APR 11, 2014
Pediatric Ophth/Strabismus
This prospective study confirmed the effectiveness of bupivacaine injection in comitant horizontal strabismus and found that it induces changes in rectus muscle structure and length.
Subjects included 31 patients: 19 with esotropia who received bupivacaine injections in the lateral rectus muscle and 12 with exotropia who received bupivacaine injections in the medial rectus. Sixteen of these patients had large strabismus angles and received Botox in the antagonist muscle during the same treatment session. A second treatment was given to 13 patients who had residual strabismus after the first treatment.
At an average of 15.3 months after the final treatment, original misalignment was reduced by 10.5 prism diopters, with residual deviations of 10Δ or less in 53 percent of patients. A single treatment with bupivacaine alone reduced misalignment at 11.3 months by 4.7Δ with residual deviations of 10Δ or less in 50 percent of patients. These corrections remained remarkably stable over follow-ups for as long as three years.
Six months after bupivacaine injection, MRI showed that extraocular muscle volume had increased by 6.6 percent and maximum cross-sectional area had increased by 8.5 percent, gradually relaxing toward pretreatment values thereafter. Computer modeling with Orbit 1.8 (Eidactics) suggested that changes in agonist and antagonist muscle lengths were responsible for the enduring changes in eye alignment.
The authors conclude that bupivacaine injection is a useful treatment for nonparalytic strabismus when surgery is contraindicated. Ongoing refinements are expected to increase its effectiveness and broaden its applications.