Inferior Oblique Muscle Weakening Procedure Research Articles

Effect of combining inferior oblique muscle weakening procedures with bilateral injection of botulinum toxin to both medial recti on esotropia's surgical correction

To evaluate the effects of combing inferior oblique muscle (IO) weakening procedures with injection of botulinum toxin (BTX) to both medial recti on the primary position horizontal alignment after surgery to correct esotropia.

Surgical outcomes of inferior oblique muscle weakening procedures for eliminating inferior oblique muscle overaction: a prospective randomized study

Purpose The aim of this study was to evaluate the outcomes of weakening surgical procedures for eliminating inferior oblique muscle overaction (IOOA). Patients and methods A prospective randomized interventional study was performed on 20 eyes of 12 patients with IOOA. The eyes were classified randomly into three groups. The first group included six eyes treated with inferior oblique (IO) myotomy. The second group included eight eyes treated with IO myectomy. The third group included six eyes treated with IO muscle recession. The ductions, versions, and degree of IOOA were analyzed in all patients before and after surgery. Patients were included in the study only if they achieved a minimal follow-up period of 3 months. Results Orthotropia was achieved in 13 (65%) eyes: three (15%) eyes in IO myotomy group, five (25%) eyes in IO myectomy group, and five (25%) eyes in IO recession group. One (5%) eye of IO myotomy group showed residual degree of IOOA. Underaction of IO occurred in one (5%) eye of IO myectomy and recurrence occurred in five (25%) eyes of all groups. Conclusion Recession is the most effective procedure to eliminate IOOA, whereas myectomy at insertion is the second most effective procedure and myotomy is the least effective procedure.

Effect of combining inferior oblique muscle weakening procedures with exotropia surgery on the surgical correction of exotropia.

PurposeTo determine whether the inferior oblique (IO) muscle weakening procedure combined with exotropia surgery affects the surgical correction of exotropia.DesignInstitutional, retrospective study.MethodsWe retrospectively reviewed the medical records of 310 patients who had undergone exotropia-correcting surgery combined with IO weakening (group A, 64 patients) or without IO weakening (group B, 246) with a postoperative follow-up of 6 months or more. The main outcome measures were the postoperative mean angle of horizontal deviation, the success rate, and the overcorrection rate. Surgical success was defined as an alignment between 10 prism diopters (PD) of exodeviation and 5 PD of esodeviation.ResultsThe postoperative mean angles of exodeviation, throughout the follow-up period, did not significantly differ between the groups. Although the surgical success rate was higher in group B at postoperative 1 month (p = 0.035), there was no statistical difference between the 2 groups from postoperative 6 months.: The final success rates were 56.3 and 51.6% (p = 0.509). The overcorrection rate was significantly higher in group A at postoperative 1, 6 and 24 months (p = 0.017, p = 0.028, p = 0.030, respectively); however, at the final follow-up, there was no overcorrection in either group.ConclusionThe overcorrection rate was higher in group A until postoperative 2 years, even though the mean angles of exodeviation and the success rates did not significantly differ between the 2 groups. Surgeons should be mindful of overcorrection when planning exotropia surgery combined with the IO weakening procedure.

How often does the contralateral inferior oblique muscle need to be weakened after a unilateral inferior oblique muscle weakening procedure?

Introduction: It has been suggested that if surgery is planned to weaken one inferior oblique muscle, in certain cases, consideration should be given for bilateral surgery as the other inferior oblique will often need correction in the future. Purpose: To determine the frequency of contralateral inferior oblique weakening surgery following a unilateral inferior weakening procedure. Methods: A retrospective analysis of the records of 376 patients, who had unilateral inferior oblique muscle surgery between 1984 and 2005. Results: Two hundred six patients had hypertropia alone with a unilateral inferior oblique muscle overaction and 170 patients had an associated horizontal deviation. Seven percent of all patients (n = 26) required second weakening surgery of the contralateral inferior oblique. The rate for reoperation was higher in patients with esotropia (12.6%) compared with patients with exotropia (5.5%) and only hypertropia (5.3%). The average time interval between the first and second surgeries was 17 months. In six patients (2%) the previously operated muscle had to be reweakened. Discussion: Only 11 of 206 patients with hypertropia that had a weakening procedure of the inferior oblique muscle needed surgery of the contralateral inferior oblique muscle. The need for second surgery was also relatively low in patients with exotropia, and it was slightly higher in patients with esotropia. Conclusions: Single inferior oblique muscle-weakening procedures is effective in the vast majority of patients and the need for weakening the contralateral inferior oblique is low.

Ocular Torsion in Unilateral Superior Oblique Palsy

Purpose: We evaluated the concordance of laterality of the paretic eye and the torsional eye in unilateral superior oblique palsy showing an inferior oblique overaction. Methods: Thirty-nine patients diagnosed as having a unilateral superior oblique palsy were evaluated for visual acuity, refractive manifestation, ocular movement, prism cover test, and fundus photograph. Of these patients, 32 derived from congenital causes and 7 acquired the condition from trauma. An ocular movement exam was performed to check an inferior oblique overaction, and a fundus photograph was used to measure the ocular torsional amount. Inferior oblique myectomy or recession was performed along with horizontal strabismus surgery. Results: Objective extorsion was presented in paretic eyes of 29 patients (74.4%) and nonparetic eyes of 10 patients (25.6%). The congenital superior oblique palsy patients were divided into two groups by the concordance of laterality of paretic eyes and torsional eyes. In the concordance group of 22 patients, the torsional amount was decreased from +17.69°to +7.98°and inferior oblique overaction from +2.27°to +0.25°after an inferior oblique muscle weakening procedure. In the discordance group of 10 patients, torsional amount was decreased from +16.97°to +8.73°and inferior oblique overaction from +2.50°to +0.21°postoperatively. In acquired oblique palsy patients, all patients showed the concordance of laterality, and the torsional amount was decreased from +16.76°to +8.80°and inferior oblique overaction from +2.5°to +0.21°after inferior oblique weakening procedure. Conclusions: We found that the paretic eye and the torsional eye may not coincide in congenital superior oblique palsy but always coincide in acquired oblique palsy after trauma. After an inferior oblique muscle weakening procedure, ocular torsional amount of paretic or sound eye is decreased in every case.

Apparent contralateral inferior oblique muscle overaction after unilateral inferior oblique muscle weakening procedures

Background: Unilateral inferior oblique muscle weakening surgical procedures often lead to the appearance of inferior oblique muscle overaction in the contralateral eye. The purpose of this study was to determine how different types of unilateral inferior oblique muscle procedures affect the apparent function of the inferior oblique muscle in the contralateral eye. Methods: A computer search was performed to locate all patients on the pediatric ophtalmology service at the Wilmer Ophthalmological Institute who underwent a unilateral inferior oblique muscle weakening procedure from 1980 to 1994. Only patients with a diagnosis of primary inferior oblique muscle overaction were included in the study. Results: Fourteen patients met the inclusion criteria. One patient had undergone an anterior transposition of the inferior oblique muscle, seven patients had undergone a 10 mm recession of the inferior oblique muscle, and six patients had undergone a myectomy of the inferior oblique muscle. Before the operation, there was no difference in the inferior oblique muscle function of the contralateral eye among the three groups. However, after the operation apparent inferior oblique muscle overaction developed more frequently and to a greater degree in the contralateral eye among patients in the anterior transposition and 10 mm recession groups than among patients in the myectomy group. Conclusion: Either anterior transposition or 10 mm recession of the inferior oblique muscle may limit elevation in abduction in the eye on which inferior oblique muscle surgery was performed. The limitation of elevation in abduction may create apparent inferior oblique muscle overaction in the contralateral eye.

Treatment of alphabetic "V" syndromes

Described in the early fifties, V phenomenon remains a controversial subject in respect to its etiopathogeny. Several theories have been proposed dealing to specific surgical treatments. According to the "oblique" theory, we have been performing a bilateral inferior oblique muscle weakening procedure alone or combined with horizontal muscle surgery in our patients presenting horizontal squint associated with a "V" phenomenon. Since 1984, among the 103 patients presenting with a "V" phenomenon, we have been able to analyze 55 cases (40 "V" esotropias and 15 "V" exotropias) who underwent 3 different surgical protocols; 1) bilateral inferior oblique (IO) muscles weakening procedure combined with conventional horizontal surgery, 2) bilateral IO weakening procedure combined with posterior fixation of Med. Recti (Faden operation) in esotropias only, or 3) bilateral inferior oblique muscles weakening alone. All groups were comparable in respect with there pre-surgical "V" pattern. No statistical significant difference in reduction of the "V" pattern could be demonstrated in the different treatment protocols. "V" esotropias showed a mean 16.3 delta diopter reduction +/- 2.2 SEM in treatment number 1; 19.8 +/- 2.1 in treatment 2. Reduction was only 10.7 +/- 3.3 in group with third treatment. "V" exotropias reduction were: 15.4 delta diopter +/- 1.6 in the combined surgical procedure compared to 18.3 +/- 4.8 in IO weakening alone. No dose-effect relationship could be clearly demonstrated in measured IO weakening procedure. IO weakening procedure is effective in reducing "V" pattern. This effect is enhanced if associated with an horizontal muscle surgery which reduces the horizontal deviation especially in in V esotropias. We prefer Fink's procedure to simple myotomy since its allows a measurable and reversible IO weakening.

Superior oblique tuck surgery in the management of superior oblique palsies.

Three hundred and twenty-four patients with superior oblique muscle palsies required surgery over a 15-year period. Forty-four patients underwent superior oblique tuck surgery. Fifteen patients had unilateral and six bilateral tucks alone. Seventeen had unilateral tucks and three bilateral tucks in conjunction with other extraocular muscle surgery. Three had unilateral tucks with a contralateral Harada-Ito procedure. The best results were obtained with isolated superior oblique tucks and tucks in conjunction with a contralateral inferior rectus muscle recession or an ipsilateral inferior oblique muscle weakening procedure. The mean vertical correction following isolated, unilateral surgery was 3.6 prism diopters (range, 0 to 11 delta) in primary gaze and 15.3 delta (range, 0 to 40 delta) in the field of maximum deviation. The mean eso correction in downgaze with bilateral superior oblique tucks was 15.2 delta (range, 10 to 21 delta). There was no statistically significant correlation between the size of the tuck and the amount of deviation corrected. Some degree of postoperative Brown syndrome was seen in all patients, but became less marked with time and in no patient was it severe enough to require reversal of the tuck. In only four patients was there a significant lessening of the effect of the procedure with time. The results show that the superior oblique tuck procedure is an effective operation. In patients with unilateral muscle palsies, 64.3% with an abnormal head posture, 37.5% with diplopia, and 100% with both an abnormal head posture and diplopia achieved an excellent result. In patients with bilateral muscle palsies, 50% with an abnormal head posture and 66% with both an abnormal head posture and diplopia achieved an excellent result.