Factors influencing success and dose-effect relation of botulinum A treatment

Botulinum Toxin Injection versus Extraocular Muscle Surgery for Acute Acquired Comitant Esotropia

Purpose

To compare the success rate of extraocular muscle surgery and botulinum toxin injection for treatment in patients with acute acquired comitant esotropia (AACE).

Patients and Methods

This is a retrospective cohort study in which we treated 34 patients of AACE with botulinum toxin compared with 80 patients who had been treated with surgery. The data included angle of deviation in prism diopter (PD) at baseline and one, three, and six months after treatment. The main outcome was the success rate in each treatment group.

Results

In the surgery group, mean esodeviation angles at baseline and one, three, and six months after treatment were 50.8 ± 18.3 PD, 4.9 ± 8.3 PD, 4.6 ± 9.5 PD, and 5.5 ± 10.3 PD, whereas those in the botulinum toxin group were 51.2 ± 14.3 PD, 13.9 ± 17.4 PD, 22.0 ± 19.3, and 31.3 ± 23.8 PD, respectively. There was a statistically significant difference in the deviation angles between the two groups (p < 0.001). The success rate in the surgery group at one, three, and six months was 81%, 84%, and 79%, whereas that in the botulinum toxin group was 50%, 27%, and 27%.

Conclusion

Botulinum toxin injection was not as effective as conventional extraocular muscle surgery in AACE patients. However, the treatment is safe, fast-acting, and improves both cosmetic appearance and quality of life. This may be considered as a chance for patients not preferring surgery.

Comparison of Dose Increments of Botulinum Toxin A with Surgery as Primary Treatment for Infantile Esotropia and Partially Accommodative Esotropia

Purpose

To compare the effect of increment dose of botulinum toxin (BTX) injection in correlation to the angle of deviation to bilateral medial rectus recession (BMR) in infantile esotropia and partially accommodative esotropia (PAET).

Methods

This was a retrospective study that included pediatric patients ≤16 years old with infantile esotropia and PAET at Dhahran Eye Specialist Hospital (DESH) from 2014 till 2021 treated with increment dose of BTX or BMR. A successful outcome is defined as ocular alignment within 10 PD of deviation after 1–3 BTX injections or one surgery with a minimum follow-up of 6 months.

Results

Of 177 patients, 101 patients received BTX treatment for either infantile esotropia (n = 37) or PAET (n = 64) and 76 patients underwent BMR for either infantile ET (n = 25) or PAET (n = 51). BTX showed a higher success rate than BMR {65.3% vs 55.3% (p = 0.174)}. In patients with infantile esotropia, the success rate was comparable between BTX group and BMR group {40.5% vs 52% (p = 0.440)}. However, the success rate was statistically significantly higher in BTX group in compare to BMR group {79.7% vs 56.9% (p = 0.014)}. Consecutive exotropia was 0% in BTX group and 9.2% in BMR group (p = 0.002).

Conclusion

The increment dose of BTX injection is comparable to surgery in patients with infantile esotropia but superior to the routine surgery in patients with PAET. BTX has the advantage of a shorter procedure duration, lower costs, less exposure to general anesthesia and being minimally invasive intervention.

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.

The Efficacy of Dose Increments of Botulinum Toxin A in the Treatment of Childhood Esotropia

Background

Botulinum toxin is known to have a powerful chemodenervation effect, and it is a well-established alternative to incisional surgery for strabismus. This study aims to investigate the efficacy of dose increments of botulinum toxin A (BTA) for the treatment of specific ranges of angle deviation.

Methods

This was a prospective study that included patients presenting with esotropia to Dhahran Eye Specialist Hospital between 2016 and 2020, who were managed by a single surgeon. Botulinum toxin was given in different dosages (2.5, 5, 7.5, 10 international units (IU)) according to the size of deviation (11–19, 20–29, 30–39, and ≥40 prism diopters (PD)), respectively. A successful outcome was defined as deviation ≤10 PD in the last visit (a minimum of 6 months) following a single injection.

Results

A total of 56 patients with esotropia were included. The mean pre-treatment angle of deviation was 38.6 ± 2.5 PD. BTA injection in a dose of 2.5 IU for the 11–19 PD angle of deviation showed the highest rate of successful outcomes (75%). According to the type of esotropia, partially accommodative esotropia showed the best response to the use of dose increments (59%). The incidence of ptosis post-BTA injection was the least (37.5%) with the smallest dose (2.5 IU).

Conclusion

BTA usage in dose increments is safe, efficient, and might be more cost-effective with less incidence of BTA associated complications. Different esotropia diagnoses have different clinical responses. However, larger studies are necessary to better predict the outcome of using dose increments.

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.

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

Botulinum toxin has been used extensively in strabismus management. However, less is published regarding its use in small-angled manifest deviations or decompensating heterophorias, where an alternative to surgery is required. The aim of this review is to look at the use and effectiveness of botulinum toxin in managing small-angled manifest deviations, both constant and intermittent, and decompensating heterophorias. These types of strabismus can prove difficult to manage, as the angle present is often too small for surgery to be advised, but it may still cause a cosmetic or symptom-producing problem. A search of the English speaking literature was undertaken using Medline facilities as well as a limited manual search of non-Medline journals and transactions. A brief overview is provided for mechanisms of action, complications and dose effects, and diagnostic and therapeutic uses of botulinum toxin. The main reported complications are those of ptosis, induced vertical deviation and subconjunctival haemorrhage. The higher the dose, the greater the risk of complications. In small-angle strabismus, botulinum toxin is reported as particularly useful in cases of acquired and acute-onset esotropia in aiding maintenance of binocular vision. It is useful for additional management of surgically under- or over-corrected esotropia, particularly for those with potential for binocular vision. Less effect is reported in primary exotropia versus primary esotropia. It is the management of choice for consecutive exotropia, particularly when patients have had previous multiple surgery and where there is a risk for postoperative diplopia. Botulinum toxin has a specific role in decompensated heterophoria, allowing the visual axes a chance to 'lock on' and subsequently maintain binocular vision. Successful outcomes are reported after 1-2 injections only but the results are best in cases of heterophoria with little near-distance angle disparity.

Ocular motility disturbances after episcleral plaque brachytherapy for uveal melanoma

OBJECTIVE

To evaluate contributions of various factors in the development of strabismus after iodine-125 brachytherapy for uveal melanoma.

METHODS

Twenty consecutive patients who underwent episcleral plaque brachytherapy for uveal melanoma underwent a full orthoptic examination before and after the surgery. Iodine-125 seeds at 5-mCi strengths were used with a mean total dose of 10.400 cGy toward the tumor apex.

RESULTS

Average follow-up time was 25.4 months (range, 14 to 40). At 12 months all tumors showed regression, 9 patients had visual acuity of 20/200 or better, and 4 patients had ambulatory vision. After tumor treatment, 8 patients were orthophoric, 9 patients developed exotropia, 1 patient became hypertropic, 2 patients developed exotropia and hypertropia. Of 2 patients who developed significant diplopia, 1 received 10 U botulinum-toxin A injection (Botox, Allergan, Irvine, CA) for exotropia, and the other was managed with superior rectus advancement and superior oblique tenectomy for surgery-induced iatrogenic Brown's syndrome and slipped superior rectus muscle.

CONCLUSION

Extensive mechanical injury, possible ionizing radiation of the plaques, and low visual acuity may cause strabismus after episcleral plaque brachytherapy. Diplopia and cosmesis could be improved with Botox injection or strabismus surgery.

Quantitative changes in botulinum toxin a treatment over time in patients with essential blepharospasm and idiopathic hemifacial spasm

PURPOSE

To evaluate the quantitative changes in botulinum toxin A (BTA) treatment required over time to achieve relief for 3 to 4 months in patients with essential blepharospasm (EBS) and idiopathic hemifacial spasm (IHFS).

DESIGN

Interventional case series.

METHODS

In this retrospective longitudinal study in an institutional ophthalmologic outpatient clinic, data were retrieved from patient files and a comparison between patients with EBS and IHFS was performed. The patient population consisted of 27 patients, 17 with EBS and 10 with IHFS, who were treated for the first time with BTA injections and were followed up for 4 to 6 consecutive years. All patients initially received 12 or more courses of treatment with a lower dose (<or=20 U) and were then switched to a higher dose (>20 U). The main outcome measures were the shift in the dose-response relationship between the lower and higher doses and were analyzed with respect to four variables: average number of treatments, dosage, duration of therapy, and interval of symptomatic relief.

RESULTS

In the EBS group the mean dose for each patient changed from 16.0 +/- 1.4 U (lower dose) to 24.2 +/- 1.4 U (higher dose). The shift occurred after a mean of 8.8 +/- 2.9 treatments per patient given for a mean of 33.5 +/- 13.3 months. The mean interval of relief was longer with the lower dose than with the higher dose (4.0 +/- 1.4 months vs 3.2 +/- 1.0 months, respectively). In the IHFS group, the mean dose / patient changed from 16.8 +/- 1.2 U to 25.0 +/- 1.8 U, and the switch occurred after a mean of 6.5 +/- 2.3 treatments given over a mean period of 23.8 +/- 6.6 months. The mean duration of treatment with the lower dose was shorter than with the higher dose. The interval of relief was similar for both dose ranges (3.8 +/- 10 months and 4.1 +/- 1.3 months, respectively). The IHFS group switched to the higher dose earlier, by both number and duration of treatments, than the EBS group. Only minor and transient side effects of treatment were observed in both groups.

CONCLUSIONS

Botulinum toxin A is an effective and safe treatment for EBS and IHFS. The dose in our study was increased over time by 50% to achieve 3 to 4 months of symptomatic relief with minimal complications.

Efficacy and complications of dose increments of botulinum toxin-A in the treatment of horizontal comitant strabismus

PURPOSE

To investigate the efficacy and complications associated with dose increments of botulinum toxin-A (BTA) for comitant horizontal strabismus patients.

METHODS

Twenty-five esotropic (ET) and 45 exotropic (XT) patients received 2.5-20 U of BTA injection. Parameters for achieving less than 10 prism dioptres (pd) of horizontal deviation and percentage correction of the pretreatment deviation were assessed for injections of less than 10 U and more than 10 U of BTA. Induced ptosis and vertical deviation were examined within and after 6 months of follow-up.

RESULTS

The mean pretreatment deviations were 38.6 +/- 2.5 pd and 37.6 +/- 1.9 pd for the ET and XT groups, respectively. After receiving 1.6 and 1.5 injections on average, improvement to less than 10 pd at the primary position occurred in 32% of ET and 22% of XT patients; the difference was not statistically significant. The percentage corrections of the ET patients were 41.4 +/- 9.3% and 36.9 +/- 5.6% in those treated with less than 10 U and more than 10 U of BTA respectively; the difference between the two groups was insignificant. For the XT patients the values were 42.1 +/- 7.4% and 28.9 +/- 3.5% respectively, which also were not statistically significantly different. Frequency of induced ptosis was more common in ET than XT patients (p = 0.01) and this difference was more pronounced with increased doses of BTA (7.7% in ET and 5.3% in XT patients with less than 10 U of BTA, and 24.0% in ET and 4.3% in XT patients with more than 10 U of BTA). Ptosis resolved completely within 6 weeks in all cases. Induced vertical deviation with less than 10 U of BTA was encountered in one case of ET (11.1%, 9 pd) and in another case of XT (8.3%, 4 pd), increasing to 60.0% (2-20 pd) and 38.8% (4-16 pd) respectively with more than 10 U of BTA injection. In about a year, induced vertical deviation resolved in approximately 40%, and decreased in 30% of the cases.

CONCLUSION

Increasing the dose of BTA is clinically effective in larger deviations, although statistically indifferent, especially in ET compared with XT. However, an increased dose is accompanied by increased incidence of induced ptosis and vertical deviation. Ptosis is temporary, but vertical deviation may persist for a long time and may present a cosmetic problem for some patients when more than 10 U of BTA is used.

Botulinum treatment of infantile esotropia with abduction nystagmus

PURPOSE

To examine the effect of botulinum toxin type A (BTA) on the final correction of esotropia, A and V patterns, overaction of the oblique muscles, and dissociated vertical deviation (DVD) in infantile esotropia with nystagmus in abduction.

METHODS

This retrospective study examined 54 patients treated with simultaneous bilateral medial injection of BTA. Subjects were divided into two groups: group 1 (first injection <18 months of age) and group 2 (first injection >18 months of age).

RESULTS

Pre-BTA, group 1 patients had an angle of esotropia noticeably higher and fewer A patterns than group 2 patients. Post-BTA, group 2 received significantly fewer injections of BTA than group 1. The magnitude of the A patterns improved. Prior frequency of DVD increased significantly in group 1 (100%): 79% of DVD was decompensated compared with 47% in group 2. Overall success was obtained in 14% and 58% of groups 1 and 2, respectively.

CONCLUSION

We do not support BTA treatment in infantile esotropia with nystagmus in abduction prior to age 18 months. After 18 months, the horizontal results are excellent and neither the incidence nor the degree of previous DVD are decompensated, resulting in high success rates for overall deviation and improving anisotropy in A.

What is the role of botulinum toxin in the treatment of dysthyroid strabismus?

BACKGROUND

Botulinum toxin A has been used in the treatment of dysthyroid strabismus primarily as a temporary measure during the active phase of the disease. We report on our experience with 65 patients.

METHOD

We review the records of 65 patients with dysthyroid strabismus who were treated with botulinum toxin A at Moorfields Eye Hospital between 1984 and 1996.

CONCLUSIONS

Patients with a short duration of relatively mild dysthyroid strabismus have a chance of long-term benefit with botulinum toxin A. There is little use for botulinum toxin A in cases of severe dysthyroid disease.

The long-term use of botulinum toxin for adult strabismus

PURPOSE

To characterize patients choosing repeated botulinum toxin injection as a treatment for their strabismus, and assess their demand for it over time (up to 8 years).

METHOD

Patients who had undergone at least eight injections were identified and their clinical records analyzed for diagnosis, demographic details, and demand for toxin injections with time. To establish any predictive variables, the details for these cases were compared with those of matched controls who had undergone fewer injections. Lastly, a questionnaire was mailed to research patients' views as to the indications and preferences for regular toxin injection as a method of treatment.

RESULTS

Ninety-five patients were identified (34 men, 61 women; median age 37 years), of whom 35 had consecutive exotropia and 16 had secondary exotropia. Other diagnoses represented were residual and primary deviations, restrictive exotropias, and oscillopsias. A trend of fewer injections over the attendance period was seen, and the only complication observed was upper lid ptosis in 1% of injections. Cases exhibited similar demographic composition to matched controls, but were more likely to have consecutive exotropia or secondary esotropia as a diagnosis. Univariate analysis showed evidence (p < 0.001) of an association between the number of previous operations and the odds of being a case. No evidence was found that cases and controls lived at differing distances from our hospital. The questionnaire found that 71% of patients stated appearance as the prime reason for seeking treatment, and 37% stated simplicity of toxin therapy as their reason for reattendance. Twenty-six percent of the patients were disillusioned with the results of previous surgery and preferred toxin therapy as a means of controlling their symptoms.

CONCLUSION

Botulinum toxin injection is an appropriate long-term treatment for some strabismus patients who choose not to undergo further surgery. A trend toward fewer injections with time was observed, and no adverse effects were associated with long-term treatment.