Medical hypothesis discovery and innovation in ophthalmology

Abstract

Background: Dry eye disease is a multifactorial ocular-surface disorder. Tobacco smoke exposure has been associated with ocular discomfort and altered tear-film measures, although findings remain inconsistent. This study compared dry-eye symptoms and ocular-surface signs between tobacco smoke-exposed and non-exposed participants.
Methods: This cross-sectional reanalysis used a retrospective, de-identified dataset collected in Gaza in 2023. The sample comprised 81 participants: 40 tobacco smoke-exposed and 41 non-exposed controls. Exposure was defined by a pooled self-reported binary item encompassing cigarette smoking, shisha use, passive smoke exposure, or combinations thereof. Arab Ocular Surface Disease Index (Arab-OSDI) score was the primary outcome; tear break-up time (TBUT), Schirmer I test with topical anesthesia (STT), and corneal fluorescein staining (CFS) were secondary outcomes. All 81 records were analyzed with adjustment for sex and age category. Arab-OSDI, TBUT, and STT used ordinary least-squares regression with HC3 heteroscedasticity-consistent standard errors (SEs); CFS used proportional-odds ordinal logistic regression with HC3 covariance. Sensitivity analyses included median quantile regression for Arab-OSDI, log-transformed TBUT regression, and age-category frequency matching.
Results: Baseline age and sex distributions did not differ significantly between groups (P > 0.05 and P > 0.99, respectively). Mean (standard deviation [SD]) Arab-OSDI score was 17.18 (16.40) in the exposed group and 10.67 (10.53) in controls. After adjustment, exposure was associated with a 6.77-point higher Arab-OSDI score (HC3 SE, 2.96; 95% confidence interval [CI], 0.96 to 12.57; P < 0.05). Associations were not statistically significant for TBUT (regression coefficient [B] = -0.02 s; HC3 SE, 0.71; 95% CI, -1.41 to 1.37; P > 0.05) or STT (B = -0.55 mm; HC3 SE, 2.18; 95% CI, -4.82 to 3.73; P > 0.05). For CFS, the adjusted proportional-odds ratio for a higher staining category was 0.63 (95% CI, 0.18 to 2.18; P > 0.05). Median quantile regression for Arab-OSDI yielded B = 7.05 (95% CI, -0.23 to 14.33; P > 0.05), while regression of log-transformed TBUT yielded a ratio of 1.003 (95% CI, 0.775 to 1.299; P > 0.05). In the frequency-matched subset (N = 68), the adjusted Arab-OSDI difference was 6.82 points (95% CI, 0.09 to 13.56; P < 0.05).
Conclusions: Tobacco smoke exposure was associated with greater dry-eye symptom burden. No statistically significant associations were identified for TBUT, STT, or CFS. Arab-OSDI sensitivity estimates were similar in magnitude and direction, although the median-regression result was not statistically significant. Because exposure pooled cigarette smoking, shisha use, and passive smoke exposure, the findings cannot be interpreted as the isolated effect of active cigarette smoking. Future studies should distinguish these exposure modalities and quantify exposure intensity and duration.