Visual Acuity Screening in North Indian Schools: Testing Accuracy and Cost of Alternate Screening Models

Our study compares the sensitivity, specificity and cost of visual acuity screening as performed by all class teachers (ACTs), selected teachers (STs) and vision technicians (VTs) in north Indian schools.

Prospective cluster randomized control studies are conducted in schools in a rural block and an urban-slum of north India. Consenting schools, with a minimum of 800 students aged 6 to 17 years, within a defined study region in both locations, were randomised into three arms: ACTs, STs or VTs. Teachers were trained to test visual acuity. Reduced vision was defined as unable to read equivalent of 20/30. Optometrists, who were masked to results of initial screening, examined all children. Costs were measured for all three arms.

The number of students screened were 3410 in 9 ACT schools, 2999 in 9 ST schools and 3071 in 11 VT schools. Vision deficit was found in 214 (6.3%), 349 (11.6%) and 207 (6.7%), (p < .001) children in the ACT, ST and VT arms, respectively. The positive predictive value of VT screening for vision deficit (81.2%) was significantly higher than that of ACTs (42.5%) and STs (30.1%), (p < .001). VTs had significantly higher sensitivity of 93.3% and specificity of 98.7%, compared to ACTs (36.0% and 96.1%) and STs (44.3% and 91.2%). The cost of screening children with actual visual deficit by ACTs, STs and VTs, was found to be $9.35, $5.79 and $2.82 per child, respectively.

Greater accuracy and lower cost favours school visual acuity screening by visual technicians in this setting, when they are available.