Primary-position hypotropia after anterior transposition of the inferior oblique

Retro-equatorial inferior oblique myopexy for treatment of inferior oblique overaction

AIM

To compare the effectiveness of inferior oblique retroequatorial myopexy and inferior oblique myectomy in correction of inferior oblique overaction (IOOA).

PATIENTS AND METHODS

This was a pilot study study including forty patients with primary IOOA of all grades, with or without primary position horizontal deviations. Patients were randomized to have either IO retroequatorial myopexy, group A, or IO myectomy, group B. Success was defined as elimination of the IOOA at 6 months postoperatively. Secondary outcome measures included residual or recurrent elevation in adduction, development of postoperative hypotropia in adduction, postoperative contralateral IOOA, major intraoperative complications, and reversibility of the procedure.

RESULTS

At 6 months postoperative, the success rate was higher in the myectomy group (76%) than in the myopexy group (58%); however, this difference was not statistically significant (P = 0.1). The incidence of residual IOOA in myopexy group was significantly higher in patients with higher preoperative grades of IOOA (P ˂ 0.001). While this difference was not statistically significant among patients in myectomy group (P = 0.09). Collapse of V-pattern was acheived in nine (69%) patients in myopexy group compared with 8 (57%) in myectomy group with a statistically significant difference (P ≤ 0.001). No patients in myopexy group developed postoperative hypotropia in adduction or postoperative contralateral IOOA, compared with eight (22%) patients of myectomy group (P = 0.002) who developed postoperative hypotropia and two (66.6%) patients with unilateral IOOA who developed contralateral IOOA in myectomy group (P ˂ 0.001). No intraoperative complications were encountered in either group. postoperative.

CONCLUSIONS

Retroequatorial myopexy of the inferior oblique is as effective as inferior oblique myectomy in eliminating lower and moderate grades of primary IOOA; however, it is more effective in collapsing V-pattern associated with IOOA, and is not associated with postoperative hypotropia or contralateral IOOA after unilateral surgery. It can be used as a safe, reversible alternative to myectomy; however, it is not suitable for high grades of IOOA.

Effect of inferior oblique anterior transposition in correcting vertical hyperdeviation in primary position

OBJECTIVE

To evaluate the effect of inferior oblique anterior transposition (IOAT) on improvement of vertical hyperdeviation in primary position.

METHODS

This study was a retrospective review and included 35 eyes of 33 patients (18 males and 15 females). Patients with dissociated vertical deviation were not included in the study. Preoperative and postoperative average follow-up was 11.46 ± 11.73 and 11.43 ± 9.73 months, respectively. The eyes were divided into 5 groups according to the amount of transposition. Inferior oblique muscle was transpositioned 2 mm posterior to the inferior rectus insertion in group 1; 1 mm posterior to the inferior rectus insertion in group 2; parallel to the inferior rectus insertion in group 3; 1 mm anterior to the inferior rectus insertion in group 4; and 2 mm anterior to the inferior rectus insertion in group 5.

RESULTS

The mean preoperative and postoperative vertical hyperdeviation were 16.52 ± 5.54 and 0.97 ± 2.34 prism diopters (PD), respectively. The mean preoperative vertical hyperdeviation in group 1, group 2, group 3, group 4, and group 5 was 11.0 ± 4.24, 12.88 ± 4.26, 16.63 ±3.50, 19.83 ± 2.71, and 25.5 ± 3.00 PD, respectively. Postoperatively, improvement in vertical hyperdeviation in group 1, group 2, group 3, group 4, and group 5 was 11.0 ± 4.24, 11.63 ± 3.20, 15.46 ± 3.19, 18.17 ± 2.23, and 25.5 ± 3.00 PD, respectively. The vertical hyperdeviation had improved 100% in group 1; 90.2% in group 2; 92.9% in group 3; 91.59% in group 4; and 100% in group 5.

CONCLUSION

IOAT surgery planned according to hyperdeviation amount has effective and predictable results in correcting vertical hyperdeviation in primary position.

Treatment of Inferior Oblique Muscle Overaction with Myectomy Or with Anterior Transposition

This paper presents a comparative study of the effectiveness of myectomy and anterior transposition in the treatment of inferior oblique muscle overaction. We operated 160 patients with overaction of the inferior oblique muscle. Eighty patients (148 eyes) were operated by myectomy at the insertion and 80 patients (151 eyes) by anterior transposition of the insertion of the inferior oblique near the temporal side of the insertion of the inferior rectus muscle. Comparison of the two methods, using the chi-squared test, showed that:

1) both surgical procedures were equally effective (χ2=0.26) for correcting overaction of the inferior oblique muscle and V-phenomenon;

2) weakening of the inferior oblique muscle of both eyes was almost always required (in 115 out of 116 cases) in cases with V-phenomenon and often (24 out of 44 cases) in cases of congenital paresis of the superior oblique muscle. We conclude that both procedures are equally effective and equally easy to perform.

Comparative study of unilateral versus bilateral inferior oblique recession/anteriorization in unilateral inferior oblique overaction

PURPOSE

To compare the effect of, and the rate of subsequent development of iatrogenic antielevation syndrome after, unilateral versus bilateral inferior oblique graded recession-anteriorization to treat unilateral inferior oblique overaction.

METHODS

Thirty-four patients with unilateral inferior oblique overaction were included in a randomized prospective study. Patients were equally divided into 2 groups. Group UNI underwent unilateral, group BI bilateral, inferior oblique graded recession-anteriorization. A successful outcome was defined as orthotropia, or within 2 ∆ of a residual hypertropia, in the absence of signs of antielevation syndrome, residual inferior oblique overaction, V-pattern, dissociated vertical deviation, or ocular torticollis.

RESULTS

A successful outcome was achieved in 11 (64.7%) and 13 (76.5%) patients in groups UNI and BI, respectively (p = 0.452). Antielevation syndrome was diagnosed as the cause of surgical failure in 6 (35.3%) and 2 (11.8%) patients, in groups UNI and BI, respectively (p = 0.106). The cause of surgical failure in the other 2 patients in group BI was due to persistence of ocular torticollis and hypertropia in a patient with superior oblique palsy and a residual V-pattern and hypertropia in the other patient.

CONCLUSIONS

The differences between unilateral and bilateral inferior oblique graded recession-anteriorization are insignificant. Unilateral surgery has a higher tendency for the subsequent development of antielevation syndrome. Bilateral surgery may still become complicated by antielevation syndrome, although at a lower rate. In addition, bilateral surgery had a higher rate of undercorrection. Further studies on a larger sample are encouraged.

The effect of anterior transposition of the inferior oblique muscle on eyelid configuration and function

Purpose:

To evaluate the alteration of lower lid configuration and function with anterior transposition surgery of the inferior oblique (IO) muscle.

Patients and Methods:

A prospective clinical trial was conducted on a consecutive series of patients underwent anterior transposition of the IO as a sole operation. All patients received a thorough ophthalmic examination 1 day before and 3 months after surgery. Output parameters were consisted of palpebral fissure, margin reflex distance 1–2, lower lid function, hertel value, and lower lid crease. The differences of the collected data were calculated for statistical significance by using the Wilcoxon test.

Results:

A total of 19 eyes of 16 consecutive patients were included. The median preoperative grade of IO overaction was 3.5 (ranging from 3 to 4), which decreased to 0 (ranging from 0 to 2) postoperatively (P < 0.05). No significant change was observed in all parameters 3 months postoperatively (P > 0.05).

Conclusion:

In this study, no significant effect on lower lid configuration and function was observed following IO anterior transposition in which the disinserted muscle was placed posterior to inferior rectus insertion.

Anterior transposition vs anterior and nasal transposition of inferior oblique muscle in treatment of dissociated vertical deviation associated with inferior oblique overaction

PURPOSE

To compare results of two surgical techniques; anteriorization (ATIO) vs anterior nasalization (ANT) of IO muscle in management of DVD associated with IOOA.

METHODS

Twenty-one patients with DVD associated with IOOA were included in this study. Group A consists of 11 patients who underwent ATIO and group B with 10 patients who underwent anterior transposition of IO to the nasal border of inferior rectus ANT. All patients were followed for at least 6 months postoperatively. The primary outcome variables were changes in DVD in primary position and side gazes, IO action and V pattern.

RESULTS

The average of correction of DVD in primary position, in adduction and in abduction was 10.63 PD, 24.6 PD (P<0.001) and 0.45 PD5 (P>0.05) in ATIO group and 14.6 PD, 25.2 PD and 1.7 PD (P<0.001) in ANT group respectively. Mean IOOA decreased from +2.0±0.7 to +0.18±0.4 in group A (P<0.001) and from +2.5±0.7 to +0.1±0.5 (P<0.001) in group B. Mean V pattern was corrected from 19.18±7.1 PD to 11.18±4.9 PD (P<0.01) in group A and from 17.8±7.9 PD to 6.0±2.49 PD (P<0.001) in group B. In group B, two patients developed hypotropia of 2 and 4 PD and one patient developed consecutive exotropia.

CONCLUSIONS

In DVD associated with IOOA, both surgical techniques are almost similar in alleviating true hypertropia in side gaze, IOOA, and V pattern. ANT gives more statistically significant DVD correction in primary position and in abduction while in adduction; there is no significant difference between both groups. However, ANT may induce hypotropia and consecutive horizontal strabismus.

Z-myotomy of the inferior oblique for small incomitant hypertropias

BACKGROUND

Small hypertropic deviations due to inferior oblique muscle overaction may cause symptomatic diplopia and frustration because incomitant deviations render prism correction unsatisfactory. The several most common surgical options for inferior oblique weakening risk overcorrection of these smaller deviations. In this study we report the results of a "Z-myotomy" of the inferior oblique muscle to correct small incomitant hypertropias due to mildly overacting inferior oblique muscle.

METHODS

The medical records of patients who underwent inferior oblique Z-myotomy at a single center from 2000 to 2005 were retrospectively reviewed. All patients had a mildly overacting inferior oblique (≤+2) and demonstrated fusion. All patients were diplopic, which was the indication for surgery. Pre- and postoperative deviation was measured and ocular motility was assessed.

RESULTS

A total of 38 patients were included. Of these, 24 underwent unilateral inferior oblique Z-myotomy; 5, bilateral Z-myotomy; 5, simultaneous contralateral inferior rectus recession; and 4, simultaneous contralateral inferior oblique recession. In most cases the postoperative measurements demonstrated an almost complete "collapse" of the strabismus pattern. On average, a Z-myotomy procedure required 5-7 minutes to perform. There were no intraoperative complications or deviation overcorrections.

CONCLUSIONS

The inferior oblique Z-myotomy is a straightforward, quick, sutureless procedure. It can serve as an effective alternative weakening procedure for normalization of ductions in cases of minimally overacting inferior oblique muscle with small incomitant hypertropias. The risk for symptomatic overcorrection is very small.

Surgical management of long-standing antielevation syndrome after unilateral anterior transposition of the inferior oblique muscle

PURPOSE

To investigate surgical management of patients with long-standing antielevation syndrome following unilateral anterior transposition of inferior oblique muscle.

METHODS

We present a series of 3 consecutive patients with significant hypotropia several years after unilateral anterior transposition surgery. An approach combining denervation-extirpation of the inferior oblique muscle and subsequent inferior rectus muscle recession and contralateral superior rectus muscle recession was used to manage all 3 patients.

RESULTS

Denervation-extirpation surgery alone or with ipsilateral inferior rectus muscle recession were not enough to improve vertical misalignment in these patients. All 3 patients achieved successful results after denervation-extirpation surgery, ipsilateral inferior rectus muscle recession, and contralateral superior rectus muscle recession.

CONCLUSIONS

In this case series, devervation-extirpation surgery on the inferior oblique muscle, ipsilateral inferior rectus recession, and contralateral superior rectus recession improved vertical misalignment in patients with long-standing antielevation syndrome after unilateral anterior transposition of the inferior oblique.

Asymmetric inferior oblique anterior transposition for incomitant asymmetric dissociated vertical deviation

BACKGROUND

Inferior oblique anterior transposition (IOAT) is indicated in patients with incomitant dissociated vertical deviation (DVD) larger in adduction. In general, bilateral surgery is recommended in patients with DVD unless there is deep monocular amblyopia. The purpose of this study is to evaluate the results of asymmetric IOAT in patients with asymmetric incomitant DVD larger in adduction.

METHODS

Retrospective chart review of the records of all patients with incomitant asymmetric DVD associated with inferior oblique (IO) overaction who underwent asymmetric IO weakening procedure. In all patients, the eye with more DVD in adduction underwent IOAT to the temporal corner of the insertion of the inferior rectus (IR) muscle, and the eye with less DVD underwent IOAT to a position 3-4 mm posterior to the insertion of the IR. No other muscles were operated simultaneously. No patient had previous surgery on any cyclovertical extracular muscle.

RESULTS

Fourteen patients were included. Mean age at surgery was 10.3 ± 8.8 years (range 4-33). Primary position DVD preoperatively was 18 ± 2 PD in the eye with the larger DVD compared to 1.1 ± 1.0 PD postoperatively (p < 0.0001). DVD asymmetry between the lateral gaze with the largest DVD and the lateral gaze with the smallest DVD was 9.8 ± 3.1 PD (range 5-14 PD) preoperatively vs 1.1 ± 1.0 PD (range 0-2 PD), (p < 0.0001). Ten patients had preoperative V-pattern >10 PD (24.7 ± 8.7 PD, range 12-50 PD) preoperatively vs no patients postoperatively (mean V-pattern 4.4 ± 2.0 PD), (p < 0.0001). Postoperative follow up was 1.6 ± 0.7 years (range 1-3 years).

CONCLUSION

In patients with asymmetric incomitant DVD, asymmetric IOAT improves lateral incomitance without increasing the risk of antielevation, limitation in upgaze rotation, or hypertropia, or worsening the DVD in the eye with less deviation preoperatively.

Combined resection and anterior transposition of the inferior oblique muscle for treatment of large primary position hypertropia caused by unilateral superior oblique muscle palsy

PURPOSE

To evaluate the efficacy of combined resection and anterior transposition of the inferior oblique muscle for treatment of unilateral superior oblique muscle palsy with hypertropia from 20(Δ) to 25(Δ) in primary position.

METHODS

The medical records of consecutive patients operated on for unilateral superior oblique muscle palsy and hypertropia from 20(Δ) to 25(Δ) in primary position were retrospectively reviewed. All patients had overaction of the inferior oblique muscle. The inferior oblique muscle was disinserted and 4 mm of its distal end was resected and transposed to the lateral border of the inferior rectus muscle insertion. The prism and alternate cover test was used to measure hypertropia. Surgical results were evaluated at 6 months' follow-up.

RESULTS

A total of 27 patients were included. The mean hypertropia in primary position was 22.6 ± 0.4(Δ) preoperatively, which decreased to 1.4 ± 0.6(Δ) after surgery. None of the patients developed hypotropia in primary position. Mild limitation of elevation was recorded in 1 patient, and 4 patients developed lower eyelid fullness.

CONCLUSIONS

In this patient cohort, combined resection and anterior transposition of the inferior oblique muscle effectively treated unilateral superior oblique muscle palsy with hypertropia from 20(Δ) to 25(Δ) in primary position.

The effect of inferior oblique muscle Z myotomy in patients with inferior oblique overaction

PURPOSE

To investigate the surgical outcomes of inferior oblique muscle Z myotomy in patients with inferior oblique overaction (IOOA).

METHODS

A prospective study was performed in 21 patients (primary IOOA in 13 patients, secondary IOOA in 8 patients) who underwent inferior oblique muscle Z myotomy. Patients with IOOA under the degree of +2 were included. Seventy percent of Z myotomies were performed at 6 mm along the physiological path after identifying the inferior oblique muscle through an inferotemporal fornix incision. A comparison was made before the operation and 3 months postoperatively on the degree of IOOA, vertical deviation, and cyclotorsion.

RESULTS

Simultaneous horizontal rectus surgery was performed with inferior oblique muscle Z myotomy because all patients had combined horizontal deviation. The mean degrees of preoperative and postoperative IOOA were +1.9 ± 0.32 and +0.7 ± 0.67 in the primary IOOA group and +1.83 ± 0.41 and +0.17 ± 0.41 in the secondary IOOA group. Six of 7 patients in the primary IOOA group showed V-pattern strabismus, which was improved in all cases after the operation. In the secondary IOOA group, changes of preoperative and postoperative hypertropia and cyclodeviation were from 7.75 ± 6.64 prism diopters and 8.6 ± 2.31° to 1.2 ± 3.35 prism diopters and 4.7 ± 2.02°, respectively. Inadvertent complete myotomy occurred in 1 patient due to excessive traction by an assistant during the procedure.

CONCLUSION

Inferior oblique muscle Z myotomy was an effective surgical procedure in patients with primary and secondary IOOA under the degree of +2.

Anterior transposition of the inferior oblique muscle in the treatment of unilateral superior oblique palsy

PURPOSE

To determine whether unilateral inferior oblique anterior transposition alone could be an effective procedure for treating superior oblique palsy with inferior oblique overaction.

METHODS

The records of 38 patients who underwent unilateral inferior oblique anterior transposition for unilateral superior oblique palsy with inferior oblique overaction were evaluated. A comprehensive ocular examination including best-corrected visual acuity measurements, ductions, versions, and deviations at near and distance, head tilt test, abnormal head position, dilated fundus examination, and Titmus test was performed prior to and after surgery.

RESULTS

The mean patient age was 29 years, the mean follow-up was 32 months, the mean preoperative hypertropia in primary position was 14.29 ± 7.7 prism diopters (PD), and the mean inferior oblique overaction was 3.63 ± 0.67. Anterior transposition of the inferior oblique muscle was effective across a wide range of preoperative primary position hypertropia (4 to 35 PD) with a mean reduction in postoperative hypertropia of 12 PD. Inferior oblique overaction was reduced in all patients. No patient demonstrated postoperative primary position hypotropia. Surgery improved stereoacuity nearly two units using the Titmus stereoacuity scale.

CONCLUSION

Anterior transposition of the inferior oblique muscle is effective in correcting inferior oblique overaction and primary position hypertropia in the treatment of unilateral superior oblique palsy.

Outcome of unilateral inferior oblique recession

PURPOSE

The aim of this study was to analyze the outcome of unilateral inferior oblique (IO) recession in patients with unilateral or asymmetrical IO overaction in terms of effectiveness, stability, and undesired effects.

METHODS

Fifteen patients with nonparalytic strabismus who underwent unilateral IO recession for unilateral or asymmetric IO overaction and horizontal muscle surgery were included in this study. Nine patients demonstrated asymmetric bilateral IO overaction, whereas 6 had unilateral overaction. All patients underwent IO recession to the Scheie Parks point in one eye, along with conventional horizontal muscle surgery. Clinical outcome assessment included changes in oblique muscle dysfunction in both eyes. Changes in horizontal deviation, V pattern, vertical deviation, and excyclotorsion were also studied.

RESULTS

Satisfactory outcome in terms of oblique muscle function, V pattern, vertical deviation, and cyclodeviation was achieved in all patients with unilateral IO overaction and 7 (77%) patients with bilateral IO overaction. Increased IO overaction in the other eye was noted in 2 patients. Satisfactory outcome in patients with bilateral overaction was related to degree of asymmetry in IO overaction between the 2 eyes.

CONCLUSION

Unilateral IO recession is effective in patients with unilateral IO overaction and selected patients with largely asymmetrical bilateral IO overaction.

Antielevation syndrome after unilateral anteriorization of the inferior oblique muscle

PURPOSE

To report antielevation syndrome with restriction of elevation on abduction in the operated eye and overaction (OA) of the inferior oblique muscle (IO) of the contralateral eye after unilateral IO anteriorization (AT).

METHODS

Medical records were reviewed retrospectively in 8 of 24 patients who underwent unilateral IOAT. Four patients were referred from other hospitals after the same surgery.

RESULTS

Four patients had infantile esotropes. The rest showed accommodative esotropia, superior oblique palsy, exotropia, and consecutive exotropia. The mean amount of hyperdeviation was 16.3 PD (10 approximately 30). The mean restriction of elevation on abduction in the operated eye was -1.6 (-1 approximately -4) and IOOA of the contralateral eye was +2.7 (+2 approximately +3). IOAT of nonoperated eyes in 4 patients, IO weakening procedure of anteriorized eyes in 2 patients, and IO myectomy on an eye with IOAT in 1 patient were performed. Ocular motility was improved after surgery in all patients.

CONCLUSIONS

Unilateral IOAT may result in antielevation syndrome. Therefore bilateral IOAT is recommended to balance antielevation in both eyes. A meticulous caution is needed when performing unilateral IOAT.

Unilateral anterior transposition and resection of the inferior oblique muscle for the treatment of hypertropia

BACKGROUND

Anterior transposition of the inferior oblique muscle generally is restricted to bilateral cases because of reports of postoperative ipsilateral hypotropia or significant limitation of elevation when performed unilaterally. We performed unilateral anterior transposition of the inferior oblique muscle in patients with vertical and horizontal strabismus who were at risk of anterior segment ischemia.

PATIENTS AND METHODS

Six patients underwent unilateral anterior transposition of the inferior oblique muscle in combination with a resection of the inferior oblique muscle. Two patients had lost an inferior rectus muscle in a previous procedure, and four patients had coexistent horizontal and vertical strabismus of various etiologies as well as poor unilateral vision.

RESULTS

All six patients achieved vertical alignment within 10 prism diopters.

CONCLUSIONS

Unilateral anterior transposition of the inferior oblique muscle appears to be a useful procedure in selected patients with vertical strabismus.

Unilateral inferior oblique anterior transposition for dissociated vertical deviation

PURPOSE

This study analyzes the outcomes after unilateral inferior oblique anterior transposition (IOAT) for manifest dissociated vertical deviation (DVD).

METHODS

A retrospective chart review was conducted for all patients who had unilateral or markedly asymmetric DVD, ipsilateral overaction of the inferior oblique muscle, lack of alternating fixation, and underwent unilateral IOAT surgery between March 1997 and March 2001. In each case, the bunched inferior oblique muscle was anteriorly transposed to the lateral edge of the insertion of the inferior rectus muscle. The primary outcome variable was change in DVD. Secondary outcome variables included inferior oblique muscle action, graded from -4 to +4, and vertical deviation in primary gaze.

RESULTS

Ten consecutive patients met the inclusion criteria. Median age at the time of surgery was 14 years (range, 2 to 41 years.) Mean follow-up was 25 months (range, 6 to 60 months). Ipsilateral DVD in primary position decreased from a mean of 20.2 prism diopters (PD) (range, 14 to 33 PD) to 3.7 PD (range, 0 to 9 PD) (t test, P <.001). Nine (90%) of the patients had an excellent postoperative result (residual DVD of 0 to 4 PD) and one (10%) had a good result (5 to 9 PD). Inferior oblique overaction was eliminated in all patients. Mean inferior oblique muscle action decreased from +2.4 to -1.3. Three patients developed a transient or permanent 4 to 5 PD postoperative ipsilateral hypotropia in primary position. Dissociated vertical deviation in the fellow eye did not develop, or if present preoperatively, did not increase.

CONCLUSIONS

Unilateral IOAT is an effective treatment for unilateral or markedly asymmetric DVD in patients with a strong, contralateral fixation preference. This surgery reduces inferior oblique overaction but may cause an ipsilateral hypotropia.

Unilateral anterior transposition of the inferior oblique muscle for correction of hypertropia in primary position

PURPOSE

To evaluate the correction of hypertropia in primary position with unilateral inferior oblique (IO) anterior transposition (IOAT).

METHODS

Ten patients with idiopathic (nonparalytic, restrictive, or dissociated vertical deviation) hypertropia with marked IO overaction, who underwent unilateral IOAT, were prospectively evaluated to observe the correction of the hypertropia in primary position. No previous ocular muscle surgery had been performed. Four patients had esotropia and two had exotropia. In addition to the proposed surgery, horizontal procedures were performed to correct horizontal deviation, but no vertical transposition of horizontal muscles was done. Four patients had hypertropia and IO overaction, without horizontal strabismus, and IOAT was the only procedure performed. The IO muscle was reinserted 1 mm laterally to the lateral extremity of the inferior rectus muscle insertion using only one suture. The statistical analysis was performed by Wilcoxon rank sum test.

RESULTS

The mean absolute correction in primary position was 18.1 prism diopters (PD) (range, 4 to 33), directly proportional to the size of the hypertropia before surgery. Nine of the 10 patients had a residual vertical deviation of </=6 PD. After surgery, 4 patients (40%) presented limited elevation in adduction (-2) in the field of the operated IO, presumably caused by the antielevator effect of the transposed muscle, which did not improve during the follow-up period (range, 2 to 79 months).

CONCLUSION

Unilateral IOAT is an effective technique for correction of large hypertropia associated with marked unilateral IO overaction. Some lower lid curvature deformity and some limitation of elevation were observed in forced upgaze in some patients, but this was of no cosmetic importance.

Anterior transposition of the inferior oblique muscle for treatment of superior oblique palsy

PURPOSE

Weakening of the inferior oblique muscle is the procedure of primary importance in patients with superior oblique palsy, Knapp's Classes I and III. In this study, the effectiveness of anterior transposition of the inferior oblique muscle in treatment of these patients was evaluated.

METHODS

Sixteen patients with superior oblique palsy, Knapp's Classes I and III, underwent anterior transposition of the inferior oblique muscle. The tip of the disinserted muscle was sutured to the sclera, parallel, and adjacent to the lateral border of the inferior rectus muscle insertion. The prism and alternate cover test measurements were made in all cardinal positions of gaze before and 6 months after surgery.

RESULTS

The mean reduction of hyperdeviation was 15 prism diopters (PD) in the primary position, 23.4 PD in adduction, 26.65 PD in elevation and adduction, and 18.63 PD in depression and adduction. There was no hypotropia in the primary position. Mild limitation of upgaze has occurred in 3 of these patients, and mild fullness of the lower lid was developed by 25%. Postoperative hyperdeviation in the primary position was 5 PD or less in 15 out of 16 patients.

CONCLUSIONS

The anterior transposition of the inferior oblique muscle is very effective in eliminating hyperdeviation in patients with superior oblique palsy, Knapp's Classes I and III. Up to 25 PD reduction of hyperdeviation in the primary position can be achieved. If this type of anterior transposition is used, primary position hypotropia or marked limitation of upgaze possibly will not occur.

Costenbader lecture. Anatomy and surgery of the inferior oblique muscle: recent findings

BACKGROUND

Surgery of the inferior oblique muscle (IO) has undergone significant changes in the past 160 years. Many investigators have contributed to our understanding of the action of this muscle and to the surgical options that have developed. This article reviews the history of IO surgery with particular emphasis on the anterior transposition procedure.

METHODS

Anatomic and physiologic studies on the neurofibrovascular bundle of the IO are presented.

RESULTS

The ligamentous structure of the neurofibrovascular bundle of the IO provides the ancillary origin for the posterior temporal fibers of the IO when its insertion is transposed anteriorly.

DISCUSSION

Recent anatomic findings have helped explain the effects of the anterior transposition procedure and allow further development of our surgical armamentarium for vertical strabismus problems. Further nasal transposition of that insertion should reduce or eliminate the incidence of the antielevation syndrome. If transposed far nasally, the IO could convert to an intorter, as well as to an antielevator and tonic depressor.

A prospective evaluation of anterior transposition of the inferior oblique muscle, with and without resection, in the treatment of dissociated vertical deviation

BACKGROUND

Anterior transposition of the inferior oblique muscle (ATIO) has become a popular surgical treatment for dissociated vertical deviation (DVD), particularly in patients with coexisting inferior oblique muscle overaction (IOOA). We wanted to assess whether adding a resection improves the outcome compared with standard anteriorization.

METHODS

We undertook a prospective, randomized evaluation of ATIO, with and without a 7-mm resection, in patients with DVD of at least 5 PD in one eye. We included 51 eyes of 30 patients, 26 eyes treated with the standard ATIO and 25 treated with a 7-mm resection added. We recorded the size of the preoperative and final DVD, grade of the preoperative and final IOOA, rates of reoperation, and complications. Mean follow-up was 15.4 months in the standard group and 25.0 months in the resection group, with a minimum of 4 months for all cases.

RESULTS

The median preoperative and postoperative DVD was 12 PD and 4 PD in the standard group, respectively. This compared with 14 PD and 4 PD, respectively, in the resection group, representing no statistically significant difference in outcome. The presence or absence of IOOA did not influence the result of ATIO for either group. No significant complications of surgery occurred in either group.

CONCLUSIONS

ATIO is an effective treatment for DVD and can be used to treat DVD in patients with or without IOOA, with few adverse effects. Our study revealed no advantage to adding a 7-mm resection to the standard procedure.

Combined resection and anterior transposition of the inferior oblique muscle for asymmetric double dissociated vertical deviation

OBJECTIVE

To evaluate the efficacy of combined monocular resection and bilateral anterior transposition of the inferior oblique (IO) muscle for asymmetric double dissociated vertical deviation (DVD).

DESIGN

Nonrandomized, comparative clinical trial.

PARTICIPANTS

Twelve patients with asymmetric DVD and coexisting unequal IO overaction (IOOA).

INTERVENTION

Six consecutive patients underwent combined graded monocular resection and bilateral anterior transposition of the IO muscle and six consecutive historical control patients underwent equal anteriorization of the IO muscle.

MAIN OUTCOME MEASURES

Between-group comparison of the postoperative vertical deviation and reduction in IOOA.

RESULTS

The mean difference of the asymmetric DVD in the primary position was reduced from 13.3 +/- 4.8 prism diopters (PD) to 2.2 +/- 1.8 PD in the study group (P = 0.001) and from 13.3 +/- 4.0 PD to 10.2 +/- 3.1 PD in the control group (P = 0.003). The difference in improvement between the groups was statistically significant (P = 0.004). The IOOA was significantly reduced in both groups.

CONCLUSIONS

Bilateral IO anteriorization with monocular-graded IO resection should be considered as the treatment of choice in patients with asymmetric DVD with IOOA.

Comparison of inferior oblique muscle weakening by anterior transposition or myectomy: a prospective study of 20 cases

BACKGROUND/AIMS

Among the various weakening techniques of inferior oblique muscle overaction, the most commonly used techniques include myectomy, recession, and anterior transposition. Anterior transposition and myectomy were compared to evaluate the surgical results in inferior oblique overaction.

METHODS

20 children with bilateral +3 overacting inferior oblique muscles underwent a prospective randomised study by which the anterior transposition procedure in one eye was compared with the myectomy procedure in the other eye.

RESULTS

Postoperative follow up averaged 2 years. The success rates in two surgical procedures were 85% for the anterior transposition and 25% for the myectomy (standard of success was based on zero inferior oblique overaction). In only one case did the anterior transposition tend to limit the elevation of the eye in the midline, adduction, and abduction. Anterior transposition produced hypotropia at the primary position in only one case. Most eyes that underwent myectomy (75%) showed apparent residual overaction.

CONCLUSION

The anterior transposition appeared to be more effective in eliminating the overaction of inferior oblique muscle than the myectomy.

Comparison of anterior transposition and recession of the inferior oblique muscle in unilateral superior oblique paresis

PURPOSE

Both anterior transposition and graded recession have been shown to be effective procedures in weakening the inferior oblique muscle. Anterior transposition may work in part by converting the inferior oblique muscle from an elevator to a depressor of the globe. In theory, this would be useful in treating the inferior oblique overaction associated with superior oblique paresis. We compared inferior oblique recession and anterior transposition for the surgical correction of Knapp's class III unilateral superior oblique paresis.

METHODS

Four patients underwent 14 mm recession, and five underwent anterior transposition of the inferior oblique muscle for the hypertropia in superior oblique paresis. Prism cover test measurements were made in all cardinal fields of gaze and were compared before and after operation between the two groups.

RESULTS

The mean preoperative hyperdeviation in the primary position was 12 prism diopters in the recession group and 15 prism diopters in the anterior transposition group. The mean postoperative hyperdeviation was 1 prism diopter in the recession group and 3 prism diopters in the anterior transposition group. Postoperative results in the inferior oblique field of action demonstrated a mean 3 prism diopter hypertropia in the recession group and a 2 prism diopter hypotropia in the anterior transposition group.

CONCLUSIONS

Anterior transposition and graded recession gave similar results in correcting the primary position hyperdeviation in Knapp's class III superior oblique paresis. Both procedures also markedly improved the hyperdeviation in the field of action of the inferior oblique muscle and superior oblique muscle. However, anterior transposition was more likely to result in postoperative hypodeviation in upgaze.

Effect of graded anterior transposition of the inferior oblique muscle on versions and vertical deviation in primary position

INTRODUCTION

There are various methods for weakening the inferior oblique muscle; here we describe the results of a graded anterior transposition.

METHODS

Charts of 21 children (37 eyes) who underwent graded anterior transposition of the inferior oblique muscle were reviewed. Graded anterior transposition consisted of reinsertion of the inferior oblique muscle at various points along the temporal aspect of the inferior rectus muscle; the more severe the overaction, the more anterior the placement of the new insertion. In all cases the new inferior oblique insertion line was oriented parallel to the inferior rectus muscle axis. We analyzed the preoperative to postoperative change in inferior oblique overaction (versions) and vertical alignment in primary position.

RESULTS

Postoperatively, 18 of 21 patients had normal versions, 2 patients had -1 underaction of 1 eye, and 1 patient had +1 overaction of both eyes. Eleven patients (15 eyes) had a preoperative vertical deviation in primary position of 4 PD or more. Three of these patients had unilateral congenital superior oblique palsy and a preoperative hypertropia of 20 PD. They underwent unilateral graded anterior transposition with a mean postoperative vertical change of 18 PD. Three patients had asymmetric primary inferior oblique overaction with true hypertropia, 1 patient had amblyopia and primary inferior oblique overaction, and 4 patients had dissociated vertical deviation associated with inferior oblique overaction. All patients had improvement after surgery, with no significant vertical deviation in primary position.

CONCLUSIONS

Graded anterior transposition of the inferior oblique muscle is effective in normalizing versions and correcting vertical deviations in primary position.

The neurofibrovascular bundle of the inferior oblique muscle as the ancillary origin of that muscle

PURPOSE

To establish that the neurovascular bundle (NVB) of the inferior oblique muscle has ligamentous qualities that enable it to function as an ancillary origin to the muscle, particularly after anterior transposition of its insertion.

METHODS

Fresh cadaveric eyes and eyes of surgical patients were studied. Eighteen orbits were dissected to demonstrate the linear course of the NVB and its adjacent fibrous bands. Intact orbits were analyzed histologically, as were autopsy and surgical specimens, to evaluate the capsule of the NVB and the adjacent fibrous bands. The elastic modulus was measured in NVB specimens and in superior oblique tendons. Six eyes in which recurrent inferior oblique muscle overaction developed after an anterior transposition procedure were surgically explored to determine the structure that was serving as its ancillary origin.

RESULTS

Gross anatomic and microscopic studies showed a linear orientation of the NVB,with adjacent fibrous bands anteriorly joining the inferior oblique and inferior rectus muscle capsules. The NVB showed about 50% fibrocollagenous capsule, with the collagen fibers aligned parallel to the NVB. The elastic modulus was highest (stiffest) in the NVB and lowest in the superior oblique tendon. In patients who had undergone anterior transposition operations, the NVB served as the ancillary origin of the inferior oblique muscle.

CONCLUSION

The name of the NVB should be changed to neurofibrovascular bundle because it has a prominent fibrocollagenous capsule and is encased in fibrous tissue bands anteriorly. The neurofibrovascular bundle has a linear course and is relatively stiff. It binds the midposterior portion of the inferior oblique muscle posteriorly. Its ligamentous qualities enable it to function as an ancillary origin for the inferior oblique muscle.

Results of anterior transposition of the inferior oblique muscle in incomitant dissociated vertical deviation

PURPOSE

Recession with anterior transposition of the inferior oblique muscle has been shown to effectively decrease dissociated vertical deviation in primary position. However, studies to date have not addressed the long-term postoperative results with respect to residual deviation in lateral gaze, development of A-pattern strabismus, and the effect of the procedure on upgaze.

METHODS

Twenty-three eyes in 12 patients were treated with recession with anterior transposition of the inferior oblique muscle for dissociated vertical deviation greater in adduction than in abduction (termed incomitant dissociated vertical deviation) associated with inferior oblique muscle overaction. Before the operation, dissociated vertical deviation was measured in primary position and lateral gaze, oblique muscle dysfunction was graded, and A or V patterns were measured. Similar measurements were made after the operation. All patients have been followed up for a minimum of 4 years after the operation.

RESULTS

Recession with anterior transposition of the inferior oblique muscle effectively eliminated the dissociated vertical deviation in primary position and in adduction. The operation was less effective in reducing small amounts of dissociated vertical deviation in abduction. No significant A patterns developed after the operation. Postoperative inferior oblique muscle function ranged from -1 underaction to +2 overaction, and postoperative upgaze in abduction was normal to mildly deficient.

CONCLUSIONS

Recession with anterior transposition of the inferior oblique muscle results in long-term improvement of incomitant dissociated vertical deviation, with a low incidence of late development of A patterns and upgaze deficiency.

Restriction of elevation in abduction after inferior oblique anteriorization

PURPOSE

Inferior oblique anteriorization is gaining popularity for the treatment of dissociated vertical divergence associated with inferior oblique overaction. This procedure is based on the theory that moving the insertion of the inferior oblique muscle anterior to the equator changes its vector of force from one of elevation to one that opposes elevation. The purpose of this investigation is to describe, investigate the cause, and outline treatment for a complication I observed after inferior oblique anteriorization. This postoperative syndrome consists of a motility pattern that resembles marked residual inferior oblique overaction associated with a Y or V pattern. It is probably caused by a restriction of elevation of the abducting eye causing fixation duress, with a resultant upshoot of the contralateral adducting eye.

METHODS

A retrospective chart review was conducted for all patients on whom I performed bilateral inferior oblique anteriorization for inferior oblique overaction associated with dissociated vertical divergence. Patients in whom this postoperative syndrome developed were compared with those in whom it did not with respect to type and extent of surgery. In addition, cases of patients I treated or examined for this complication but whose inferior oblique anteriorization had been performed by other ophthalmologists were also analyzed.

RESULTS

I performed bilateral inferior oblique anteriorization in 77 patients. In 29 patients the inferior oblique muscles were placed level with the insertions of the inferior rectus muscles, in 31 patients they were placed 1 mm anterior to the insertions of the inferior rectus muscles, and in 17 patients they were placed 2 mm anterior. The postoperative syndrome described here developed in two of the 77 patients; both had the inferior oblique muscles placed 2 mm anterior to the insertions of the inferior rectus muscle. These were also the only two patients in this series in whom the new insertion of the inferior oblique muscle was spread out laterally at the time of anteriorization. I have seen an additional six patients in whom this syndrome developed after undergoing operations by other ophthalmologists. In four, the inferior oblique muscles were placed 2 mm anterior to the insertions of the inferior rectus muscles, and in two they were placed 3 mm anterior. Of the eight patients I have observed with this complication, I reoperated on six. The surgical procedure consisted of denervation or extirpation of both inferior oblique muscles in four patients and conversion to standard recessions of the inferior oblique muscles in two patients. In all six patients,the versions were markedly improved and the Y orV pattern was eliminated after reoperation.

CONCLUSIONS

Anteriorization of the inferior oblique muscles more than 1 mm anterior to the insertions of the inferior rectus muscle may cause a limitation of elevation in abduction, resulting in a Y or V pattern that mimics inferior oblique overaction. This may be more likely to occur if the new insertions of the inferior oblique muscles are spread out laterally at the time of anteriorization.

Results of anterior transposition of the inferior oblique

PURPOSE

We present the results of anterior transposition of the inferior oblique in a series of patients with inferior oblique overaction and dissociated vertical deviation (DVD).

PATIENTS AND METHODS

We performed a retrospective study of 37 procedures on 21 patients who had unilateral or bilateral inferior oblique anterior transpositions. Before surgery, patients had +1 to +3 inferior oblique overaction and +1 (< 10 PD) or +2 (10 PD-20 PD) degree of DVD. The inferior oblique insertion was transposed to between 2 mm posterior to and 2 mm anterior to the temporal border of the inferior rectus insertion. Mean follow-up period was 27 months.

RESULTS

Incidence of inferior oblique overaction of +2 or more was reduced from 84% before surgery to 16% at last postoperative assessments. Some 43% of eyes had no inferior oblique overaction and 86% had an improvement in the degree of inferior oblique overaction. At last assessments, 57% of eyes had no evidence of DVD and 68% of eyes had no evidence of DVD or an improvement in the degree of DVD. No patient who had unilateral anterior transposition developed hypotropia in primary position and there was no evidence of inferior oblique underaction in any patient at last assessment. Three patients requiring repeat inferior oblique surgery are discussed, including one patient who developed a large Y-pattern exotropia after bilateral anterior transposition of the inferior obliques.

CONCLUSIONS

Inferior oblique anterior transposition has a place in the treatment of coexistent inferior oblique overaction and dissociated vertical deviation.

Anterior transposition of the inferior oblique in the treatment of unilateral superior oblique palsy

Anterior transposition of the inferior oblique (ATIO), is an accepted surgical procedure for the treatment of primary inferior oblique overaction and dissociated vertical deviation. Our study was undertaken to see if ATIO could be useful in the treatment of preselected unilateral superior oblique palsy (SOP) patients. Three consecutive patients with unilateral SOP with preoperative primary-position hypertropia averaging 27 delta, Knapp class V, underwent ATIO. The results were excellent and none of these patients developed primary-position hypotropia. Complications of ATIO in our patients consisted of some elevation deficiency, elevation of the lower lid in upgaze, and reduced inferior "scleral show" in the surgically treated eye. We are proposing that ATIO be considered as a beneficial operation in unilateral SOP patients with at least 25 delta of preoperative primary-position hypertropia.

The effect of anterior transposition of the inferior oblique muscle

The effect of anterior transposition of the insertion of the inferior oblique muscle was compared with the results from conventional inferior oblique muscle recession in 50 patients. Even though both groups of patients had a similar degree of overaction preoperatively, postoperative inferior oblique muscle action was weaker (P < .01) and upgaze more limited P < .01) in the anterior transposition group. These data suggest that anterior transposition serves to convert the inferior oblique muscle from an elevator to a depressor on attempted elevation. Because anterior transposition is such a powerful weakening operation, we suggest that it be reserved for patients with moderate to severe inferior oblique muscle overaction. To avoid postoperative hypotropia in upgaze, anterior transposition should be performed in both eyes for bilateral inferior oblique muscle overaction and not unilaterally.

Anterior transposition of the inferior oblique muscle for dissociated vertical deviation

BACKGROUND

Recently, anterior transposition of the inferior oblique muscle was reported to be an effective treatment for dissociated vertical deviation (DVD), but data on long-term stability have not been reported.

METHODS

A retrospective, longitudinal analysis of 17 consecutive patients (22 eyes) with dissociated vertical deviation and inferior oblique overaction who had an anterior transposition of the inferior oblique for significant dissociated vertical deviation and a minimum of 12 months postoperative follow-up was undertaken. The size and degree of control of the dissociated vertical deviation and the degree of inferior oblique overaction were assessed preoperatively, and postoperatively at 1 week, at 4 to 6 months, and when last seen. The frequency of postoperative hypotropia and elevation deficits were noted.

RESULTS

The mean preoperative dissociated vertical deviation measured 13.4 delta, and the mean total vertical deviation measured 16.2 delta in primary position at 6 meters. The mean dissociated vertical deviation at last follow-up measured 6.7 delta, and the mean total vertical deviation was 7 delta. The dissociated vertical deviation remained controlled based on objective evaluation and subjective patient/relative response in 19 of 22 eyes after a mean follow-up of 2 years (range, 1 to 4.9 years). It recurred in one eye by 6 months postoperatively and in 3 eyes at the last examination. The inferior oblique overaction did not recur to a significant extent in any patient. The best results were achieved in eyes with preoperative dissociated vertical deviations less than 15 delta (0 of 11 failures). When the preoperative dissociated vertical deviation measured > 15 delta, 3 of 11 were failures. Postoperative primary position hypotropia was uncommon (1 of 17 patients), whereas 27% of eyes had mild postoperative elevation deficits in abduction and adduction.

CONCLUSION

Anterior transposition of the inferior oblique is an effective treatment for dissociated vertical deviation with inferior oblique overaction but may be less stable in the long term when the preoperative dissociated vertical deviation is in excess of 15 delta.

Anterior tendon displacement of the inferior oblique for DVD

The effect of grading the anteriorization of the posterior portion of the inferior oblique muscle tendon fibers, relative to the insertion of the inferior rectus, was assessed for patients with dissociated vertical deviation (DVD). The placement of these fibers was varied dependent on the degree of preoperative DVD. The results from the graded group were compared to a group of patients with DVD that always received the same amount of anteriorization regardless of the degree of preoperative DVD. The results showed that, in general, anteriorization of the inferior obligue muscle tendon fibers to the level of insertion of the inferior rectus was an effective treatment for DVD. In addition, grading the anteriorization of the posterior portion of the inferior oblique muscle tendon fibers significantly decreased residual postoperative deviation.

Recession and anterior transposition of the inferior oblique for treatment of superior oblique palsy

We evaluated the effectiveness of inferior oblique recession with anterior transposition in treating 12 patients with superior oblique palsy. Mean decreases of hypertropia measured 17 prism diopters in the primary position, 24 prism diopters in adduction, and 21 prism diopters on ipsilateral head tilt. Head tilt and diplopia were uniformly eliminated. No surgical complications were encountered. Postoperative deviations were mild and infrequent. Only one patient demonstrated postoperative underaction of the recessed inferior oblique.