Studying the prevalence of astigmatism and its related factors in underprivileged rural areas in Iran

Using random cluster sampling, two rural areas in the north and southwest of Iran were randomly selected, and 3851 persons over 1 year of age were invited to the study. In addition to recording demographics, retinoscopic refraction was conducted using auto-refraction results, and cycloplegic refraction was done for people under 20 years. The prevalence of astigmatism was determined based on cylinder error cut-off points of 0.5 diopter (D), 1.0D, 2.0D and 3.0D. To assess variables’ relationship with astigmatism, multiple logistic regression was used

The prevalence of astigmatism as a cylinder error greater than 0.5D was 35.61% (95% CI: 33.66-37.56); this was 33.98%(95% CI:31.39-36.57) in women and 36.91%(95% CI: 33.9-39.92) in men. The lowest prevalence was seen in the 6 to 20 year old age group (13.57%) and the highest prevalence was found in individuals older than 70 years (82.46%). In the multiple logistic regression model, age and education level were significantly related to astigmatism. The prevalence rates of with-the-rule (WTR), against-the-rule (ATR), and oblique astigmatism were respectively 14.98%, 17.18%, and 3.45%. The prevalence of WTR astigmatism decreased with age, while the prevalence of ATR and oblique astigmatism-to a lesser extent-increased. In the multiple logistic regression model, age, education level, and place of residence significantly related to the type of astigmatism

The prevalence of astigmatism was not much different from previous studies; however, there were considerable age-related changes, and we observed different prevalence rates in different age groups. The prevalence of astigmatism in elderly people is substantial and can be of concern. Northern and southwestern rural areas differed by types of astigmatism based on axis orientation, which can be a genetic or environmental effect