Amblyopia, or lazy eye, causes poor vision in one or both eyes. Experts used to think that infancy or early childhood was the only time to treat it but that theory is changing.

Chris Williams was diagnosed with amblyopia a year ago but the 17-year-old's poor vision improved with recent treatment.

That's good news because kids Chris' age and older are often told their treatment window is closing.

Dr. Richard Hertle, with Children's Hospital of Pittsburgh says, "It was believed that the visual system stops responding to treatment usually about the end of the first decade."

Dr. Hertle says that may not be the case. He co-authored a nationwide study of seven to 17-year-olds with lazy eye.

"They were randomized into basically two treatment groups depending upon their age," he says.

The kids were treated with a variation of glasses and patching or drops in the good eye to force more use of the lazy eye.

Dr. Hertle says, "The younger children were randomized to glasses alone versus glasses plus what we called, kind of off-handedly, the kitchen sink of treatment which was everything else."

Many of the kids in the study did show vision improvement, including Chris.

If you've been told that your child is too old for treatment of lazy eye, Dr. Hertle says, "Take them back to the eye care professional and say, 'are there treatments now for my child that weren't there before?'"

None of the children in the study regained 20-20 vision. Researchers defined "improvement" as being able to read at least two more lines on a standard eye chart. The study was funded by the National Eye Institute.

Lazy Eye
Lazy eye (amblyopia) is a condition in which an otherwise healthy eye doesn't see as well as it should. As an infant grows, vision develops and matures through constant stimulation of the visual system. If something interferes with the ability of clear images to get into the eye, the visual system doesn't develop properly in that eye. Eventually, the brain learns to ignore the images coming through the affected eye, resulting in a loss of vision.

According to the American Academy of Ophthalmology, lazy eye affects about two percent of children in the U.S. The most common cause is strabismus, or misalignment of the two eyes (crossed eyes). Lazy eye may also be caused by differences in refractive error in the two eyes (i.e., one eye is more nearsighted or farsighted), cataracts (cloudiness of the lens of the eye), eye injury or droopy eyelids.

Treating Amblyopia
Amblyopia is usually detected during routine eye examinations in childhood. If there is an underlying cause for the problem (like a cataract, refractive error or strabismus), eye professionals will address the problem.

Even when underlying problems are corrected, amblyopia doesn't immediately disappear. The visual system in the weak eye must be stimulated to enable vision to develop. The most common way to treat the problem is through eye patching, in which a light-blocking eye patch is placed over the stronger eye. The patch is worn for several weeks to months. The process forces the brain to use images from the "weaker" eye - strengthening the visual system in that eye. Another way to strengthen the weaker eye is by placing atropine eye drops into the better eye. Atropine temporarily blurs the vision in the good eye and enables the visual system in the weaker eye to strengthen.

Expanding the Treatment Window
Eye patching and atropine drops have traditionally only been used for younger children with amblyopia. Previously, health experts believed a child's vision system was fully developed by nine, and unable to change. However, recent research suggests doctors may be able to intervene in older children as well.

The "Randomized Trial of Treatment of Amblyopia in Children Aged 7 to 17 Years" studied older children with amblyopia. The participants were divided into two groups. One group received prescription glasses. The second group (active treatment) received the glasses and an eye patch, or an eye patch plus atropine. Those in the active treatment group were instructed to perform near visual activities (like using a GameBoy, homework, reading, workbooks or computer work) for at least one hour a day.

The researchers found one-fourth of those who received the corrective glasses experienced improved visual acuity. For children 7 to 12, glasses plus patching or patching and atropine doubled the response rate. Patients 13 to 17 experienced improved visual acuity regardless of whether they were using eyeglasses or patching.

Despite the positive effects of amblyopia treatment in older children, doctors caution the treatment didn't bring the weaker eye up to 20/20 vision. The best time to intervene is still during early childhood. Routine eye screenings can detect the problem in young children and give doctors times to intervene early, increasing the chance of successful improvement of vision.

Sources
Richard Hertle, M.D., Pediatric Ophthalmologist, Children's Hospital of Pittsburgh, 3705 Fifth Ave., Pittsburgh, PA 15213.

Web Resources
For information about the study:
National Eye Institute

For information about amblyopia: