Commentary: Should we restrict vision screening in primary school children?

Sir,

Childhood blindness is a major global public health problem, and of the 19 million blind children, 12 million is caused by uncorrected refractive error.[1] One of the most common strategies to identify children with refractive error is the screening of children in school. Since 1994, school screening is an integral part of the National Program for Control of Blindness (NPCB). However, initially the focus was on children from 5th to 10th standard.

In this study,[2] the authors looked at the yield of screening done on children in class 3rd to 5th in 23 government schools of New Delhi. Though teachers performed the screening, to avoid excess false positives, the visual acuity cut off was increased to 6/12 (from 6/9 in NPCB) and those identified having any visual problem, underwent cycloplegic refraction. Overall, the prevalence of myopia was 2.5%, hyperopia was 0.6%, and astigmatism was 1.3%. Though the sensitivity of screening was quite high (92.3%), the specificity was moderate (72.6%). Apart from this, the compliance was 36% at 6 months. Further, there were 56 children referred for higher treatment. Hence the author's feel that, since the yield is not optimum, they recommend an annual screening to be conducted primarily in secondary school, and based on the availability of resources, conduct screening in primary school in the government setting.

However, we feel that, based on one study in primary school, the screening should not be restricted at the primary school, as this primary school is not a representative sample for the entire country's primary school population. Apart from this, there were also 56 children identified with other problems. Had the screening not been done, these children would have been deprived of care and some of them could have become permanently visually impaired. If there is a limitation of resources or personnel, we need to find a different strategy for screening this group of children or different ways to find personnel or resources.

It is well known that the prevalence of hyperopia is higher in younger children and ranges from 8.4% at the age of 6 years to 2–3% at the ages of 9–14 years and approximately 1% at age of 15 years.[3] Refractive Error Study in Children (RECS) in India also showed the prevalence of hyperopia to be 7.4% in New Delhi (15.6% at the age of 5 years to 3.9% at the age of 15 years)[4] to 0.7% in Mahabubnagar (0.7% at 7 years to 1.1% at 15 years).[5] Similarly, a study from Hyderabad showed prevalence of hyperopia to be 3.3% in urban area to 3.1% in rural area (4.6% at 7 years to 0.4% at 15 years).[6] Apart from this, the global prevalence of myopia in South Asia ranges from 5.3% at age of 5 years to 13% at age of 15 years.[7] There are also projections that this is going to increase in future. Hence, restricting the screening to a given set of children should be refrained from. Rather, a strategy to screen all children from newborn to high school should be thought of to achieve our goal for eliminating avoidable blindness in children.