Prolonged Face Mask Wearing Worsens Self-Reported Dry Eye Symptoms during the COVID-19 Pandemic in Dental Healthcare Practitioners

**Background:** Dry eye disease (DED) is a common multifactorial ocular surface disorder affecting 20-50% of the global population. During the COVID-19 pandemic, widespread mandatory face mask use led to reports of mask-associated dry eye (MADE), attributed to upward airflow from loosely fitted masks increasing tear evaporation. Dental healthcare practitioners are at particular risk due to prolonged daily mask use. This study aimed to evaluate the prevalence and risk factors of self-reported MADE among Croatian dentists.

**Methods:** An anonymous online questionnaire was distributed via email to 1000 registered dentists in Croatia from February to August 2022. The survey collected demographic data (age, gender, region), mask-wearing duration (at work and total daily), use of personal protective equipment (visors, glasses), contact lens use, history of eye surgery, current medications, and prior DED symptoms. Subjective dry eye symptoms were assessed using a modified Ocular Surface Disease Index (OSDI) questionnaire, where each question was appended with "while wearing a face mask." OSDI scores range from 0 (normal) to 100 (severe dry eye); symptomatic DED was defined as OSDI >22. MADE was defined as new onset or worsening of pre-existing DED symptoms while wearing a face mask. Statistical analyses included Mann-Whitney U test, Kruskal-Wallis test, chi-square test, and univariable and multivariable logistic regression.

**Key Results:** A total of 405 dentists responded (response rate 40.5%). The majority were female (75.6%) and younger than 40 years (56.5%). Overall prevalence of MADE was 29.1% (95% CI: 24.7-33.6); 11.1% had deterioration of previous DED and 18% had new-onset DED while wearing a mask. Prevalence of previous DED (without mask-related worsening) was 12.1% (95% CI: 9.1-15.8). The median OSDI score for all participants was 10.42 (IQR 2.08-27.08). Participants who wore masks >6 hours/day at work had significantly higher OSDI scores (median 12.5, IQR 4.17-29.17) compared to those wearing masks <6 hours/day (median 8.33, IQR 0-22.92; p=0.040). For total daily mask use >6 hours, OSDI was higher (12.5 vs. 6.25) but not statistically significant (p=0.066). Multivariable logistic regression identified two independent risk factors for MADE: age >61 years (OR 3.522, 95% CI 1.448-8.563, p=0.05) and wearing a face mask >6 hours at work (OR 1.779, 95% CI 1.017-3.113, p=0.044). Female gender, antihypertensive use, and total daily mask use >6 hours were significant in univariable but not multivariable analysis.

**Clinical Implications:** This study demonstrates that prolonged face mask use (>6 hours/day at work) is significantly associated with higher OSDI scores and increased risk of MADE among dental healthcare practitioners, with an overall MADE prevalence of 29.1%. Older age (>61 years) further elevates risk. These findings underscore the importance of recognizing MADE as an occupational hazard for dentists and other healthcare workers who wear masks for extended periods. Clinicians should consider advising patients on proper mask fitting (e.g., taping the upper border) to reduce upward airflow, encourage regular breaks from mask wearing when safe, and recommend artificial tears or lubricating eye drops for symptomatic relief. Future studies should incorporate objective clinical tests (e.g., tear film break-up time, Schirmer test) and examine mask type (surgical vs. N95) to further elucidate mechanisms and preventive strategies.