February 15, 2022
By Aparna Gopalakrishnan, Jameel Rizwana Hussaindeen, Viswanathan Sivaraman, Meenakshi Swaminathan, Yee Ling Wong, James A. Armitage, Alex Gentle, Simon Backhouse
The Sankara Nethralaya Tamil Nadu Essilor Myopia (STEM) study assessed the distribution of refraction, ocular biometry, and the prevalence of myopia in a large group of schoolchildren in South India. A total of 14,342 children, aged 5 to 16 years, underwent refraction assessment and a sub-cohort of 7,901 children underwent ocular biometry measurements. Myopia was defined as a spherical equivalent (SE) refraction of ≤-0.75D, and high myopia was defined as SE ≤-6.00D using the non-cycloplegic threshold previously proposed by the STEM group using the same cohort.
The prevalence of myopia was found to be 17.5%, out of which 3% had high myopia. Axial length (AL) was significantly longer with older age (mean difference [MD] of 1.03mm between those aged 5-10 years and those aged 13-16 years; p<0.001), in boys compared to girls (MD of 0.49mm; p<0.001), and in myopes compared to non-myopes (MD of 1.05mm; p<0.001). Older age (odds ratio [OR] of 2.61; 95% confidence interval [CI], 1.40 to 4.88) and urban school location (OR of 2.53; 95% CI, 1.13 to 5.68) was associated with increased odds of presence of myopia in schoolchildren in India.
This is one of the first studies to have measured refraction and ocular biometry in a large cohort of children in India, and the study confirmed that biometry patterns in Indian children were similar to findings observed in other ethnicities. The myopia prevalence found in the current study was nearly four-fold, compared to previous observations reported in South India from 20 years ago. These findings indicate the need to prioritize community and school-based screening for myopia among children at risk, combat the increasing myopia burden, and mitigate sight-threatening complications due to myopia progression and high myopia.
Background: The Sankara Nethralaya Tamil Nadu Essilor Myopia (STEM) study is a longitudinal study aiming to assess prevalence, incidence, and risk factors associated with myopia onset and progression among schoolchildren in Tamil Nadu, South India. The present study reports the methodology, myopia prevalence, distribution of refraction, and ocular biometry.
Methods: Eleven schools from two districts were included in the study. As part of the screening, all the children who provided consent had their visual acuity assessed and refractions measured using open-field autorefraction. A subset of emmetropic children in grades 1, 4, and 6 and all children with identified refractive error had ocular biometry measurements taken using a non-contact biometer. Binocular vision assessment, including measurement of amplitudes of accommodation, convergence amplitudes, accommodative response, and phoria status, was performed. Parents of all children were provided with a modified version of the Sydney Myopia Study questionnaire for risk factor assessment.
Results: A total of 14,342 children were included in the baseline study. The age range of the children was between 5 and 16 years (mean age of 10.2 [SD 2.8] years). The overall prevalence of myopia (defined as spherical equivalent refraction of ≤-0.75 D) in the study population was 17.5% (95% CI, 14.7% to 20.5%). There was an increase in the prevalence of myopia with older age (p<0.001). There was no difference in the prevalence of myopia between boys and girls (14.8% versus 15.5%; p=0.24). The prevalence of myopia among children studying in urban school locations was higher than children whose schools were located in suburban locations (16.4% versus 12.5%; p<0.001). High myopia (defined as SE of ≤-6.00 D) was present among 3% (95% CI, 2.7% to 4.2%) of myopic children. Ocular biometry measurements were available for 7,901 children. The mean axial length and anterior chamber depth increased with older age (p<0.001), whereas corneal curvatures decreased with age. The odds of myopia increased with older age (OR of 2.61; 95% CI, 1.40 to 4.88; p=0.003] for children aged 13 to 16 years compared to those aged 5 to 10 years) and urban school location (OR of 2.53; 95% CI, 1.13 to 5.68; p=0.02] compared to suburban locations) after adjustments for gender and axial length.
Conclusion: Myopia prevalence in South India has increased significantly from that reported in the past, which suggests that myopia is becoming a public health problem in the country.
Aparna Gopalakrishnan is with the Myopia Clinic, Sankara Nethralaya, Unit of Medical Research Foundation, Chennai, India, and the School of Medicine, Faculty of Health, Deakin University, Geelong, Victoria, Australia; Jameel Rizwana Hussaindeen, Viswanathan Sivaraman, and Meenakshi Swaminathan are with the Myopia Clinic, Sankara Nethralaya, Unit of Medical Research Foundation, Chennai, India; James A. Armitage, Alex Gentle, and Simon Backhouse are with School of Medicine, Faculty of Health, Deakin University, Geelong, Victoria, Australia; and Yee Ling Wong is with R&D AMERA, Essilor International, Singapore, Singapore.
This article is sponsored by Essilor.
- Gopalakrishnan, A., Hussaindeen, J.R., Sivaraman, V., Swaminathan, M., Wong, Y.L., Armitage, J.A., Gentle, A. and Backhouse, S., 2022. Prevalence of myopia among urban and suburban school children in Tamil Nadu, South India: findings from the Sankara Nethralaya Tamil Nadu Essilor Myopia (STEM) Study. Ophthalmic and Physiological Optics. doi:10.1111/opo.12943
- Gopalakrishnan A, Hussaindeen JR, Sivaraman V, Swaminathan M, Wong YL, Armitage JA, Gentle A, Backhouse S. The Sankara Nethralaya Tamil Nadu Essilor Myopia (STEM) Study—Defining a Threshold for Non-Cycloplegic Myopia Prevalence in Children. Journal of Clinical Medicine. 2021; 10(6):1215. https://doi.org/10.3390/jcm10061215