Portland, Ore.

A national clinical trial shows older children can benefit from treatment for amblyopia. Prior to this study, many eye care professionals thought the ability to treat amblyopia, commonly known as lazy eye, drastically declined after age 7.

The study, published in the April issue of Archives of Ophthalmology, was conducted at 49 clinical sites nationwide, including Oregon Health & Science University Casey Eye Institute.

"This is the first high-quality clinical study to show that older children may still be able to respond to treatment," said David Wheeler, M.D., principal investigator of the study at Casey Eye Institute and an associate professor of ophthalmology and pediatrics in the OHSU School of Medicine. "While we have known for decades that younger children respond to treatment for amblyopia, this study shows us that older children should be treated for the disorder as well."

Amblyopia is one of the most common childhood eye disorders, affecting approximately 3 percent of all children in the United States, and is a leading cause of visual impairment in children, and young and middle-aged adults. Amblyopia occurs when a child's otherwise healthy eye does not develop normal sight because the brain has favored the other eye. If the brain receives abnormal or unequal vision input, it will favor one eye over the other, limiting the development in the portion of the brain responsible for the weaker eye. A large difference in refractive error between the two eyes can lead to amblyopia, as can eye misalignment such as a crossed or wandering eye.

Children aged 7 to 18 were enrolled in the study and divided randomly into two groups. One group was given new prescription glasses. The other group was given new prescription glasses and underwent active treatment for amblyopia. Active treatment included an eye patch worn over the unaffected eye for two to six hours daily, atropine drops in the unaffected eye each day for children younger than 13, and near-vision activities, including computer games, while wearing the patch. The treatment is designed to encourage the child to use the eye with amblyopia.

Investigators defined vision improvement as the ability to read at least two additional lines on a standard eye chart using the eye with amblyopia. The study found that 53 percent of children aged 7 to 12 who received active treatment improved, while only 25 percent of children in the same age group who received only glasses improved. For children aged 13 to 17 who received active treatment, only 25 percent improved, while 23 percent who received only glasses improved.

However, the study also found that 47 percent of children aged 13 to 17 who received active treatment and had not previously been treated for amblyopia improved, while only 20 percent of children in this same group who received only glasses improved.

"Parents and primary care providers need to know that amblyopia can usually be treated," said Wheeler. "Treatment recommendations are always being revised, so don't assume it is too late to see a physician and get an eye exam."

The study was funded by the National Eye Institute, part of the National Institutes of Health.