Pharmacologic injection treatment of comitant strabismus

To report the magnitude and stability of corrections in comitant horizontal strabismus achieved by injecting bupivacaine (BPX, optionally with epinephrine) and botulinum A toxin (BTXA) into extraocular muscles of alert adult subjects with electromyographic (EMG) guidance.

A total of 55 adults with comitant horizontal strabismus participated in a prospective observational clinical series. Of these, 29 previously had undergone 1 or more unsuccessful strabismus surgeries; 4 had undergone other orbital surgeries. Thirty-one patients with esodeviations received BPX injections in a lateral rectus muscle, some with BTXA in the medial rectus; 24 patients with exodeviations received BPX in a medial rectus muscle, some with BTXA in the lateral rectus muscle. A second treatment (BPX, BTXA, or both) was administered to 27 patients who had residual strabismus after the first treatment. Five patients required additional injections. Clinical alignment was measured at 6 months and yearly thereafter through 5 years' follow-up, with mean follow-up of 28 months. A successful outcome was defined as residual deviation ≤10(Δ).

On average, presenting misalignment of 23.8(Δ) (13.4°) was reduced at 28 months by 16.0(Δ) (9.1°), with successful outcomes in 56% of patients. Of patients with initial misalignments ≤25(Δ), 66% had successful outcomes, with corrections averaging 13.2(Δ) (7.5°); of patients with larger misalignments, 40% had successful outcomes, with corrections averaging 20.9(Δ) (11.8°). Corrected alignments were stable over follow-ups as long as 5 years.

Injection treatments resulted in stable, clinically significant corrections in comitant horizontal strabismus. Injection provides a low-cost alternative to incisional strabismus surgery, particularly where it is desirable to minimize surgical anesthesia and avoid extraocular scarring.