Screening for childhood blindness and visual impairment in a secondary school in rural Malawi

Sir,

Childhood blindness is one of five areas of disease control in Vision2020: The Right to Sight,¹ and it is estimated that there are 300 000 blind children in Africa.² However, data on the epidemiology of childhood blindness in sub-Saharan Africa is scant, as children are rarely included in blindness surveys. Historically, information has been obtained from schools for the blind and, more recently, the key informant method,³ but this does not address children with milder forms of visual impairment. Screening for visual impairment in regular schools may also yield useful information, although children with debilitating visual impairment may be less likely to attend, and secondary school attendance is not universal in Africa.

We examined 1000 children (aged 11–19 years) attending secondary school in Malamulo in rural Malawi. Presenting visual acuity (VA, with spectacles if owned, but uncorrected otherwise) was assessed with Snellen Chart at 6 metres. If presenting VA was <6/18 (‘visual impairment’), they were invited to attend Malamulo Hospital Eye Department for formal refraction and slit-lamp examination, following suitable permission. Spectacles were dispensed if necessary.

There were 39 students (3.9%) with presenting VA<6/18 in one (N=20) or both (N=19) eyes. Among them 20 (51.2%) were male. One student (0.1%) was blind (VA<3/60) bilaterally, due to high myopia (−16.0 dioptres), and one had unilateral blindness from amblyopia (due to strabismus). Causes of visual impairment are presented (Table 1). In all, 29 (14 in bilateral group and 15 in unilateral group) attended the full examination. Of the 16 people with refractive error, only 4 had spectacles (25% spectacle correction coverage).

Table 1 Aetiology of visual impairment in a secondary school in rural Malawi

Our finding that uncorrected refractive error (URE) is the main form of visual impairment is consistent with the major cause of visual impairment globally in children aged 5–15 years.⁴ Early correction of refractive error is crucial, as it may lead to reduced education and employment activities and harm quality of life. School eye-health programmes are useful for screening for refractive error in Africa. Cost of spectacles is a major barrier to spectacle use, and students are more likely to wear spectacles if they have myopia and if the spectacles are free.⁵ In Africa, where the spectacle correction coverage is low, adequate supply of cost-effective spectacles is required to reduce the burden of URE.