Association of lipid layer patterns with tear evaporation in smokers, refractive errors, and high body mass index

The stability of the tear film is essential for ocular health. Smoking, refractive errors (RE), and a high body mass index (BMI) are key risk factors for dry eye disease. Dry eye symptoms may be caused by a high tear evaporation rate (TER) and/or a thin lipid layer.

To assess the correlation between TER and lipid layer patterns (LLP) within 4 distinct groups: healthy controls, smokers, subjects with RE, and individuals with high BMI.

The study included 120 subjects aged 18-30 years divided into 4 groups (30 per group; 15 women and 15 men). The ocular surface disease index (OSDI) was assessed, followed by evaluation of LLP using EASYTEAR View+ and TER using the Delfin VapoMeter.

Kruskal-Wallis tests revealed significant between-group differences in OSDI (χ2 = 62.91, n = 120, p < 0.001) and LLP (χ2 = 26.59, n = 120, p < 0.001), but not in TER (χ2 = 7.20, n = 120, p = 0.066). Within-group Kendall tau-b correlations between TER and LLP revealed strong negative associations in the high-BMI (τb = -0.563, n = 30, p < 0.001) and smoker groups (τb = -0.457, n = 30, p = 0.002). A moderate negative correlation was found in the RE group (τb = -0.287, n = 30, p = 0.043), but not in healthy controls (τb = -0.199, n = 30, p = 0.189).

The association between TER and LLP was strongly negative in smokers and the high-BMI group, moderate in the RE group, and absent in healthy controls. The inverse relationship between TER and LLP may indicate compromised tear film stability in populations at risk of dry eye disease.