Polaroid photoscreening for amblyogenic factors. An improved methodology

The authors describe a new photoscreening camera designed to detect amblyogenic factors, including strabismus, asymmetric and abnormal refractive errors, and media opacities. The photoscreener uses eccentric photorefraction principles and provides two meridian photographs of the retinal reflex.

Pass/fail screening data from the photographs of 202 nondilated children as determined by two masked observers were compared with data from complete ophthalmologic examinations.

The photoscreener had a sensitivity rate of 87%, a specificity rate of 89%, a positive predictive value of 93%, a negative predictive value of 80%, and an overall agreement rate of 88%. The prescreening probability for amblyogenic factors was 63%. Constant strabismus was detected in all cases. Five intermittent strabismus cases were missed. Two patients with myopia, three patients with hyperopia, and five patients with astigmatism were missed. All media opacities were detected.

This new two-flash photoscreening camera, which uses high-speed Polaroid film, is an accurate, reliable method of detecting amblyogenic factors in undilated children. The camera offers promise as a useful mass screening tool.