/s; 95% CI, 0.001-0.014; P = .032) and lower integrated radius  (β, −0.214 mm⁻¹, 95% CI, -0.420 to -0.007; P = .043) compared with participants who did not smoke after adjusting for age, sex, eye rubbing, myopia, and BMI. 

Individuals who smoked and had a BMI of 24.0 or higher had slower A2v and lower integrated radius values compared with both participants who did not smoke and individuals who smoked and had a BMI less than 24.0. Alcohol consumption and passive smoking were not associated with corneal biomechanical parameters, the report shows.

Although the data may seem to suggest that corneal stiffening due to smoking may be a protective factor against keratoconus, the study authors highlight the effects of smoking on ocular pathology and suggest “encouraging university students to quit smoking could be essential to lower the prevalence of ocular disorders like glaucoma and its associated visual impairment and blindness, as well as the subsequent social and economic burden.”

Study limitations include a cross-sectional nature, the potential for recall bias, and ethnic homogeneity, which may limit the globalization of these findings.