An Evaluation Of Treatment Of Amblyopia In Children 7 To <18 Years Old

• To determine the response rate of treatment of amblyopia in 7 to <18 year olds
• To determine the frequency of recurrence of amblyopia in 7 to <18 year olds after discontinuation of amblyopia treatment

Most eye care practitioners believe that there is an age beyond which attempting to treat amblyopia is futile. It is generally held that the response to treatment is best when it is instituted at an early age and is poor when attempted after eight years of age. There has not been a prospective clinical trial conducted with appropriate rigor that has evaluated the effect of treatment of amblyopia in children aged 7 years or older. Although available data on the efficacy of amblyopia treatment of older children are limited, there is reason to believe from clinical observations and published case series that treatment could have benefit. In a pilot study of patients 10 to <18 years old with amblyopia, we found that 37 percent of 52 patients showed improvement in the amblyopic eye acuity of 2 or more lines after treatment with part-time patching. However, without a concurrent randomized control group, the results are not conclusive. Although the literature and our pilot study provide support that amblyopia can be improved with treatment, neither the response rate to treatment nor the recidivism rate after cessation of treatment can be well defined. Despite the evidence that amblyopia therapy can be effective in older children, many clinicians do not attempt treatment under the assumption that it will be unsuccessful. Therefore, a clinical trial is needed to provide the requisite data to establish clinical practice guidelines for the treatment of amblyopia in older children. In addition to its importance for patient management, the trial’s results will meet the demand for cost efffectiveness by health maintenance organizations, large employers, and insurers.

The randomized trial was designed to compare patients treated with spectacles only to patients treated with active treatment in addition to spectacles. The recruitment goal was to enroll a minimum of 90 patients in each of the age groups of 7 to <9, 9 to <11, 11 to <13, and 13 to <18 years old. Patients had follow up visits every 6 weeks (up to a maximum of 24 weeks) until they were classified as either responders or nonresponders based on amblyopic eye visual acuity.

At the end of the randomized trial:

• Patients who did not respond to treatment ended follow up
• Patients who responded to treatment continued in their respective treatment groups until visual acuity stopped improving.

• Patients in the Optical Correction Group ended follow up
• Patients in the Treatment Group discontinued active treatment and entered an observation phase. This phase of the study is currently ongoing. Patients have follow up visits at 13 weeks, 26 weeks, and 52 weeks timed from treatment discontinuation.

Patients must be aged 7 to <18 years and have amblyopia associated with strabismus, anisometropia, or both. Visual acuity in the amblyopic eye must be 20/40 to 20/400 inclusive and visual acuity in the sound eye must be 20/25 or better. Patients must not have received amblyopia treatment (other than spectacles) in the past month or more than one month of amblyopia treatment in the last 6 months.

No longer recruiting. Comments: Completed. Recruitment began in October 2002 and closed March 2004 after 507 patients were randomized.

Completed, with results published. Comments: The randomized trial results have been completed. Follow up of patients in the observation phase was completed in December 2005.

Summary of Randomized Trial Results:

In a randomized multi-center clinical trial, 507 children 7 to less than 18 years of age with amblyopia in the range of 20/40 to 20/400 were provided with optimal optical correction and then assigned to either prescription of additional treatment (2 to 6 hours per day of prescribed patching combined with near visual activities for all patients plus atropine for 7 to <13 year olds) or optical correction alone. Patients whose amblyopic eye acuity improved 10 or more letters (2 lines) by 24 weeks were considered responders.

In the 7 to <13 year olds, 53% of the treatment group were responders compared with 25% of the optical correction group (P<0.001). In the 13 to <18 year olds, the responder rates were 25% and 23% respectively overall (adjusted P=0.22), but 47% and 20% respectively among patients not previously treated with patching and/or atropine for amblyopia (adjusted P=0.03). Most patients, including responders, were left with a residual visual acuity deficit.

For patients 7 to <13 years old, prescribing 2 to 6 hours per day of patching with near activities and atropine can improve visual acuity even if the amblyopia has been previously treated. For patients 13 to <18 years old, prescribing patching 2 to 6 hours per day with near activities may improve visual acuity when amblyopia has not been previously treated but appears to be of little benefit if amblyopia was previously treated with patching.

We do not yet know whether visual acuity improvement will be sustained once treatment is discontinued; therefore, conclusions regarding the long-term benefit of treatment and the development of treatment recommendations for amblyopia in children 7 years and older await the results of a follow-up study we are conducting on the patients who responded to treatment.