But the researchers also found parents generally preferred atropine treatment, in which the child receives painless eye drops that blur the unaffected eye, to patching, in which the child's unaffected eye is covered with a patch. Both treatments challenge the amblyopic eye to work harder at focusing properly by covering or blurring vision in the normal eye.
"Amblyopia is the most common cause of visual loss in children and young adults," says Johns Hopkins Children's Center and Wilmer Eye Institute ophthalmologist Michael X. Repka, M.D., who led the project. "If there is a good treatment with which the patients will comply, more cases of permanent visual loss can be prevented."
The study, published in this month's Archives of Ophthalmology, is the first systematic comparison of two methods for correcting amblyopia, and addresses doctors' questions about which method is better. Patching is prescribed much more often.
Researchers from Mexico, the United States and Canada randomized 419 children ages 6 years or younger, diagnosed with "moderate" amblyopia (visual acuity between 20/40 and 20/100 in the affected eye), into atropine and patching treatment groups. All children in the study had 20/40 vision or better in the unaffected eye. Each of the 204 children in the atropine group received atropine sulfate drops. The 215 children in the patching group were asked to wear an eye patch over the unaffected eye for an appropriate number of hours each day. Improvements in each child's amblyopia were assessed by comparing each child's visual acuity at the time of enrollment to his or her visual acuity after five, 16, and 26 weeks of treatment.