Clinical evaluation of a commercial photorefractor
K. S. Morgan and W. D. Johnson
LSU Eye Center, Department of Ophthalmology, New Orleans 70112.
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.
