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The minimum occlusion trial for the treatment of amblyopia
Ronald V Keech1, Wanda Ottar, Linna Zhang
1Department of Ophthalmology, University of Iowa, Iowa City, Iowa. Shandong Medical University, Shandong, People's Republic of China. ronald-keech@uiowa.edu
Objective:
To determine whether the traditional regimen of three intervals of full-time occlusion (FTO) for amblyopia without any measurable improvement in visual acuity constitutes an adequate trial.
Design:
Retrospective, noncomparative, interventional case series.
Participants:
Sixty-four children younger than 10 years of age with unilateral amblyopia.
Methods:
The medical records of patients treated for amblyopia in a university outpatient clinic were reviewed. Patients who underwent one FTO interval without an improvement in visual acuity followed by at least one additional FTO interval were included in the study.
Main Outcome Measures:
Improvement in visual acuity.
Results:
Sixty-four patients underwent 81 occlusion trials consisting of one FTO interval without improvement followed by one or more FTO intervals. Visual acuity improved after the second FTO interval in 25 (31%) of the trials. Of the 44 occlusion trials consisting of two FTO intervals without improvement, visual acuity improved after the third FTO interval in 12 (27%) of the trials. Of the 11 occlusion trials consisting of three FTO intervals without improvement followed by one or more additional FTO intervals, acuity did not improve with any of the trials.
Conclusions:
A minimum of three intervals of FTO is necessary to determine whether an amblyopia patient will be unresponsive to occlusion therapy. After three FTO intervals without improvement, additional FTO is unlikely to result in an improvement in visual acuity.