Recruitment began in October 2002 and closed March 2004 after 507 patients were randomized. The randomized trial results have been completed. Follow up of patients in the observation phase will continue through the fall of 2005.
- 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
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
Once there was no further improvement in visual acuity:
- 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.
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.
Summary of Observational Phase Results:
During the year following cessation of treatment, the cumulative probability of worsening acuity (2 or more lines) was 7% (95% confidence interval 3% to 17%); 82% of patients maintained an increase in acuity of 10 or more letters compared with acuity prior to starting treatment.
Visual acuity improvement occurring during amblyopia treatment is sustained in most 7 to 12 year olds for at least one year after discontinuing treatment other than spectacles. The data support the treatment of 7 to 12 year olds with amblyopia by demonstrating that acuity improvement can be maintained after treatment is discontinued.