A new NIH study has validated the accuracy of a handheld screening device in identifying children with amblyopia, also commonly referred to as lazy eye. The findings of the study are published in the Journal of the American Association for Pediatric Ophthalmology and Strabismus.^1,2

The effectiveness of the Pediatric Vision Scanner (PVS) in screening for amblyopia and strabismus was tested in a prospective study of 300 children, aged 2-6 years, who had no known eye conditions for amblyopia and strabismus. The screening was done by two non-ophthalmic research associates, who were trained to use the device. A comprehensive eye examination was done by a pediatric ophthalmologist, who was blinded to the results of the initial screening.

The screening device  is held at a distance of 14 inches from the eyes. The child is asked to fix his/her gaze on a smiley face, while the device is scanning both the retinas at the same time. A polarized laser probes nerve fibers in the fovea (light-sensitive part of the retina). Even a slight misalignment in this area can impair the ability of the brain to integrate images from both eyes. “The device calculates a binocularity score that indicates whether the child requires referral to an eye health physician for further investigation.”²

Six children (2%) were found to have amblyopia and/or strabismus, all of whom were detected with the help of the PVS and later on confirmed on eye examination, thus showing a sensitivity of 100% (95% CI, 54%-100%). Forty-five (15%) children suspected to have amblyopia were also identified on initial screening, but they were afterward found to have a normal eye examination showing a specificity of 85% (95% CI, 80%-89%).

Amblyopia develops when strabismus or misalignment of the eyes or decreased acuity in one eye prevents the brain from processing visual information from both eyes. The result is that the child then favors use of one eye, with the other eye becoming “lazy” due to non-use. Loss of vision in the affected eye cannot be corrected with either glasses or contact lens. The outcomes are poor school performance and impaired fine motor skills. Timely diagnosis therefore can prevent the loss of vision due to amblyopia. This is where the PVS comes in handy as a useful aid for early detection of children with the lazy eye. And, timely intervention can prevent the associated loss of vision. This screening can be done even at the level of the primary healthcare provider thereby reducing the number of referrals for specialist ophthalmic examination since this device detects amblyopia and not the risk factors for the condition. According to the study authors, with a cooperative child, time required for screening with PVS is as little as 28 seconds making it a feasible option for busy pediatricians and family physicians.

References

1. Shah SS, et al. Validation of the pediatric vision scanner in a normal preschool population. J AAPOS. 2021 Aug;25(4):216.e1-216.e4. doi: 10.1016/j.jaapos.2021.03.010.
2. National Institutes of Health News, September 27, 2021.