Last modified: Monday, November 1, 2004
Research points to easier treatment for amblyopia, or "lazy eye"
BLOOMINGTON, Ind. -- A study conducted by the Pediatric Eye Disease Investigator Group has found that children with moderate amblyopia, often called "lazy eye," benefit as much from receiving atropine eye drops only twice a week as they do with the standard treatment of receiving daily atropine drops.
This finding should lead to better compliance with treatment, less expensive treatment and improved quality of life for children with amblyopia, the most common cause of visual impairment in childhood.
The results of the study appear in the November issue of the journal Ophthalmology. The study was funded by the National Eye Institute of the National Institutes of Health and coordinated by the Jaeb Center for Health Research in Tampa, Fla.
"The easier we can make the treatment of amblyopia for the parents and kids, the more likely they will be to follow the doctor's instructions. One reason treatment of amblyopia can fail is due to poor compliance from the kids and/or their parents," said Dr. Don Lyon, chief of pediatrics/binocular vision at the Indiana University School of Optometry, which participated in the PEDIG study. "If we can diagnose children with amblyopia early and offer them treatment options which are easy and effective, we can have a positive effect and keep them from having a permanent vision impairment."
Amblyopia, which usually begins in infancy or childhood, is a condition of poor vision in an otherwise healthy eye. The condition exists because the brain has learned to favor the other eye. Although the eye with amblyopia looks normal, there is interference with its normal visual processing that limits the development of a portion of the brain responsible for vision. The most common causes of amblyopia are crossed or wandering eyes or significant differences in refractive error -- such as farsightedness or nearsightedness -- between the two eyes. Amblyopia is the most common cause of monocular (one eye) visual impairment among children and young and middle-aged adults.
Standard treatment has involved a daily drop of atropine in the unaffected eye, causing blurred vision in that eye, or the daily patching of the unaffected eye. Both approaches strive to stimulate vision improvement in the weaker eye by helping the part of the brain that manages vision to develop more completely. In 2003, PEDIG investigators found that two hours of patching every day was as effective as six hours.
These results do not necessarily apply to all children with amblyopia. Children with more severe amblyopia, older children, and children who have amblyopia from causes other than crossed eyes or refractive error, may need a different treatment regimen. PEDIG is conducting research related to these groups, as well.
The IU School of Optometry was one of the 30 PEDIG clinical sites throughout North America that participated in the study.
After four months of treatment, children with moderate amblyopia who received the drop of atropine each weekend day showed the same improvement in vision as those who received the eye drop every day.
In the study, 168 children less than 7 years old with moderate amblyopia were randomly assigned to receive either weekend or daily atropine. The average age of the children was 5.3 years. Patients in both groups showed substantial improvement in the eye with amblyopia, averaging 2.30 lines of improvement following treatment. After four months, 72 percent of children in the weekend group and 73 percent of the patients in the daily group could read at least two more lines on the standard eye chart.
Vision in the unaffected eye decreased by two or more lines in about 2 percent of patients in the weekend group and about 3 percent of patients in the daily group. Vision in the unaffected eye is expected to return to normal when treatment is completed.
Researchers noted that the amount of vision improvement after four months in the eye with amblyopia should not be considered to be the maximum amount of improvement that can occur with atropine. Fifty-three patients had their study treatment continued beyond four months because they had improved, but the acuity was not equal to the unaffected eye. The extended treatment averaged 10 weeks, with an average improvement of 0.8 lines in each treatment group. Sixteen (52 percent) of the 31 patients in the weekend group and 10 (45 percent) of the 22 patients in the daily group improved at least one additional line of acuity in the amblyopic eye.
Dr. Lyon can be reached at 317-797-5269 and firstname.lastname@example.org.