Researchers at Johns Hopkins and 54 eye-care centers across North America have found two competing methods of correcting a mild form of children's amblyopia--pejoratively called "lazy eye"--are equally effective in correcting the vision disorder.

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.

"Amblyopia is the most common cause of visual loss in children and young adults," says Michael X. Repka, the Johns Hopkins Children's Center and Wilmer Eye Institute ophthalmologist 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.

Researchers found visual acuity in the amblyopic eye improved for most of the children in each group, with 79 percent improvement in the patching group and 74 percent improvement in the atropine group. Most parents reported that their children tolerated treatment well, but parents of children in the atropine group were generally more satisfied with treatment than parents of children who wore eye patches.

"With atropine, you simply put the drop in once in the morning and there's no more monitoring of the child for the day," Repka says. "With the patch, children have to be continuously monitored since they often remove the patch. Despite the advantages of atropine, our data suggest ophthalmologists generally prescribe patching 97 percent of the time."

Amblyopia usually develops early in a child's life. Most ophthalmologists recommend treatment before a child turns 8, beyond which age treatment success rates appear to drop. The severity of amblyopia varies and is usually the result of strabismus (misaligned eyes) and/or a difference in each eye's refractive abilities.

More than 200 researchers at 55 centers in Mexico, the United States and Canada contributed to the study, which was funded by the National Eye Institute of the NIH. Precision Vision, Stereo Optical Company, Beiersdorf-Jobst Inc. and Bausch and Lomb Pharmaceuticals Inc. provided materials for the study.