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Older Children and Lazy Eye: Is It Too Late?

By Dr. Richard Liston

 New studies suggest that amblyopia treatment may be more successful in older children than previously thought.

There is no doubt that treatment of amblyopia is more effective when children with amblyopia are identified and treated at an early age (generally less than seven years of age). This fact provides the rationale for screening programs designed to detect children with amblyopia at an early age.

Unfortunately, things do not always go as planned. Screening programs, however effective, do not identify every child with amblyopia at an early age. Other children may be identified early but do not receive adequate treatment when they are young.

Why is early detection and treatment of amblyopia so important? To understand this, it is necessary to understand some important facts concerning visual development in children.

Most of us recognize that the ability to learn a language is much greater in children than in adults. Similarly, the developing nervous system of a child has a critical period of visual development. During this time, the development of good vision occurs and requires a clearly focused image on the retina (the sensory tissue lining the back of the eye). In addition, the brain must actually use both eyes, without overly favoring one eye and suppressing the other eye (which may then become amblyopic). If all goes well, good vision in both eyes will result as the child matures.

Unfortunately, misalignment of the eyes (strabismus), the need for strong spectacle correction, cataracts, and other conditions may interfere with this normal visual development and lead to amblyopia.

Although not all children mature at the same rate, the critical period of visual development has generally been thought to begin in early infancy and last until age eight to ten years. Traditional teachings and beliefs have been that treatment for amblyopia after the age of 10 years or so is not effective.

However, a recent study (the Amblyopia Treatment Study 3) by the Pediatric Eye Disease Investigator Group (PEDIG) (sponsored by the National Institutes of Health), has suggested that amblyopia treatment in older children may be more effective than previously thought.

Over 500 patients with amblyopia between ages seven and 18 were studied by PEDIG. Half of these children were treated with glasses alone and were designated the “control group”. The other half, designated the “treatment group,” wore glasses, patched the better-seeing eye for two to six hours daily (with at least one hour of near activities) and, further, used dilating drops in the better-seeing eye to blur the vision in the good eye.

The results from the PEDIG 3 study did not agree with traditional teachings: In younger patients, between seven and less than 13 years old, over 50 percent of the treated patients showed at least two lines of improvement in visual acuity in the amblyopic eye (compared to 25 percent in the control group who wore glasses alone). This included patients who had been treated for amblyopia in the past.

In older children (13 to 18 years of age), only those never previously treated for amblyopia showed a benefit from treatment. Specifically, 47 percent of those treated showed improvement (compared to 20 percent of those in the control group treated with glasses alone).

In the PEDIG 3 study, treatment lasted for four months or until no further improvement in visual acuity was observed. Unfortunately, most seven to 18 year old children in this study who responded to treatment were still left with some reduced vision in the amblyopic eye at the conclusion of the treatment.

At this point, it is not known if the improved vision persisted once treatment has ended. Further studies on this issue are being undertaken and the results will likely be available in a few years.

So what is the take home message? Treatment of amblyopia is possible later in childhood than previously thought. Children age seven to 12 may respond to treatment whether or not they have been treated in the past. Children 13 and older may also respond to treatment, but only if they have never been treated in the past. Please discuss these issues with your child’s eye doctor. He or she will help you make the right decision for your child with amblyopia.