PURPOSE: to determine the prevalence of astigmatism and the change of the axis according to the age in an ophthalmology private clinic population in the city of Florianópolis, Santa Catarina, Brazil. METHODS: A retrospective, descriptive, cross-sectional study was carried out based on the analyses of medical files. Astigmatism was classified as a cylindrical equivalent <-0,5 diopter (D). Astigmatism with the rule was defined as 160° to 20° , oblique astigmatism as 21° to 69° and 111° to 159° , and astigmatism against the rule when axes were located from 70° to 110° . The basis were presented and analyzed according to the glasses prescription. RESULTS: There were found 20866 astigmatic eyes (47,6% - 95% Confidence Interval CI - 47,1-48). The astigmatism axis was with the rule in 9574 eyes (45,9% CI 95% 45,2-46,6), oblique in 3893 eyes (18,7% CI 95% 18,1-19,2), and against the rule in 7399 eyes (35,5% CI 95% 34,8-36,1). It was verified the prevalence of the oblique axis remains stable with the age, while there is an inversion in the cylindric axis from with the rule to against the rule as time goes by. CONCLUSION: This study has made evident the change in the axis according to the age. It was not found any relation between the degrees of the ametropy and the axis of the astigmatism.
Astigmatism; Prevalence; Age distribution; Eyeglasses; Refractive errors; Visual acuity
