Paper 22

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Injection of Bupivacaine and Botulinum Type A Toxin to Treat Strabismus

 Talita M. Cunha, MD; Joel M. Miller, PhD; Jian Guan, MD; Alan B. Scott, MD
Strabismus Research Foundation & Eidactics
San Francisco

Introduction:  Bupivacaine (BPX) elicits a type of damage similar to weight-bearing exercise, thereby correcting strabismus by strengthening and shortening injected muscles. Botulinum type A toxin (BTXA) in the antagonist allows the BPX-injected muscle to rebuild at reduced length. Here, we evaluate clinical effectiveness and long-term stability of corrections achieved in a large series of comitant horizontal strabismus cases, and present preliminary data on non-comitant and vertical strabismus.

Methods:  Seventy-four adult horizontal strabismus patients participated in a prospective observational clinical series. Five were non-comitant, and 28 had significant vertical components, including 4 with DVD. A second treatment was given to 30 of these patients who had residual strabismus after the first treatment. Eleven patients required additional injections. Doses per injection averaged 58mg for BPX and 2.3u for BTXA. Clinical alignment was measured at intervals, up to 10 yrs after treatment.

Results:  On average, misalignment of 24.5∆ (13.8°) was reduced by 17.5∆ (9.9°). Sixty-five percent of the 74 patients had successful outcomes (residual deviation ≤10∆) at average followup of 31mo.

Discussion:  Corrections were stable over followups as long as 10 yrs. Early in the series we favored low doses to avoid over-correction, which probably inflated the re-injection rate: on average, our earliest patients were 45% corrected with a single treatment (measured at 6mo), compared to recent patients who enjoyed 70% correction.

Conclusion:  Injection treatment for comitant horizontal strabismus achieves stable corrections comparable to surgery, and may also be effective in some types of non-comitant and vertical strabismus.

References:  Scott, A. B., D. E. Alexander and J. M. Miller (2007). ‘Bupivacaine injection of eye muscles to treat strabismus.’ Br J Ophthalmol 91(2): 146-148.
Scott, A. B., J. M. Miller and K. R. Shieh (2009). ‘Bupivacaine injection of the lateral rectus muscle to treat esotropia.’ Journal of AAPOS 13(2): 119-122.
Debert, I., J. M. Miller and A. B. Scott (2016). ‘Pharmacologic Injection Treatment of Comitant Strabismus. Journal AAPOS 20: 106-111

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