The efficacy of bupivacaine for the treatment of strabismus

Abstract

Introduction: Bupivacaine (BPX) is a widely used local anesthetic. Ophthalmologists have found a unique use of BPX to alter the elasticity and contractile properties of extraocular muscles to straighten strabismus. The utilization of BPX to treat strabismus has been well documented. The purpose of this review is to examine the overall efficacy of BPX when used in isolation for the treatment of strabismus, based on the published literature. Methodology: A literature search was carried out to identify papers published between the years 1980 and 2021, which examined the impact of BPX as a stand-alone treatment for strabismus. Results: Eight articles were identified as matching the inclusion criteria. The authors reported that volumes of ≤1.00 mL are unlikely to be significant enough to improve ocular alignment and increasing volume strength is associated with greater changes in ocular alignment. The overall change in ocular alignment varied from 0–16PD between the different studies included, with similar effects being noted for deviations between 10 and 20PD and deviations as large as 55PD. It has been documented that there is no significant difference in the outcomes of BPX treatment for esotropia and exotropias, but some clinical differences have been noted with esotropia (or the lateral rectus) responding better to BPX. Bupivacaine has been demonstrated to be less effective in patients with chronic nerve palsies. All but one author documented increases in the injected muscle’s volume and maximum cross-sectional area from month one to three followed thereafter by a gradual decrease in both measurements. It was noted that despite the reduction in both measurements, the change in ocular alignment continued to show improvements. No sight-threatening or persistent complications were reported within any of the studies or case reports included within this review. In the interest of patient experience, the majority of patients reported that BPX improved their eye alignment, while a third reported feelings of discomfort during the procedure. Conclusion: Bupivacaine is a viable option for the treatment of small angle deviations and is not recommended for use in long-standing cranial nerve palsies or those associated with atrophy. Care is needed in determining the required dose to avoid the need for re-injection and impacting patient experience.