Objective: To investigate the vision distribution and the leading cause of blindness in farmer aged >or= 50 years in Doumen county.
Methods: Cluster sampling size was estimated within an error bound of 0.35% with 95% confidence limit, 1.25 design effect and 85% response rate. Presenting visual acuity was measured by ETDRS (early treatment diabetic retinopathy study) tumbling chart. Eye examinations of external eye, anterior chamber, lens, fundus and intraocular pressure were carried out by ophthalmologists. A diagnosis of the principal cause for all the eyes with presenting visual acuity less than 0.3 was made as well. The field survey was conducted by two teams after pilot agreement testing.
Result: 5,342 individuals were examined in 36 sampling units. The prevalence of blindness was five-fold in the group aged >or= 70 years than in the group 50 - 59 years. The rate of blindness in the group with less education was higher than the group with 5 years schooling. The leading causes of blindness were cataract (44.90%), cornea opacity (16.36%), globe disorders (10.76%), refractive error (7.08%) and glaucoma (5.88%).
Conclusions: The prevalence of blindness and low vision was 2.67% and 19.91%, respectively in farmers aged >or= 50 years. The leading cause of blindness was cataract.