Comparison of preschool vision screening methods in a population with a high prevalence of astigmatism

PURPOSE. To compare the effectiveness of four methods of screening 3- to 5- year-old children for astigmatism high enough to require spectacle correcti on. METHODS. Lea Symbols Visual Acuity Screening (LSVAS), MTI Photoscreening (M TIPS), Nidek KM-500 Keratometry Screening (KERS), and Retinomax K-Plus Nonc ycloplegic Autorefraction Screening (NCARS) were attempted on 379 Preschool children who are members of a Native American tribe having a high prevalen ce of astigmatism that is primarily corneal in origin. The need for spectac le correction was determined by cycloplegic refraction. Receiver Operating Characteristic (ROC) curves were st, confidence intervals were determined, and area under the curves was compared. RESULTS. Astigmatism greater than or equal to 1.00 D was present in the rig ht eye of 47.5% and in the left eye of 48.0% of children. Spectacles were p rescribed for children < 48 months of age who had cylinder <greater than or equal to> 2.00 D and children < 48 months who had cylinder <greater than o r equal to> 1.50 D, with the result that 33% of subjects required spectacle s. Area under the ROC curve was 0.98 for NCARS, 0.92 for KERS, 0.78 for MTI PS, and 0.70 for LSVAS, and each of these values differed significantly fro m the other three (all P < 0.007). Testability was significantly higher for NCARS (99.5%) and KERS (99.7%) than for MTIPS (93.5%) and LSVAS (92.0%). CONCLUSIONS. In a population that included many children with astigmatism, objective, fully automated screening methods (NCARS and KERS) were superior to both visual acuity screening and photoscreening with subjective interpr etation in identifying children who had astigmatism requiring spectacle cor rection.