Reza Jafari - Department of Ophthalmology, Faculty of Medicine, Mazandaran University of Medical Sciences, Sari, Iran.
Mohammad Hossein Hasanzadeh - Department of Medicine, Faculty of Medicine, Mazandaran University of Medical Sciences, Sari, Iran.
Ahmad Ahmadzadeh Amiri - Department of Ophthalmology, Bu Ali Sina Hospital, Mazandaran University of Medical Sciences, Sari, Iran.
Samira Heydarian - Department of Rehabilitation Sciences, School of Allied Medical Sciences, Mazandaran University of Medical Sciences, Sari, Iran.
Fahimeh Ghasemi Charati - Department of Medical Surgical Nursing, Nasibeh Faculty of Nursing and Midwifery, Mazandaran University of Medical Sciences, Sari, Iran.

Background: Refractive errors are among the most common causes of vision loss in patients attending healthcare facilities in the first and second decades of life. Astigmatism stands out as one of the common and treatable causes of vision loss in pediatrics.  Methods: In this cross-sectional study, the samples were chosen by random cluster sampling among children aged between ۷ and ۱۳ years from elementary schools in ۲۰۱۴-۲۰۱۵ academic year. For all students, refractive errors were assessed by Autorefractor Keratometer and retinoscopy. Internal astigmatism was defined as the difference between refractory and corneal astigmatism. SPSS software, version ۱۶ was used for data analysis. Results: A total of ۱۰۰۹ children participated in the study. Among them, ۴۶۸(۴۶.۴%) were male, and ۵۴۱(۵۳.۶%) were female. Their mean age was ۹.۲±۱.۷ years. About ۱۴.۵% of them had refractory astigmatism. Corneal astigmatism was the most common type, with ۱۲.۵% of students suffering from it. The prevalence of corneal astigmatism was not significantly different between males and females (P=۰.۱۹). Also, there was no significant relationship between increasing age and prevalence of astigmatism in this age group (P=۰.۰۶). Conclusions: There was no significant difference in the rate of refractory astigmatism, lenticular and corneal astigmatism, between males and females. Because correcting refractory errors in students has a positive effect on learning ability and physical and mental development, screening and follow-up are recommended in this age group.

Astigmatism, Corneal astigmatism, Lenticular astigmatism, Prevalence