A small, open-label clinical trial in the United States is raising hope for restoring at least some lost vision in older children, and even adults, with amblyopia.
If amblyopia is caught early enough, putting a patch over the dominant eye teaches the brain to pay attention to the weaker eye, strengthening its vision. Unfortunately, this strategy works best until about age five or six. After that, the ‘critical period’ when the brain can rewire its visual circuits begins to close, and vision loss is hard to reverse.
After 12 weeks of treatment, participants could read, on average, 1.2 more lines in an eye chart than when they started”
Boston Children’s Hospital has been trialling the use of the drug donepezil (Aricept), a medication used for Alzheimer’s disease.
While improvements in vision were modest and not universal, they were stable and could pave the way to larger, placebo-controlled trials, potentially trying different drugs and concurrent visual stimulation.
The trial results were published recently in Scientific Reports,1 with study authors saying it was a “bench-to-bedside proof of concept that brain plasticity can be rekindled”.
“We hope it will inspire a larger-scale, placebo-controlled trial,” said neuroscientist Dr Takao Hensch.
The trial enrolled 16 participants averaging 16 years of age, ranging from nine to 37. All had been treated with eye patching in the past and had stopped treatment due to no further improvement in vision.
Before receiving donepezil, children under 18 patched their weak eye for four weeks, at least two hours daily. Adults were spared this requirement.
After this run-in period, the children took 2.5mg of donepezil daily while continuing to patch, while adults took 5mg. If, at four weeks, vision hadn’t improved by at least one line (or five letters) on the eye chart, the dose was increased. Doses were capped at 7.5mg for children and 10mg for adults.
After 12 weeks of treatment, participants could read, on average, 1.2 more lines in an eye chart than when they started. While some did not respond, four of the 16 had improvements of two lines or greater.
“The good news is that there were gains in visual acuity for some patients, none had significant side effects, and the improvements were maintained even after stopping treatment,” said Boston Children’s ophthalmologist, Dr Carolyn Wu.
Reference
1. Wu, C., Gaier, E.D., Nihalani, B.R., et al., Durable recovery from amblyopia with donepezil. Sci Rep 13, 10161 (2023). DOI:10.1038/s41598-023-34891-5.
