Handheld Screening Device to Detect Amblyopia

Article: NIH-funded study shows screening device accurately detects amblyopia (lazy eye)
Source: National Eye Institute
Published: September 27, 2021

The PVS measures bilateral fixation via
retinal nerve fiber birefringence at the fovea

Colloquially called "lazy eye," amblyopia results when there is an underdeveloped connection between the eye and the brain, leading the brain to favor the vision in the better-seeing eye as those synapses strengthen and the synapses with the worse-seeing eye diminish. This can occur as a result of a variety of underlying causes, with anisometropia (or unequal refractive error) being the most common cause. Other factors leading to amblyopia include strabismus or tropia (an eye misalignment), visual deprivation, and high astigmatism. Where strabismus is the underlying etiology, detection of an eye misalignment in early childhood can prevent difficulties in academic performance. However, many pediatricians and primary care providers are not exposed to vision testing beyond basic visual acuity. Funded by the National Eye Institute, researchers are exploring a prototype handheld screening device to assess the eyes' ability to fixate together. The Pediatric Vision Scanner (PVS) simultaneously scans both retinas, specifically the fovea, with a polarized laser to detect even small-angle deviations. The device then provides a binocularity score, which is used to determine whether the child needs referral for more specialized assessment. The study recruited 300 children ages 2 to 6 with no known eye disorders. Two non-ophthalmic research associates were trained to use the device to screen each child, and the results were compared to eye examination performed by a pediatric ophthalmologist who was masked to the device's results. The device showed a 100% sensitivity, detecting all 6 cases of amblyopia and/or strabismus that agreed with the professional eye examination. However, the device also flagged an additional 45 children as possibly having amblyopia and/or strabismus who were later determined by the eye examination to be normal. The study did not compare this prototype with photo-screening devices which detect risk factors of amblyopia via differences in light reflexes between the two eyes. Despite a relatively low threshold of sensitivity (resulting in a high rate of false positives) in this prototype, the test requires only 2.5 seconds to perform, which could be a beneficial addition to busy pediatric practices.

My rating of this study: ⭐⭐

Shah SS, Jimenez JJ, Rozema EJ, et al. "Validation of the Pediatric Vision Scanner in a normal preschool population." J AAPOS.  25(4):216.e1-216.e4. 1 August 2021. https://doi.org/10.1016/j.jaapos.2021.03.010