Objectives: To estimate the prevalence of floppy eyelid syndrome (FES) and to determine the associated factors in a representative sample of Iranian adult population aged 45 to 69 years.

Methods: The data were according to the second phase of Shahroud Eye Cohort Study performed in 2014 with 4,737 participants aged 45 to 69 years. Diagnosis of FES was made based on the clinical judgment of the ophthalmologist during ocular examinations. The percentage and confidence intervals (CIs) of the prevalence of FES were reported, and the associated factors were analyzed using simple and multiple logistic regression models.

Results: In this study, 11.3% of the participants (6.7% of men and 14.6% of women) had FES in at least 1 eye. The prevalence of FES decreased with age. Floppy eyelid syndrome grades 1, 2, and 3 were observed in 72.8%, 21.6%, and 0.6% of the participants, respectively. Although the relationship between age and FES was not significant in men (odds ratio (OR)=0.98, 95% CI: 0.95-1.01), the odds of FES decreased significantly with an increase in age in women (OR=0.94, 95% CI: 0.92-0.96). Body mass index ≥25 (OR=1.65, 95% CI: 1.25-2.18), meibomian gland dysfunction (OR=1.47, 95% CI: 1.18-1.81), and hypertension (OR=1.84, 95% CI: 1.46-2.31) had significant associations with FES.

Conclusion: The prevalence of FES was 11.3%, and 72.8% of the participants had grade 1 FES. Significant associations were found between FES and other eyelid disorders. Floppy eyelid syndrome was more prevalent in younger women.