Amblyopia Screening and Treatment
Better early detection and new treatments could improve visual outcomes. Howard Larkin reports.
Early screening has been shown to reduce amblyopia prevalence by 60% and residual amblyopia by 70% by the time children start school. Together with recent advances in theoretical understanding and new treatment options, emerging tools for detecting amblyopia and strabismus in preschool children may help further improve visual outcomes, Eileen Birch PhD said at the Association for Research in Vision and Ophthalmology 2021 Annual Meeting.
Only about one-quarter of children are successfully screened for amblyopia at age three, as recommended by the American Academy of Pediatrics, said Dr Birch, who is a Senior Research Scientist and Director of the Pediatric Vision Laboratory at the Retina Foundation of the Southwest, Dallas, Texas, USA. High false positive rates are the major barrier, resulting in higher costs, parental anxiety and lack of confidence in results, and reducing the likelihood of referrals for eye care.
NEW DEVICES AND TREATMENTS
A recently developed retinal birefringence scanning device could help, Dr Birch said. The device scans in a circle centred on the fovea at 100Hz. If fixation on the central fovea holds steady, this produces a reflected signal doubling of 200Hz due to the regular birefringent nature of the tissues surrounding the central fovea. If fixation does not remain steady or is off centre, due to amblyopia or some other ocular defect, there is little or no birefringence, so the reflected signal contains little or no 200Hz signal.
In a study involving 400 preschool children evaluating the device against blinded comprehensive eye examinations by a paediatric ophthalmologist, the device showed 97% sensitivity to detect amblyopia/strabismus, and 90% specificity to identify those with neither, Dr Birch said. (Jost et al. 2014, 2015) The device won FDA the PVS won FDA de novo clearance, with indications for screening young children for amblyopia and strabismus, as the blinq (Rebion) in 2016, she noted.
Dr Birch and colleagues are currently developing a device that measures visual acuity in preschool children with eye tracking. It features a stimulus on a screen that fades into the background if the child’s visual acuity is below age-normal. A camera records the child’s eye movement to detect when the shrinking dots are too small to be seen. The current device uses an iPad pro and clip on camera for maximum versatility.
“We are evaluating how accurate this approach is for screening preschool children,” she said.
Dr Birch also noted development of a device to monitor eye patch use that sticks to the inside of the patch to ensure accurate placement and comfort. Such monitoring may help improve adherence with patching and assessment of its effectiveness, which varies significantly.
Eileen Birch: firstname.lastname@example.org