Amblyopia Treatment Study —Patching or Atropine Drops?

Amblyopia (am-blee-OH-pee-uh), or more commonly known as “lazy eye,” affects an estimated two or three of every 100 children in the United States. The disorder affects normal visual development because the brain has learned to favor one eye over the other.

Amblyopia can include an imbalance in the positioning of the eyes, such as strabismus, in which the eyes are crossed inward (esotropia) or turned outward (exotropia). The disorder can also be caused by a major difference in the refraction between the two eyes, such as nearsightedness (the inability to see things far away), farsightedness (the inability to see things close up) or astigmatism (which can result in blurred vision), or a combination.

Occlusion therapy (patching) the unaffected eye has been the standard treatment for amblyopia, despite the lack of meaningful data demonstrating its superiority over other treatments. An alternative treatment — drug therapy with cycloplegic eye drops (atropine) — has been known for almost a century. The method has been widely used when patching does not work.

However, atropine eye drops have seen little use as a primary treatment as shown by a 1997 survey by the Pediatric Eye Disease Investigator Group (PEDIG). It was found that 3 percent of eye care professionals prescribed atropine eye drops, while 97 percent preferred patching. A definitive study to compare the outcomes from both treatments was justified to determine if new practice guidelines for treatment were needed. Thus the most recent study — Amblyopia Treatment Study, which took place between April 1999 and April 2001. The study included 419 patients with the average age being 5.2 years. Forty-seven percent were female and 83 percent were white. Enrollment was restricted to children who had either not been previously treated for the condition or who had received no more than two months of treatment in the prior two years.

When patching the unaffected eye, the vision is stimulated in the affected eye, which helps the part of the brain that manages vision to develop more completely.

Atropine eye drops essentially do the same thing: by temporarily blurring vision in the unaffected eye, thereby forcing the eye with amblyopia to be used.

Because of social and psychological stigmas, children can and do remove the patch when their parents are not watching. With the eye drops there is no need for additional supervision.

Researchers found after six months that 79 percent of the 215 children who wore the eye patch at least six hours a day were treated successfully and 74 percent of the 204 children receiving the atropine drops once a day were treated successfully, making the difference clinically insignificant. In a quarter of the children, special glasses needed to be worn.

Side effects in varying degrees were found in both groups. In the patching group, mild skin irritation was reported at least once in 41 percent of patients, with moderate or severe skin irritation at least once in six percent of patients. In the atropine group, light sensitivity was reported for 18 percent of patients, eye lid or corneal irritation for four percent, and eye pain or headache for two percent.

Until now, “there has not been a good, well-documented study to show that atropine had the same effect as patching,” stated Dr. Stuart R. Dankner, a spokesman for the American Academy of Ophthalmology (AA0) and a pediatric ophthalmologist in Baltimore. “A majority of ophthalmologists were reluctant to use atropine because it’s potentially a longer-time therapy just like patching; and, if that amount of time is going to be invested, you want to know you’re going to get a good result in terms of improving vision in the weaker eye.”

Further followup of the participants in the original study will be ongoing until April of 2003 to see if there are any long-term advantages to either treatment method.

The Amblyopia Treatment Study was conducted by the PEDIG at 47 clinical sites throughout North America. The study was funded by the National Eye Institute (NEI), National Institutes of Health and coordinated by the Jaeb Center for Health Research in Tampa, Fla. and the Wilmer Eye Institute of Johns Hopkins University in Baltimore (Sources: NIH News Release, Mar. 13, 2002; HealthScoutNews, Amanda Gardner, Reporter, Mar. 13, 2002; Archives of Ophthalmology, March 2002. Pictures courtesy of the National Eye Institute, National Institutes of Health.

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