To assess the accuracy of a popular photoscreening device in a pediatric population at high risk for strabismus and refractive errors, these authors prospectively studied 100 children ages 4 months to 12 years recruited from a Miami, Florida university pediatric ophthalmology clinic, a developmental disorders clinic, and a day care center. The device, an off-axis instant film Medical Technology Inc. (MTI) Photoscreener which is marketed to pediatricians, produces a photographic image of a flash of light reflected by the cornea and also a red reflex refracted by the eye and reflected back from the fundus through the pupil. The authors compared the photoscreening device results with those of a complete ophthalmologic evaluation performed by one of 3 pediatric ophthalmologists. Children with significant known eye disorders including amblyopia, cataract, glaucoma or a history of prematurity were excluded. The sensitivity and specificity of the MTI Photoscreener in detecting refractive error, strabismus and other ocular abnormalities known to be causally associated with amblyopia were assessed and compared to ophthalmologic evaluation which was the “gold standard.”
The mean overall sensitivity of the MTI Photoscreener in detecting any amblyogenic factor was 86% (range 80–91%) and its mean specificity was 52% (range 20–67%). The sensitivity and specificity of the photoscreener identification for strabismus, various refractive errors and other amblyogenic factors varied widely among the different evaluators using photos produced by the device.
These results suggest caution in relying on photoscreening to detect strabismus and refractive errors in children.
The American Academy of Pediatrics,1 many other organizations, state governments and schools have mandated vision screening at various ages to ensure timely discovery of treatable refractive errors. This is particularly vital for amblyopia, for which early treatment is most efficacious and attainment of visual maturity (usually around age 8) precludes treatment. Intensive marketing of photoscreening devices has been directed at pediatricians for several years. This study, undertaken under conditions that were probably more controlled than those afforded by a routine pediatric office setting, indicates that these devices may not be sufficiently reliable at present to replace the traditional methods of vision screening recommended by the AAP.
As these authors note, the lack of a well-accepted standard for abnormal screening results makes comparison with other photoscreening systems difficult. Nonetheless, other studies have reported comparable sensitivity and specificity ranging from 62–94%.2–,4 If used in large programs, a low specificity will result in potentially costly over-referral of normal patients. We cannot yet see a place for photoscreeners in most pediatric practices.