Amblyopia treatment: 2 hours of patching as effective as 6 hours, study shows

Experts suggest amended guidelines for treatment could improve compliance and reduce psychological trauma associated with wearing the patch.

Issue: July 1, 2003

ByNicole Nader

BETHESDA, Md. — Better compliance and happier children may be the results of a recent study of amblyopia.

A study by the Pediatric Eye Disease Investigator Group (PEDIG) found that patching the unaffected eye of a patient with moderate amblyopia for 2 hours daily is as effective as patching the eye for 6 hours.

In the study, amblyopia improved with both patching regimens. “There was no demonstrable advantage to the greater number of patching hours, either in rapidity of improvement or in the magnitude of improvement,” the study authors noted.

In addition, no indication was found to suggest that 6 hours of patching, compared with 2 hours, was associated with a higher rate of adverse effects on the visual acuity of the sound eye, ocular alignment or binocularity.

With a shorter therapy session time now possible, better patient compliance may be expected, according to a press release from the National Eye Institute (NEI), which sponsored the study.

“These results will change the way doctors treat moderate amblyopia and make an immediate difference in treatment compliance and the quality of life for children with this eye disorder,” said Paul A. Sieving, PhD, MD, director of the NEI. The impact of these findings will be significant, he said, considering that the NEI estimates as many as 3% of U.S. children have “some degree” of vision impairment due to amblyopia.

One of the advantages of the shorter treatment regimen may be reduced psychological trauma associated with wearing the patch. Because children can complete their patching at home, they may avoid the social stigma of wearing a patch to school.

Study criteria

The social stigma of wearing a patch to school may be avoided with shorter patching schedules, the study authors suggest.

For the clinical trial, PEDIG recruited 189 patients from 35 university- and community-based practices in the United States.

Eligibility criteria included children under 7 years of age with visual acuity in the amblyopic eye of 20/40 to 20/80. Visual acuity in the sound eye had to be 20/40 or better. The inter-eye acuity difference was at least 3 lines of logMAR visual acuity, the study authors reported.

Children with amblyopia secondary to strabismus, anisometropia or a combination of both were included only if they qualified under specific study guidelines for each condition. Any presence of ocular abnormalities reducing visual acuity, myopia of 6 D or greater, prior IOL surgery or known skin irritation/reaction to the patch eliminated patients from the study cohort.

In total, 95 patients were randomly assigned to wear a patch for 2 hours a day and 94 to wear a patch for 6 hours a day.

Parents were requested to have their child wear the patch continuously and spend at least 1 hour with the patch on doing near-visual activity. Near-visual activity included drawing, coloring, tracing objects, connecting the dots, playing computerized games, reading and writing.

The treatment period lasted for 4 months. Follow-up visits were conducted at 5 weeks and 17 weeks after the onset of patching. At the 5-week period, parents answered questionnaires to assess the effect of amblyopia treatment on their and their child’s quality of life. Additionally, parents submitted a calendar, which logged the hours that their child was patched daily. Calendars were assessed by researchers for adherence to treatment protocol.

At 4 months, patients underwent a final outcome examination. Visual acuity was tested, in addition to ocular alignment and stereoacuity, in a test-certified center.

Visual outcomes

After 4 months of follow-up, 97% of patients in the 2-hour group and 95% in the 6-hour group completed the primary outcome exam.

Patients in both groups showed substantial improvement in the eye with amblyopia, averaging 2.4 lines of improvement from baseline. Visual acuity measurements of 20/32 or better and 3 or more lines of improvement from baseline were achieved by 62% of patients in both groups.

Assessment of patients’ ocular alignment found that one patient in each group developed intermittent exotropia at distance fixation during the 4-month follow-up. Additionally, four patients in the 2-hour group and one patient in the 6-hour group had existing esotropia that increased during patching.

Binocularity testing showed that there was no difference between groups in patient responses for Randot Stereotests, random dot shapes tests or the Randot Preschool Stereoacuity Test.

Adherence

Patient adherence to therapy was considered excellent in 58% of the 2-hour group and 37% of the 6-hour group. In the 2-hour group, 25% of patients were rated as good in their compliance, 14% as fair and 3% as poor.

Compliance outcomes were poorer in the 6-hour patching group, in which 37% of patients were rated as good, 15% as fair and 11% as poor.

Additionally, parents from the 6-hour group expressed a significantly higher amount of concern with the social stigma associated with wearing the patch than parents of children from the 2-hour group.

For Your Information:

Paul A. Sieving, PhD, MD, can be reached at the National Eye Institute, 2020 Vision Place, Bethesda, MD 20892-3655; (301) 496-2234; fax: (301) 496-9970; Web site: www.nei.nih.gov.

Reference:

The Pediatric Eye Disease Investigator Group. A randomized trial of patching regimens for treatment of moderate amblyopia in children. Arch Ophthalmol. 2003;121:603-611.