Use of Botulinum Toxin in Small-Angle Heterotropia and Decompensating Heterophoria: A Review of the Literature

Dose-Effect Relationship of Botulinum Toxin Type A in the Management of Strabismus: A Review

Botulinum toxin type A (BTXA) is a well-accepted non-surgical therapy for strabismus. However, its dose and technique vary widely. We reviewed published evidence on the dose effect of BTXA in treating various types of strabismus. Articles on BTXA therapy outcomes were reviewed to study doses and brands of BTXA used and their efficacy for specific types of strabismus. Researchers indicated that greater dosages may be used safely without increasing the risk of complications. The review suggested a positive dose-response relationship of BTX to success but with a higher risk of complications. No single dose of BTX could be recommended for strabismus management.

Application of Soft Directional Prismatic Contact Lenses to Correct Diplopia

PURPOSE

To verify whether diplopia due to a small-angle strabismus within 8 prism diopters (PD) could be corrected by applying soft directional prismatic contact lenses, obtaining higher comfort and quality of vision for the patients.

METHODS

A prospective study was undertaken by enrolling consecutive patients affected by vertical and/or horizontal diplopia and small-angle strabismus within 8 PD. The patients were tested for best corrected visual acuity, refraction, cover test for near and for distance, ocular motility test, prismatic fit test, corneal topography, tear film evaluation, binocular vision test, head position evaluation, retinography, and optical coherence tomography of the posterior and anterior segment. Custom soft contact lenses, made in Benz G5X material, were designed and developed for this study. All patients were first corrected with prismatic glasses according to their degree of strabismus and ametropia. Then they were asked to wear custom-made directional prismatic contact lenses with appropriate simultaneous correction of strabismus and ametropia. The patients were then asked to answer whether the comfort and quality of vision was higher with directional prismatic contact lenses or prismatic glasses.

RESULTS

Eight patients were enrolled with different causes of diplopia caused by a strabismus of 8 PD or less. The soft directional prismatic contact lenses could resolve diplopia in 100% of patients. All patients reported greater comfort and quality of vision with directional prismatic contact lenses.

CONCLUSIONS

The study demonstrated that diplopia resulting from an angle of strabismus within 8 PD can be corrected through the use of soft directional prismatic contact lenses, obtaining greater quality of vision free of aberrations. [J Pediatr Ophthalmol Strabismus. 20XX;X(X):XX-XX.].

Factors Affecting the Efficacy of Botulinum Toxin Injection in the Treatment of Infantile and Partially Accommodative Esotropia

PURPOSE

We aimed to investigate the effect of botulinum toxin (BT) injection on the treatment of infantile and partially accommodative esotropia (PAET).

METHODS

This retrospective cohort study included patients who received BT injections for infantile and PAET between January 2015 and December 2018. Treatment was considered successful if orthotropia, consecutive exotropia, or esotropia within 10 prism diopters (PD) was achieved.

RESULTS

The overall success rate was 47.4%, with a mean follow-up period of 27.8 months in 403 children. BT treatment was considered successful in 37.1% of cases of infantile esotropia and 53.1% of cases of partially accommodative esotropia. The average deviation angle before starting treatment was 35.5 ± 13.9 PD. Side effects 1 week after BT injections included transient overcorrection (63.8%) and transient ptosis (41.7%). There were no significant differences in the success rates between the different doses of BT (P = 0.69). The angle of deviation at presentation was significantly associated with the success rate of BT injection (failed group, mean: 38.1 ± 15.3 PD vs. success group, mean: 32.6 ± 11.6 PD; P < 0.001). Other factors associated with higher success rates were overcorrection at 1 week and PAET, while multivariate logistic regression analysis showed that a smaller angle of deviation and overcorrection (1 week after injection) were associated with a higher success rate.

CONCLUSION

A smaller angle of deviation and transient overcorrection were associated with a higher success rate, and no significant difference was observed in the success rates of different BT doses.

Short-term outcome of botulinum neurotoxin A injection with or without sodium hyaluronate in the treatment of infantile esotropia-a prospective interventional study

Purpose

To compare the short-term outcome of botulinum neurotoxin A (BoNT-A) with or without sodium hyaluronate in the treatment of infantile esotropia (IE).

Methods

In this tertiary care hospital-based prospective, interventional, non-randomized study on infants with IE below one year of age, 25 cases were enrolled in the sodium hyaluronate (SH) group to receive 2.5 U BoNT-A injection combined with SH in each medial rectus muscle (MR). Thirty patients were enrolled in the control group to receive 2.5 U BoNT-A injection with normal saline in each MR. The change in mean primary ocular deviation (POD) and complications were assessed at 2 weeks, 1 month, 3 months, and 6 months post injection. Mann-Whitney U test was used for non-parametric unpaired data. Chi-square test and Fisher's exact test were used to test for the strength of the association between the two categorical variables.

Results

Satisfactory ocular alignment was achieved in 76% in SH group and 73% in the control group (P value = 0.80). While the change in mean POD was comparable (29.2 prism diopters [PD] vs 29.3 PD; P value = 0.65), the complication rates were significantly lesser in SH (16% vs 33.3%; P value = 0.14).

Conclusion

BoNT-A combined with SH is equally effective with lesser complications as compared to botulinum toxin alone in the treatment of IE.

Ocular surface changes following botulinum toxin injection for strabismus

CONTEXT

Botulinum toxin injection is widely used for many purposes, including neuromuscular diseases, movement disorders and strabismus.

OBJECTIVE

To evaluate and report the impact of botulinum toxin injection on ocular surface parameters in patients with strabismus.

PARTICIPANTS

Twenty-six consecutive patients who underwent botulinum toxin A injection for ocular misalignment were recruited for this prospective study.

MATERIALS AND METHODS

Testing of ocular surface parameters including tear break-up time (BUT), lissamine green (LG) staining and Schirmer test (under topical anesthesia) was performed, and Ocular Surface Disease Index (OSDI) questionnaire scores were recorded before and at certain time points after injection (one week, two weeks, one month, three months and six months after botulinum toxin A injection). Two-way analysis of variance (ANOVA) with repeated measures, Friedman's test and Wilcoxon test were used for statistical analysis.

RESULTS

Twenty six patients (15 eso- and 11 exo-deviations) with a mean age of 32.46 ± 14.41 (17-65) years were recruited for the study. All injections were performed in one eye. The mean amount of deviation at near and distance reduced after injection. The change of BUT, LG staining and OSDI scores was found to be significant during follow-up in treated eyes (p = 0.001, p = 0.007 and p = 0.009, respectively) whereas the change was insignificant for the Schirmer test results (p = 0.266).

CONCLUSIONS

The ocular surface parameters appear to be altered by botulinum toxin injection in strabismic patients. Even though these effects seemed to be temporary, the findings of the present study support the notion of botulinum toxin effects on ocular surface parameters.

Monovision correction for small-angle diplopia

PURPOSE

To assess quantitatively the efficacy of monovision correction in the treatment of acquired small-angle binocular diplopia in adult patients.

DESIGN

Prospective, interventional case series.

METHODS

Twenty patients with symptomatic diplopia were enrolled in a prospective treatment trial at a tertiary university neuro-ophthalmology practice. All had stable deviations of 10 prism diopters or less for more than 3 months. Each received monovision spectacles, contact lenses, or both with distance correction in the dominant eye. Half received a +3.00-diopter add and the others received +2.50 diopters. The validated and standardized Diplopia Questionnaire and Amblyopia and Strabismus Questionnaire were used to quantify the efficacy of monovision correction for diplopia by measuring the functional impact on vision-specific quality of life.

RESULTS

primary outcome: Based on the results of the Diplopia Questionnaire, 85% of patients experienced significant improvement in diplopia symptoms after monovision correction. There was a statistically significant 58.6% improvement in the Diplopia Questionnaire score in our patients (P < .0001). secondary outcome: The Amblyopia and Strabismus Questionnaire scores demonstrated improved quality of life and daily function after monovision correction (P = .03), especially in the areas of double vision(P = .0003) and social contact and appearance (P = .0002).

CONCLUSIONS

Monovision decreased the frequency of diplopia and improved subjects' quality of life. Monovision may be a feasible alternative for presbyopic diplopic patients who are dissatisfied with other conservative treatment options.

Long-term results of botulinum toxin-augmented medial rectus recessions for large-angle infantile esotropia

PURPOSE

To evaluate the long-term results of medial rectus recessions augmented by botulinum toxin injection for treating infants with large-angle (> 60 prism diopters [PD]) infantile esotropia.

DESIGN

Interventional case series.

METHODS

SETTINGS

Hospital-based clinical practice.

PATIENT POPULATION

Twenty-three patients with large-angle infantile esotropia who were followed for at least 2 years postoperatively.

INTERVENTION

Surgical treatment with botulinum toxin in addition to bilateral medial rectus muscle recessions. The preoperative findings, treatment, and outcomes were reviewed.

MAIN OUTCOME MEASURES

Surgery was considered successful if the patients did not require additional horizontal strabismus surgery and had less than 10 PD of horizontal deviation.

RESULTS

The age at surgery ranged from 4 to 36 months (mean 14.5 months) and the angle of esotropia ranged from 65 to 100 PD (mean 72 PD). Treatment was successful in 17 of 23 patients (74%), with follow-up of 2 to 13 years (mean 6.6 years).

CONCLUSION

Botulinum toxin-augmented medial rectus recession is an effective treatment for large-angle infantile esotropia, with stable results over time.

Complications of botulinum toxin a and their adverse effects

AIM

To evaluate the prevalence of complications after low doses (< 3 units) of botulinum toxin (BT) injection to horizontal extraocular muscles for diagnostic and therapeutic purposes.

METHODS

A case record review was undertaken of patients treated with BT (Dysport) since 2000. Data were extracted for gender, age, diagnosis, number of BT injections, dose, recorded complications, and time to recovery.

RESULTS

Two hundred eleven (211) cases were reviewed, 48.5% children, 51.5% adults (45.5% male, 54.5% female). Diagnoses included constant and intermittent esotropia and exotropia, decompensating esophoria, exophoria and microtropia, accommodative spasm, mechanical restrictions, and cranial nerve palsy. One hundred sixty-three (163) patients had one injection; 38 had two; 7 had three; 2 had four; 1 had six; for a total of 274 injections. BT dose was 1 unit in four cases; 2.5 units in two; 3 units in seven; and 2 units in the remainder. At 2 weeks follow-up, six cases had induced vertical deviation; three had subconjunctival haemorrhage. At 2 weeks, 23 cases had ptosis, but a further 10 cases had ptosis that had resolved by 2 weeks follow-up. All complications had resolved by 6 weeks follow-up.

CONCLUSIONS

A low incidence of complications per injection (12.4%) was found particularly for induced vertical deviations (2%) and hemorrhages (1%). Incidence for ptosis was the highest (8.4%). Notably, 10 additional cases of ptosis had resolved before follow-up. Two children were given occlusion therapy to prevent the possibility of stimulus deprivation occlusion until ptosis resolution.