Researchers make strides in amblyopia
Accumulating evidence suggests that multiple treatments can help people with amblyopia, according to a review of the literature.
Research over the past 20 years has provided “reliable scientific evidence to show that prescribing refractive correction and atropine or occlusion with additional interventional material should optimise visual outcomes in amblyopic patients with minimal side effects,” wrote Gail DE Maconachie and Irene Gottlob of the Ulverscroft Eye Unit at the University of Leicester, UK. They published their findings in Biomedical Journal.
In amblyopia, one eye doesn’t function as well as the other. This mostly occurs because something forces the visual system to prefer one eye. The most common reason is a difference in refractive error between the two eyes.
A difference in spherical correction (anisometropic amblyopia) and strabismus are the two most frequent underlying causes. But other problems such as unilateral cataract or ptosis can also bring about amblyopia.
As far back as the 1st century AD, physicians have treated amblyopia by covering the dominant eye, forcing the visual system to develop capacities in the affected eye, a treatment known as occlusion therapy. It has often been used to treat children on the theory that the condition will become more difficult as the visual system matures.
But a path-breaking review by Snowdon and colleagues found that few trials had rigorously tested this treatment or any other. Also, few studies have explored the hypothesis that amblyopia can only be treated before the nervous system matures.
Since then, many randomised controlled trials have been done, and Monachie and Gottlop set about distilling their conclusions.
They found evidence that occlusion therapy works, but children naturally resist wearing eye patches. Therefore, some studies have examined just how much occlusion is necessary. The results indicated that 2 hours per day of occlusion worked as well as 6 hours per day for moderate amblyopia. Likewise, 2 hours per day worked as well as 6 hours per day for severe amblyopia.