A handheld vision screening device to test for amblyopia and strabismus has been found to have a sensitivity of 100%, a specificity of 85%, and a median acquisition time of 28 seconds, according to a study published in the Journal of American Association for Pediatric Ophthalmology and Strabismus.
The prospective study involved 300 children recruited from two Kaiser Permanente Southern California pediatric clinics. The patients, aged 24-72 months, were first screened by trained research staff for amblyopia and strabismus using the device, called the Pediatric Vision Scanner (PVS). They were subsequently screened by a pediatric ophthalmologist who was masked to the previous screening results and who then performed a comprehensive eye examination.
With the gold-standard ophthalmologist examination, six children (2%) were identified as having amblyopia and/or strabismus. Using the PVS, all six children with amblyopia and/or strabismus were identified, yielding 100% sensitivity. PVS findings were normal for 45 children (15%), yielding a specificity rate of 85%. The positive predictive value was 26.0% (95% confidence interval, 12.4%-32.4%), and the negative predictive value was 100% (95% CI, 97.1%-100%).
The findings suggest that the device could be used to screen for amblyopia, according to Shaival S. Shah, MD, the study’s first author, who is a pediatric ophthalmologist and regional section lead of pediatric ophthalmology, Southern California Permanente Medical Group.
“A strength of this device is that it is user friendly and easy to use and very quick, which is essential when working with young children,” said Dr. Shah in an interview. He noted that the device could be used for children as young as 2 years.
Dr. Shah pointed out that the children were recruited from a pediatrician’s office and reflect more of a “real-world setting” than had they been recruited from a pediatric ophthalmology clinic.
Dr. Shah added that, with a negative predictive value of 100%, the device is highly reliable at informing the clinician that amblyopia is not present. “It did have a positive predictive value of 26%, which needs to be considered when deciding one’s vision screening strategy,” he said.
A limitation of the study is that there was no head-to-head comparison with another screening device, noted Dr. Shah. “While it may have been more useful to include another vision screening device to have a head-to-head comparison, we did not do this to limit complexity and cost.”
Michael J. Wan, MD, FRCSC, pediatric ophthalmologist, Sick Kids Hospital, Toronto, and assistant professor at the University of Toronto, told this news organization that the device has multiple strengths, including quick acquisition time and excellent detection rate of amblyopia and strabismus in children as young as 2 years.
“It is highly reliable at informing the clinician that amblyopia is not present,” said Dr. Wan, who was not involved in the study. “The PVS uses an elegant mechanism to test for amblyopia directly (as opposed to other screening devices, which only detect risk factors). This study demonstrates the impressive diagnostic accuracy of this approach. With a study population of 300 children, the PVS had a sensitivity of 100% and specificity of 85% (over 90% in cooperative children). This means that the PVS would detect essentially all cases of amblyopia and strabismus while minimizing the number of unnecessary referrals and examinations.”
He added that, although the study included children as young as 2 years, only 2.5% of the children were unable to complete the PVS test. “Detecting amblyopia in children at an age when treatment is still effective has been a longstanding goal in pediatric ophthalmology,” said Dr. Wan, who described the technology as user friendly. “Based on this study, the search for an accurate and practical pediatric vision screening device appears to be over.”
Dr. Wan said it would be useful to replicate this study with a different population to confirm the findings.
Dr. Shah and Dr. Wan disclosed no relevant financial relationships.
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