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.     

下斜肌减弱术治疗下斜肌亢进的临床分析

目的探讨下斜肌减弱手术不同方式治疗下斜肌亢进和V征的临床效果。方法下斜肌亢进122例160眼,包括原发下斜肌亢进20例37眼及继发下斜肌亢进102例123眼,采用不同手术方式,对其手术效果进行比较。结果122例中术前82例有代偿头位(67.21%)者,术后82例中代偿头位消失50例,好转28例,无效4例。下斜肌减弱术的手术方式:断腱术6眼;部分切除24眼;后徙80眼;前转位50眼。术前下斜肌亢进程度 1,21眼; 2,91眼; 3,42眼; 4,6眼;术后残留下斜肌 1,3眼;其余均得到矫正。术前V型斜视48例,术后V征消失38例,好转10例。单纯下斜肌减弱矫正原在位垂直斜度≤15△。结论下斜肌部分切除、后徙及前转位术矫正下斜肌亢进及V征同样安全有效。     

Combined bilateral superior rectus muscle recession and inferior oblique muscle weakening for dissociated vertical deviation.

PURPOSE: Dissociated vertical deviation (DVD) is a common disorder that is often difficult to treat satisfactorily with extraocular muscle surgery. Weakening both elevators in a single eye is uncommonly performed because of possible severe upgaze deficiency or chin-up head posture postoperatively. METHODS: A retrospective review of medical records was performed that yielded 14 patients who had undergone bilateral superior rectus muscle recessions (mean 8.1 mm, range 5-10 mm) and bilateral inferior oblique muscle recession, myectomy, or anterior transposition in the treatment of DVD. Three additional patients with asymmetric inferior oblique muscle overaction or true hypertropia in primary gaze position were identified who had bilateral superior rectus muscle recessions combined with unilateral inferior oblique muscle weakening. RESULTS: Mild-to-moderate elevation deficiencies were common postoperatively but never exceeded -2 up-gaze limitation (scale 0 to -4) except in the immediate postoperative period and were not associated with persistent chin-up head posturing. Cosmetically objectionable upper eyelid retraction occurred in one patient after re-recession of a superior rectus muscle but before inferior oblique muscle surgery. Only three patients undergoing four vertical muscle surgeries had residual DVD >10 PD in primary gaze position, and none exhibited manifest dissociated strabismus warranting further treatment. CONCLUSION: Bilateral superior rectus muscle recession of up to 10 mm combined with inferior oblique muscle weakening appears to be a safe surgical approach in the management of patients with large angle or recurrent DVD. Our data further suggest that simultaneous four vertical muscle surgery may be preferred in some patients to weakening the superior rectus or inferior oblique muscles alone.     

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.     

下斜肌后徙转位术对眼球运动的影响

目的观察下斜肌后徙转位术对眼球运动的影响。方法顺序选择手术后系统观察≥3年的下斜肌后徙转位和后徙手术两组病例,比较眼球运动状况,并观察前者原在位眼位。结果（1）下斜肌后徙转位组原在位均未出现下斜视,14例单眼手术病例有上转受限,以颞上方为著,6例双眼手术病例无明显上转受限。（2）下斜肌后徙转位组手术后远期（≥3年）下斜肌运动程度、眼球上转程度均明显低于下斜肌后徙组,P〈0.001。（3）下斜肌后徙转位组术后远期下斜肌运动程度、眼球上转程度均低于近期（1周～1个月）,P〈0.05,而术后中期（3～6个月）与远期下斜肌运动程度、眼球上转程度之间无明显差异,P〉0.05。结论下斜肌后徙转位术导致术后眼球运动出现非共同性变化,主要是上转受限,对侧眼上转亢进。     

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.     

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.     

Marginal myotomy of the minimally overacting inferior oblique muscle in asymmetric bilateral superior oblique palsies.

PURPOSE: We report the surgical results of marginal myotomy of a minimally overacting inferior oblique muscle in conjunction with traditional recession or myectomy of the greater overacting inferior oblique muscle in 10 patients with asymmetric bilateral superior oblique palsies and asymmetric inferior oblique overaction. METHODS: Ten consecutive patients with bilateral superior oblique palsies had a hypertropia in primary position (5-28 PD) and unequal inferior oblique overaction (0 to +2 in the lesser overacting inferior oblique muscle, +2 to +4 in the greater overacting inferior oblique muscle). Reversal of the hypertropia was noted in ipsilateral oblique upgaze. All patients underwent a recession or myectomy of the greater overacting inferior oblique muscle and a marginal myotomy of the lesser overacting inferior oblique muscle. RESULTS: Seven patients had no vertical deviation in primary position, 2 patients had a residual hypertropia of 2 to 3 PD, and 1 patient had a residual hypertropia of 8 PD. The abnormal head position present preoperatively in 8 patients was eliminated or greatly improved after surgery. Postoperatively all but 1 inferior oblique overaction was graded as 0 to trace. Mean follow-up time was 19 months (range, 1.5-68 months). CONCLUSIONS: In bilateral superior oblique palsies with asymmetric inferior oblique overaction, a mildly overacting inferior oblique muscle can be corrected by marginal myotomy, combined with a recession or myectomy of the greater overacting inferior oblique muscle. This procedure can reduce or eliminate the hypertropia in primary position while minimizing the possibility of residual inferior oblique overaction.     

Inferior oblique muscle fixation to the orbital wall: a profound weakening procedure.

INTRODUCTION: Recurrent or persistent inferior oblique overaction may occur after inferior oblique (IO) recession or anterior transposition. IO nasal and temporal myectomy and anterior-nasal transposition may result in undesirable IO palsy, exotropia, incyclotorsion, or limitation of elevation. Previous studies have shown that a rectus extraocular muscle may be profoundly weakened if the muscle insertion is reattached to adjacent orbital periosteum. We describe a reversible profound weakening surgical procedure of the IO muscle. METHODS: A total of 10 consecutive subjects with V-pattern strabismus and/or IO overaction underwent IO orbital fixation procedure by attaching its insertion to the periosteum of the lateral orbital wall. One subject was not included because short follow-up. Five subjects with persistent IO overaction after IO anterior transposition underwent bilateral IO orbital wall fixation. Four subjects with no previous IO surgery underwent unilateral IO orbital wall fixation; 3 of these 4 subjects had superior oblique palsy with a large vertical deviation in primary position and 1 had a V pattern with asymmetric IO overaction. RESULTS: V pattern significantly improved from 22(Delta) preoperatively to 7(Delta) postoperatively (p = 0.002). IO overaction improved from 2.5 (range, + 1.5 to + 4) to 0.1 (range, -2 to +3) postoperatively (p < 0.001). Six of 9 subjects had no residual overelevation in adduction postoperatively. Unilateral IO orbital fixation corrected 7(Delta) of vertical deviation in the primary position and 23(Delta) in adduction. Mean postoperative follow-up was 5 months. CONCLUSIONS: IO orbital fixation has a profound weakening effect on the IO muscle. Advantages of this procedure include reversibility and that it can be converted into another form of weakening procedure, if required.     

“Inverted Brown pattern”: A tight inferior oblique muscle masquerading as a superior oblique muscle underaction—clinical characteristics and surgical management

PURPOSE: To characterize, and evaluate the surgical management of, patients with unilateral deficiency of depression in adduction, suggesting superior oblique muscle underaction, without significant ipsilateral inferior oblique muscle overaction. METHODS: Such patients were identified who also had received either ipsilateral inferior oblique (IO) muscle weakening or contralateral inferior rectus muscle recession. Their histories, motility patterns, intraoperative findings, types of strabismus surgery, and postoperative results were analyzed. RESULTS: Twelve patients were identified with unilateral deficiency of depression in adduction, with no or minimal ipsilateral IO muscle overaction. Three of these patients (25%) had previously had surgery for Brown syndrome. Four (33%) had prior orbital floor trauma. On exaggerated forced duction testing recorded for nine patients, a tight IO muscle was recorded in 78%, with no laxity of the superior oblique tendon. Four patients (33%) underwent contralateral inferior rectus muscle recession, but in all four the deficiency of depression in adduction recurred. The other eight (67%) had an IO muscle weakening procedure and achieved overall improvement of ocular alignment. Nine subsequent patients with a similar pattern of misalignment were each managed with an IO weakening procedure, with good results. CONCLUSIONS: This motility pattern, which we are calling an "inverted Brown pattern," is caused by a tight or inelastic IO muscle. In such cases, IO muscle weakening yields better results than contralateral inferior rectus muscle recession, even though there is no significant IO muscle overaction preoperatively.     

Myectomy versus anterior transposition for inferior oblique overaction

BACKGROUND: Inferior oblique overaction can be either secondary (as a sequela of ipsilateral superior oblique palsy) or primary (commonly associated with horizontal strabismus). Superior oblique underaction often coexists with both primary and secondary inferior oblique overaction. This retrospective case series compares the efficacy of inferior oblique myectomy versus anterior transposition in improving inferior oblique overaction and superior oblique underaction in eyes with either primary or secondary inferior oblique overaction. METHODS: One hundred twenty eyes of 81 patients were included in this retrospective case series, of which 20 had anterior transposition of the inferior oblique and 100 eyes underwent myectomy. Inferior oblique myectomy was compared with inferior oblique anterior transposition in improving inferior oblique overaction and superior oblique underaction in each diagnostic subgroup. Postoperative outcome was qualitatively and quantitatively assessed. Fisher's exact test was used to compare the outcomes. The quantitative improvement of function in terms of inferior oblique overaction and superior oblique underaction was analyzed by regression analysis. RESULTS: When postoperative inferior oblique overaction was considered, there was no statistically significant difference between myectomy and anterior transposition in both primary and secondary inferior oblique overaction. Myectomy was superior to anterior transposition in improving superior oblique underaction in both primary inferior oblique overaction (OR = 0.14; 95% CI, 0.015-1.45; p = 0.056) and secondary inferior oblique overaction (OR = 0; 95% CI, 0-0.027; p < 0.001). The quantitative improvement of function showed a significant difference between procedures for superior oblique underaction (t-test; p = 0.005; 95% CI, 0.25-1.3) but not inferior oblique overaction (t-test; p = 0.8; 95% CI, -0.67-0.54). CONCLUSIONS: This study demonstrates both inferior oblique myectomy and inferior oblique anterior transposition to be effective in correcting primary and secondary inferior oblique overaction. Myectomy is more effective in improving superior oblique underaction associated with both primary and secondary inferior oblique overaction. On this basis, we feel that inferior oblique myectomy has some advantage over anterior transposition in treating combined inferior oblique overaction and superior oblique underaction and can be considered the procedure of choice.     

三种下斜肌转位术治疗分离性垂直斜视疗效观察

目的观察三种下斜肌转位术治疗分离性垂直斜视的手术疗效,探讨治疗DVD的最佳手术方法。方法伴有下斜肌功能亢进的DVD患者75例,根据手术方式分为3组:单纯下斜肌转位术组、下斜肌截除联合转位术组、下斜肌截除联合前徙并转位术组。观察3组术后1个月、3个月及6个月的眼位、下斜肌运动、代偿头位及并发症情况。结果 3组患者术后下斜肌亢进均消失;代偿头位均不同程度改善;单纯下斜肌转位术组和下斜肌截除联合转位术组术后效果良好者23例(92%)、下斜肌截除联合前徙并转位术组术后效果良好者24例(96%),3组间疗效无明显差异,P<0.05。单纯下斜肌转位术无明显的睑裂变化及上转受限,而联合截除术式有少部分患者出现睑裂变小和眼球上转受限。结论单纯下斜肌转位术可矫正15△~25△的垂直斜视,且术后眼球上转受限和睑裂变化也不明显,是伴有下斜肌功能亢进DVD的首选方法。     

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.     

Antielevation syndrome after bilateral anterior transposition of the inferior oblique muscles: Incidence and prevention

BACKGROUND: Unilateral and bilateral anterior transpositions of the inferior oblique muscle (ATIOs) for primary inferior oblique (IO) muscle overaction may produce apparent new or recurrent overaction of the contralateral IO muscle. This effect has been termed "antielevating" and can produce overaction of the contralateral elevators in adduction that mimics recurrent or new overaction of the IO muscle of the other eye. This phenomenon may be termed the antielevation syndrome (AES). Kushner has hypothesized that this complication of the ATIO is produced primarily by the posterior fibers of the IO muscle. The purpose of this study is to correlate the frequency of this syndrome in a large series of patients with the mm of lateral displacement (spreading) of the IO muscle reattachment site. METHODS: There was a combination of 123 patients who received ATIO from Mims and 77 patients who received ATIO from Kushner. ATIO was performed according to a previously published technique. RESULTS: All 16 patients (14 from Mims and 2 from Kushner) with AES had received bilateral anterior transposition of the posterior fibers of the IO muscle to at least 2 mm anterior to the lateral end of the inferior rectus (IR) muscle with spreading laterally 3 to 5 mm. Among children who had the posterior fibers of their IO muscles placed 2 to 4 mm anterior to a line drawn laterally from the insertion of the IR muscle, the incidence of AES was significantly larger with more spreading out of the new IO muscle insertion. CONCLUSIONS: AES may be prevented by attaching the posterior fibers of the IO muscle no more than 2 mm lateral to the IR muscle insertion site. This complication responds to bilateral nasal IO muscle myectomy in many cases.     

下斜肌前置移位治疗伴有下斜肌亢进的分离性垂直偏斜

目的:观察下斜肌前置移位治疗伴有下斜肌亢进的分离性垂直偏斜(dissociated vertical deviation,DVD)。方法:下斜肌前置移位于下直肌附着点颞侧前2mm或下直肌附着点颞侧成一直线处,同时矫正水平斜视。结果:患者8例11眼中,术前6眼DVD程度是1+,术后DVD消失;术前3眼DVD程度是2+,术后2眼垂直斜视消失,1眼DVD程度为1+;术前2眼DVD程度是3+,术后1眼DVD程度为1+,1眼为2+。所有患者下斜肌均不亢进。结论:下斜肌前置移位是治疗伴有下斜肌亢进的DVD的有效方式,无明显副作用。     

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.     

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.     

Unilateral inferior oblique muscle myectomy and recession in the treatment of inferior oblique muscle overaction: a longitudinal study

BACKGROUND: The comparable long-term outcomes of inferior oblique muscle myectomy and recession for the treatment of superior oblique underaction (in primary position and straight right and left gaze) have not been well documented in the literature. The purpose of this study was to compare longitudinally these two procedures in a similar, patient population with binocular single vision, when both operations were performed by the same surgeon, with a minimum follow-up period of 12 months. METHODS: A total of 24 patients who randomly underwent either a unilateral myectomy (at the temporal border of the inferior rectus muscle) or a standard recession for inferior oblique muscle overaction associated with long-standing superior oblique underaction were evaluated preoperatively at 2 weeks, 4 months, and 12 months postoperatively by the same orthoptist. RESULTS: A total of 23 patients met the study criteria, (12 myectomies and 11 recessions). All but one patient had demonstrable binocular single vision. The average preoperative hyperdeviation in contralateral gaze was 26.5 prism dioptres (Delta) in the myectomies and 20 Delta in the recessions. This was reduced at 12 months postoperatively to 1.75 Delta in the myectomies and to 3 Delta in the recessions. Both procedures were largely self-grading, so that the larger the preoperative hyperdeviation, the greater the effect of surgery. CONCLUSIONS: Single inferior oblique muscle-weakening procedures were effective in the vast majority of patients, even when the preoperative primary position hyperdeviation was 15 Delta or more. An improvement occurred in both groups immediately after surgery and in many throughout the follow-up period represented by a continuing drift towards orthotropia, but there was a recurrence of the hyperdeviation in some of the recession patients.     

Reexploration and inferior oblique myectomy temporal to the inferior rectus to treat persistent inferior oblique overaction.

PURPOSE: Persistent symptomatic inferior oblique (IO) muscle overaction (IOOA) after IO muscle weakening surgery is a common problem. We describe the results of reexploration and myectomy of the IO muscle using a standard inferotemporal approach to treat this clinical entity. METHODS: A retrospective noncomparative consecutive series of patients referred for treatment of persistent IOOA. The following preoperative and postoperative measurements were recorded in each case: (1) the ductions and versions of the overacting IO muscle and its antagonist superior oblique (SO) muscle; and (2) alternate prism cover test, using loose prisms at 6 m, in primary position and right- and leftgaze. The preoperative and longer term postoperative findings were compared. RESULTS: Eight patients were identified. Three had previously undergone a standard IO myectomy, and five had undergone a standard IO muscle recession. The median period of postoperative follow-up was 12 months (range, 7 months to 2 years). The IOOA was eliminated in three patients and a reduction of IOOA of at least 1 unit was achieved in all patients. Seven patients showed improvement of their SO muscle underaction on versions, postoperatively. All patients achieved a marked improvement in their alignment across the three standard horizontal positions of gaze. The mean vertical deviations pre- and postoperatively was 23(Delta) versus 7(Delta) in contralateral gaze, 17(Delta) versus 4(Delta) in primary gaze, and 7(Delta) versus 1(Delta) in ipsilateral gaze. CONCLUSIONS: Reexploration and myectomy of the IO muscle near to the temporal border of the inferior rectus muscle is a reliable and effective way of treating persistent IOOA.     

先天性上斜肌麻痹的手术治疗

目的探讨先天性上斜肌麻痹的各种手术方法与疗效及适应症。方法回顾性分析112例先天性上斜肌麻痹患者分别行患眼下斜肌断腱、下斜肌部分切除、下斜肌后徙转位、下斜肌后徙转位联合健眼下直肌后徙术的术后效果。结果术后平均随访22月（7～36月）,下斜肌断腱术22例,术后满意率86.36%,下斜肌部分切除术16例,术后满意率87.5%,两者治疗效果相当,无明显统计学差异;下斜肌后徙转位54例,术后满意率88.89%;下斜肌后徙转位联合健眼下直肌后徙术20例,术后满意率80%。结论先天性上斜肌麻痹患者应根据术前垂直斜视度的大小选用不同的手术治疗方法,且应该早期治疗。下斜肌断腱和下斜肌部分切除术治疗效果相当,适用于矫正垂直斜视度〈15~△者;下斜肌后徙转位适用于矫正垂直斜视度15~△～25~△者;下斜肌后徙转位联合健眼下直肌后徙术适用于矫正垂直斜视度〉25~△者。