Mary G. Tucker

Incidence of stereopsis after treatment of infantile esotropia with botulinum toxin A.

PURPOSE: The incidence of stereoscopic vision following surgery for infantile esotropia has been reported, but not from patients treated with simultaneous bimedial injection of botulinum toxin A. We previously reported other findings from 41 patients treated with botulinum toxin A before the age of 12 months. The purpose of this study was to report the incidence of stereopsis in these patients after long-term follow-up. PATIENTS AND METHODS: Data were acquired by recording the response to subjective stereoscopic testing during the postinjection follow-up period when reliable subjective responses could be obtained. At least 5 years had passed following injection, and the mean age of the patients was 8 years. RESULTS: Of the 41 patients, 11 were lost to follow-up, 10 had no stereopsis, 9 had gross stereopsis (according to Titmus fly tests), 1 had 800 seconds of stereoscopic vision, 2 had 400 seconds, 2 had 200 seconds, 1 had 60 seconds, and 5 had 40 seconds. CONCLUSIONS: In this study, two-thirds of the patients acquired stereopsis following simultaneous bimedial injection of botulinum toxin A for infantile esotropia. Stereopsis acquisition following injection of botulinum toxin A had a success rate comparable with that reported for surgically corrected infantile esotropia. Bimedial injection of botulinum toxin A accompanied by alternate patching prior to injection and diligent attention at ages ranging from 4 to 12 months is a simple and efficacious method for the management of infantile esotropia.

Comparison of botulinum toxin with surgery as primary treatment for infantile esotropia

PURPOSE To compare bilateral medial rectus muscle injection of botulinum toxin with surgery as primary treatment for infantile esotropia. METHODS A single-center, prospective, nonrandomized comparative study was undertaken of botulinum toxin versus surgery in children who presented by age 36 months with esotropia onset before 12 months. Successful outcome was defined as ocular alignment within 10Delta of orthotropia after one surgery or 1 to 3 bilateral botulinum injections. RESULTS Of 442 subjects, 322 received botulinum toxin (1 injection, 49%; 2, 41%; 3, 10%); 120 had surgery. Motor success was achieved in 66% of surgery patients, compared with 45% of botulinum patients (p < 0.001). Among subjects with deviation >30Delta, surgery achieved 69% success versus 36% with botulinum toxin (relative risk, 1.95; 95% CI, 1.53-2.49). At deviations < or = 30Delta, there was no difference (surgery, 60%; botulinum toxin, 59%; relative risk, 1.03; 95% CI, 0.78-1.35). There were no statistically significant differences in mean pretreatment deviation (botulinum toxin, 38.8Delta; surgery, 38.2Delta) or mean follow-up (botulinum toxin, 22.6 months; surgery, 20.7). Surgery occurred later than botulinum injection (mean age at treatment, 27.0 vs. 16.7 months; p < 0.001) with greater duration of misalignment (21.0 vs 12.5 months, respectively; p < 0.001), but neither variable influenced outcome in multivariate regression. CONCLUSIONS In this large, nonrandomized prospective cohort, surgery was more successful than botulinum toxin in the treatment of large-angle esotropia. Botulinum toxin appeared most effective for esotropia <30Delta to 35Delta, with a success rate comparable with surgery. Botulinum toxin may be an alternative to surgery in children with small- to moderate-angle infantile esotropia.

Botulinum Toxin Management of Childhood Intermittent Exotropia

OBJECTIVE Intermittent exotropia is a common form of childhood strabismus that has a late onset and presents a difficult and frustrating management dilemma. Surgical treatments have a high recurrence rate, and multiple surgeries often are required to achieve a desirable motor outcome. This study presents long-term observations on the use of botulinum toxin for the treatment of intermittent exotropia in children. DESIGN This study is a nonrandomized, case-controlled study of consecutive pediatric patients who had intermittent exotropia. PARTICIPANTS Thirty-two neurologically normal children ranging from 3 to 144 months in age were diagnosed with intermittent exotropia with a minimum distance deviation of 15 prism diopters (PD). INTERVENTION Simultaneous bilateral injections of 2.5 units botulinum toxin type A were made into the lateral rectus muscles with the patient receiving nitrous oxide-ethrane inhalation anesthesia. Patients were observed for 12 to 44 months after the initial injection. MAIN OUTCOME MEASURES A satisfactory outcome was considered to be stable binocular alignment of the eyes to an orthophoric range of +/-10 PD. RESULTS Bilateral lateral rectus muscle injections of botulinum toxin were effective in reducing the mean preinjection deviation of -29 PD to an average exotropic angle of -6 PD. Stable orthophoria (+/-10 PD) was achieved in 22 patients (69%). Overall, male patients required significantly fewer injections than did female patients. All patients between 24 and 56 months of age, irrespective of gender, required only a single bilateral injection to achieve a favorable motor outcome. CONCLUSIONS Botulinum toxin is at least as effective as surgical outcomes reported previously for the treatment of intermittent exotropia in children. This treatment method is particularly effective in children between 2 and 4.5 years of age irrespective of the initial strabismic angle and is not associated with any secondary abnormalities.

Observations on bilateral simultaneous botulinum toxin injection in infantile esotropia.

Botulinum toxin (BoTX) is an effective pharmacological alternative to the surgical management of strabismus in adults. In a previous study, we found that concurrent bilateral medial rectus muscle BoTX injections for infantile esotropia could produce stable ocular realignment without significant risk. No other investigators have used bilateral simultaneous BoTX injection. We report the results of bilateral simultaneous medial rectus BoTX injection in 57 infantile esotropia patients followed for a minimum of 12 months. The esotropic angle in 27 infantile esotropia patients under 12 months of age was reduced from 43 +/- 12 to 1 +/- 2 prism diopters. The esotropic angle in 30 infantile esotropia patients at a mean age of 24 months was reduced from 31 +/- 12 to 2 +/- 3 delta. Other variables including late onset of hyperopic refractive errors, dissociated vertical deviations, overacting oblique muscles, and consecutive exodeviations are evaluated. We regard BoTX as reliable therapy in infantile esotropia.

Therapeutic application of botulinum toxin A in infantile esotropia

Botulinum toxin A (BTA) was originally developed as an alternative to surgery in treating infantile esotropia. Many therapeutic uses have since evolved based on the induced temporary muscle paralysis in skeletal muscle following BTA injection. Eye muscles are histologically and functionally different from skeletal muscle. Upon recovery from temporary paralysis, extraocular muscle length/tension parameter readjustment driven by normal visual feedback is permanent. This phenomena is especially powerful in the visual development period of infancy and early childhood where innate capacity of the CNS to drive misaligned eyes to a normal alignment is very dominant. Our reports showed simultaneous BTA injection into the medial rectus muscle of both eyes during the visual development period produces stable long-term binocular alignment.