Clinical evaluation of a commercial photorefractor

The Visiscreen 100 is a system designed to detect ocular anomalies photographically. Photorefractions obtained in 63 consecutive 3-month-old to 8-year-old patients were compared in a masked fashion with results obtained by conventional techniques, including cycloplegic refraction. In 87% of the 57 patients with analyzable photographs, photorefractive and examination results correlated for the detection of constant tropias. The photorefractor detected all ocular media opacities. In 77% of the cases, its refraction was within 2.5 diopters or 33% of the cycloplegic spherical equivalent. In detecting abnormal ocular status, the Visiscreen had a 91% sensitivity and a 74% specificity. The overall agreement rate in distinguishing abnormal from normal status was 84%. Most errors were related to inaccuracies in fixation and positioning, rather than the optical principles utilized. This device offers a rapid technique for the detection of factors predisposing preverbal children to amblyopia.