Prevalence of Myopia and Its Risk Factors in Urban School Children in Delhi: The North India Myopia Study (NIM Study)

Abstract

PurposeAssess prevalence of myopia and identify associated risk factors in urban school children.MethodsThis was a cross-sectional study screening children for sub-normal vision and refractive errors in Delhi. Vision was tested by trained health workers using ETDRS charts. Risk factor questionnaire was filled for children with vision <6/9.5, wearing spectacles and for a subset (10%) of randomly selected children with normal vision. All children with vision <6/9.5 underwent cycloplegic refraction. The prevalence of myopia <-0.5 diopters was assessed. Association of risk factors and prevalence of myopia was analyzed for children with myopia and randomly selected non myopic children and adjusted odds ratio values for all risk factors were estimated.ResultsA total number of 9884 children were screened with mean age of 11.6 + 2.2 years and 66.8% boys. Prevalence of myopia was 13.1% with only 320 children (24.7%) wearing appropriate spectacles. Mean myopic spherical error was -1.86 + 1.4 diopters. Prevalence of myopia was higher in private schools compared to government schools (p<0.001), in girls vs. boys (p = 0.004) and among older (> 11 years) children (p<0.001). There was a positive association of myopia with studying in private schools vs. government schools (p<0.001), positive family history (p< 0.001) and higher socio-economic status (p = 0.037). Positive association of presence of myopia was observed with children studying/reading > 5 hours per day (p < 0.001), watching television > 2 hours / day (p < 0.001) and with playing computer/video/mobile games (p < 0.001). An inverse association with outdoor activities/playing was observed with children playing > 2 hours in a day.ConclusionMyopia is a major health problem in Indian school children. It is important to identify modifiable risk factors associated with its development and try to develop cost effective intervention strategies.

Prevalence and associated factors of myopia among primary and middle school-aged students: a school-based study in Guangzhou

“…Although a prior study in Delhi reported that children in the upper-middle socioeconomic status had a slightly higher risk of myopia, 26 we did not find any significant association between family economic status and myopia in children in this study. Mutti's study 13 using subjects from the Orinda Longitudinal Study of Myopia illustrated that the association between myopia and school achievement as measured by the Iowa Tests of Basic Skills may be weak.…”

“…32 In addition, after incorporating all the significant variables (eg, gender, age, outdoor activity, and parental myopia) in the two-level logistic regression models 2 and 3, the final results demonstrated that reading for pleasure more than 2 h per day (AOR = 1.84, 95% CI = 1.09-3.12) was only positively associated with myopia in boys, and spending time watching television per week was only positively associated with myopia in girls. These results were consistent with Saw's study 23 showing that students who read more than 2 h per day were more likely to be myopia, Ip's study 33 reporting that longer time spent on reading for pleasure was associated with a myopic refraction, and Saxena's study 26 illustrating that positive association of myopia was observed with children study/ reading more than 5 h per day, watching television more than 2 h per day, and playing computer/video games. In addition, although many previous studies revealed that the distance of near work was associated with myopia in children, some of these studies only consider the distance of close-up reading was an important risk factor for myopia, 33,34 and others regarded the distances of different near work activities as a composite variable (distance from near work) and roughly thought that a higher prevalence of myopia was associated with shorter near work distance.…”

“…This definition was chosen to reduce the number of false-positive results for myopia, to reach a level of myopia likely to produce clinical symptoms, and to agree with the definition widely used in previous studies. [23][24][25][26][27] Subjects were further divided three refractive error groups based on their spherical equivalent refraction: low myopia (≤ −0.5 to 4 − 3.0 D), moderate myopia (≤ −3.0 to 4 − 6.0 D), and high myopia (≤ −6.0 D).…”

A study on prevalence of myopia and its associated factors in school children of Salem, Tamil Nadu

“…Prevalence of myopia was found to be 11.7%, showing a lower value than that of urban prevalence 13%. 6 In that girls were predominantly myopic when compared to boys, probably due to more time spent indoor, watching television, using mobiles, and habit of reading more books. According to International journal of health sciences survey among 4306 students, myopia was found in 4.74% of which 3.23% is contributed by girls.…”

“…Middle and Higher Secondary school was randomly selected and students of class 6 -12 were selected by Simple Random Sampling and students who were absent on the day of study and mentally challenged students were excluded from the study and the final study sample was of 854 students based on the previous prevalence of myopia 13% with absolute precision of 2.5%. 6 Students were explained about the study and after getting consent, a pilot study was carried out to standardize the study. Students were examined for refractive error by Snellen's chart and by non-cycloplegic auto refractometry and pinhole test.…”