Botulinum Toxin Injection for the Management of Refractory Filamentary Keratitis

Objective To evaluate the efficacy of onabotulinumtoxinA injection for the treatment of refractory filamentary keratitis. Methods A retrospective review of treatment response of 33 eyes of 17 patients with filamentary keratitis resistant to conventional medical therapy who were treated with onabotulinumtoxinA injection was performed. Ocular surface findings, symptom improvement, and the number and location of filaments before and after the injections were recorded. All eyelids were injected subcutaneously with onabotulinumtoxinA (10 U/0.1 mL). All treatments were performed in accordance with an individualized treatment plan using precise localizing treatment maps, with adjustments to dosage based on treatment response. Results Objective and subjective improvement was noted after the initial onabotulinumtoxinA injection in all patients. Filaments completely resolved after the onabotulinumtoxinA injection in 29 eyes (88%). In 20 of these eyes, filaments and punctate fluorescein staining resolved, whereas in 9 eyes, filaments resolved but punctate fluorescein staining persisted. Three eyes (9%) had partial improvement: 2 residual microfilaments were noted in one eye and 1 in the other eye. In 1 eye, filaments resolved after initial and subsequent injections but recurred within 8 weeks of each injection. Although 14 treated eyes (42%) showed sustained improvement after 1 onabotulinumtoxinA injection, additional injections were necessary in 19 eyes (58%) during the follow-up period because of the recurrence of symptoms and filaments on the cornea. Conclusions OnabotulinumtoxinA injection should be considered an effective option for treating refractory filamentary keratitis. Because of the likelihood of recurrence, serial onabotulinumtoxinA injections may be necessary in some cases.