Introduction: Studying the epidemiology of eye diseases in different populations helps both the individuals and ultimately the whole population to develop normal vision. The present study aims at determining the prevalence rates of impaired vision and their common etiology in the rural population of Sabzevar, Iran.

Methods: A population-based cross-sectional study was carried out on a number of 2508 samples, aged 3 days to 92 years old, from 40 clusters in Sabzevar. It took the study two years to be completed (i.e. March 2003 to March 2005). The subjects received preliminary visual screenings consisting of visual acuity test, retinoscopy and anterior segment examinations at the local clinics. Those with impaired vision were referred to a more specialized eye clinic for further comprehensive eye examinations, including visual acuity test using snelen E chart and refraction, slit-lamp biomicroscopy, applanation tonometery and dilated fundus examinations. Impaired vision was measured as a visual acuity of < 9/10 or as refractive errors of >0.5 diopter in either or both eyes.

Results: The subjects ranged from 3 days to 92 years old with the average age of 27.28 years and a standard deviation of 20.32. The prevalence rate of impaired vision was 32% (95% confidence interval [CI], 30.0-34.0). According to the study, refractive errors were the most common etiology of vision disorders rating at 28.30% (95% CI, 27-30.55), followed by cataract 6.0% (95% CI, 5.08-6.95), amblyopia 2% (95% CI,1.48- 2.58), strabismus 1.51% (95% CI,1.03-1.99), glaucoma 0.67% (95% CI,0.41-0.94) and nystagmus 0.5%( 95% CI,0.19-0.74).

Conclusions: Refractive errors, cataracts and amblyopia were the major causes of visual impairment in the rural population of Sabzevar. Recognizing common causes of visual impairment not only provide a chance for adequate treatment, but also it is necessary for the prevention of the disorders; thus, resulting in great personal, social, and economic benefits.