High Prevalence of Refractive Errors in 7 Year Old Children in Iran.
BACKGROUND
The latest WHO report indicates that refractive errors are the leading cause of visual impairment throughout the world. The aim of this study was to determine the prevalence of myopia, hyperopia, and astigmatism in 7 yr old children in Iran.


METHODS
In a cross-sectional study in 2013 with multistage cluster sampling, first graders were randomly selected from 8 cities in Iran. All children were tested by an optometrist for uncorrected and corrected vision, and non-cycloplegic and cycloplegic refraction. Refractive errors in this study were determined based on spherical equivalent (SE) cyloplegic refraction.


RESULTS
From 4614 selected children, 89.0% participated in the study, and 4072 were eligible. The prevalence rates of myopia, hyperopia and astigmatism were 3.04% (95% CI: 2.30-3.78), 6.20% (95% CI: 5.27-7.14), and 17.43% (95% CI: 15.39-19.46), respectively. Prevalence of myopia (P=0.925) and astigmatism (P=0.056) were not statistically significantly different between the two genders, but the odds of hyperopia were 1.11 (95% CI: 1.01-2.05) times higher in girls (P=0.011). The prevalence of with-the-rule astigmatism was 12.59%, against-the-rule was 2.07%, and oblique 2.65%. Overall, 22.8% (95% CI: 19.7-24.9) of the schoolchildren in this study had at least one type of refractive error.


CONCLUSIONS
One out of every 5 schoolchildren had some refractive error. Conducting multicenter studies throughout the Middle East can be very helpful in understanding the current distribution patterns and etiology of refractive errors compared to the previous decade.
Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran; Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran, Iran.
Hassan
H
Hashemi
Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran.
Abbasali
A
Yekta
Department of Optometry, Iran University of Medical Sciences, Tehran, Iran.
Ebrahim
E
Jafarzadehpur
Refractive Errors Research Center, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran.
Hadi
H
Ostadimoghaddam
Department of Epidemiology, Faculty of Public Health, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Koorosh
K
Etemad
Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran, Iran.
Amir
A
Asharlous
Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran.
Payam
P
Nabovati
Department of Epidemiology, Faculty of Public Health, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Mehdi
M
Khabazkhoob
Cross-sectional study; Iran; Refractive errors