Visual impairment and refractive error in school children in Bhutan

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Uncorrected refractive error is the leading cause of visual impairment; 48.9% globally and 62.9% in South Asia (Bhutan is part of this region) as estimated by the Vision Loss Expert Group (VLEG). Recent studies document a wide global variation in the prevalence of refractive error and predict that without control interventions the prevalence of myopia will significantly increase globally, affecting nearly 5 billion people by 2050. Considering its high prevalence and significant socioeconomic impact, refractive error has gained priority as a public health challenge, particularly in children.

Bhutan did not have any authentic evidence on prevalence of visual impairment due to uncorrected refractive error in the country. The WHO Global Action Plan 2014-2019 emphasized evidence generation for blindness and visual impairment and evidence-based planning and intervention. To do so, IAPB SEA, Primary eye care department of Ministry of Health , Royal Government of Bhutan carried out a nation-wide survey in school going children of Bhutan, based on WHO protocol on Refractive Error in School Children (RESC) in 2019. The survey work was supported by Lions Clubs International Foundation (LCIF) and Mission for Vision (MFV). Essilor provided free glasses for those who were in need of corrective spectacles. The survey sampling frame covered all school-going children of Bhutan (168,000) including Monastic body (Informal education).

The survey result shows that the prevalence of uncorrected, presenting, and best-corrected visual impairment (VA <6/12) in the better eye was 14.5%, 12.8%, and 0.34%, respectively. Refractive error was the principal cause (94.2%) of impaired vision and 88% of children who could achieve VA ³ 6/9 with best correction were without necessary spectacles. The prevalence of myopia (£ -0.5 D) was 6.64% and was associated with female gender (P = 0.004), urban schooling (P = 0.002), and greater parental education (P<0.001). The prevalence of hyperopia (³ +2.0 D) was 2.17% and was significantly associated with lower class-level (P = 0.033), and female gender (P = 0.025). The overall prevalence of astigmatism (³ 0.75 D) was 9.75%.

The detail report has been published in recent publication of Plos One.

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