Occlusion Versus Pharmacologic Therapy for Amblyopia (Patch v. Atropine)

A Randomized Trial Comparing Occlusion Versus Pharmacologic Therapy for Moderate Amblyopia (Patch v. atropine)

Amblyopia, when diagnosed in children, is usually treated with occlusion (patching) of the sound eye. Occlusion therapy is subject to problems of compliance, due to the child’s dislike of wearing a patch for visual, skin irritation, and social/psychological reasons. There is evidence that compliance may be one of, if not, the most important determinant of success of amblyopia therapy.

An alternative treatment, drug therapy with a cycloplegic drug (atropine) that dilates the pupils and blurs the image seen by the sound eye, has been known for almost a century. This method has been widely used for the management of occlusion treatment failures and for maintenance therapy. However, it has seen little use as a primary treatment for amblyopia. Clinical experience has found that it has a high acceptability to patients and parents, and hence high compliance. In addition to its acceptability, pharmacologic therapy has the known advantage over occlusion of providing a wider visual field with both eyes, which may have safety and other functional implications. There is also clinical and laboratory evidence suggesting that drug therapy may maintain and improve the ability to see with both eyes (binocularity).

Available data suggest that the success rate with drug therapy is as good as, if not better than, the success rate with occlusion therapy for mild to moderate degrees of amblyopia. If this is true, for many children with amblyopia, drug therapy may be the preferred initial therapy since it appears to be more readily accepted by the children and parents. Despite data to support the use of drug therapy as a primary therapy for amblyopia, it has gained only limited use among pediatric ophthalmologists. The NEI conducted this study comparing the outcomes from occlusion therapy and drug therapy to determine if new practice guidelines for treatment of amblyopia are needed.

The study compared the effectiveness of 6-month treatment of occlusion with eye patches with a 6-month treatment with daily topical 1% atropine sulfate eye drops.

Patching Protocol
Adhesive skin patches provided by the study (Coverlet Eye Occlusors; Beiersdorf-Jobst Inc, Rutherford College, NC) were used unless there was skin allergy or irritation nonresponsive to both local treatment with a skin emollient and a change in the brand of patch, in which case a spectacle occluder could be prescribed.

The patching protocol was designed to be similar to the investigator's usual practice subject to the following stipulations: (1) the initial patching time was a minimum of 6 hours per day (maximum, all waking hours); (2) assuming that reverse amblyopia did not develop, this minimum remained in effect through the 6-month outcome examination unless the criteria for successful treatment were met; (3) if criteria for successful treatment were met, patching time could be reduced but needed to be at least 7 hours per week as long as the visual acuity in the amblyopic eye was 1 or more lines worse than that in the sound eye; (4) if the visual acuity in the two eyes became equal, patching could be discontinued; and (5) if criteria for successful treatment were not met by the 16-week visit, and patching time had been less than 12 hours per day, patching time was increased to 12 or more hours per day for 2 months prior to the 6-month outcome examination.

Atropine Protocol
At enrollment, patients were prescribed 1 drop per day of atropine sulfate 1%, which was provided by the study. Sunglasses were also provided, with the advice that they be worn with a hat when the child was in sunlight. Daily atropine use was continued unless the visual acuity in the amblyopic eye met criteria for successful treatment, in which case (at the investigator's discretion) the frequency could be reduced to a minimum of 2 times a week and could be discontinued if the acuities became equal in the two eyes. For patients with hyperopia in the sound eye, if the amblyopic eye was not successfully treated by the 16-week visit, the spectacle lens was reduced to plano for 2 months prior to the 6-month outcome examination.

If an allergy to atropine developed, topical homatropine 5% could be substituted instead.

Study Results: The study found that At 2 years, visual acuity in the amblyopic eye improved from baseline a mean of 3.7 lines in the patching group and 3.6 lines in the atropine group. There were no meaningful difference between groups in either mean visual acuity score or lines of improvement. The distributions of outcome acuities in the amblyopic eyes were remarkably similar, with 51% in the patching group and 49% in the atropine group achieving 20/25 or better.

Study Conclusion: Atropine or patching for 6 months produced similar improvement of moderate amblyopia in children between 3 and 7 years of age.

Email to contact the study group: pedig@jaeb.org

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