ABSTRACT
OBJECTIVE: To evaluate the effectiveness and safety of botulinum toxin A injection in treating overcorrected and undercorrected strabismus after unsatisfactory postoperative alignment. MATERIAL AND METHOD: The authors reviewed the outcomes of 20 patients aged 5 to 56 years (mean 29.1 years) who had botulinum toxin A injection following their unsatisfactory operation. The motor outcomes (percentage of successful motor outcome and percentage change in deviation) were recorded at 1 month, 3 months, 6 months, I year 2 years, 3 years, and 4 years after botulinum toxin injection. RESULTS: The mean pre-botulinum toxin injection angle of deviation was 20.6 prism dioptors (PD). Six of 20 (30%) patients maintained the successful position for the average of 2.66 years (range 1-4 years) with single injection. The mean percentage change of the deviation was 87.50%, 87.93 %, 73.05 % at 1, 2, and 3-year visit respectively. In 3 of 5 (60%) patients of consecutive esotropia, 4 of 8 (50%) residual esotropia, 1 of 4 (25%) of consecutive exotropia and 1 of 3 (33.33%) of residual exotropia had successful motor alignment at 6 month visit. There was no scleral perforation, visual loss, or retrobulbar hemorrhage from the injection treatment in the present study. CONCLUSION: Botulinum toxin A injection appears to be a safe and effective treatment for overcorrected and undercorrected strabismus after unsatisfactory surgery. It is very effective in rapid elimination postoperative diplopia. When the result is not adequate or the effect does not last long, repeat the injection or reoperation can be chose to perform later.