V-pattern Strabismus Research Articles

Comparison of ophthalmic outcomes for children with unilateral coronal synostosis treated with two distinctive craniofacial repairs

Unilateral coronal synostosis (UCS) is associated with the development of V-pattern strabismus, aniso-astigmatism, and amblyopia. One early study reported a trend towards better ophthalmic outcomes in children treated with endoscopic strip craniectomy (ESC) rather than fronto-orbital advancement (FOA). This study provides longer term follow-up to assess validity of the original report.

Insertion Slanting Strabismus Surgical Procedures

Insertion slanting recessions or biased resections have been reported to be useful for treating A- and V-pattern strabismus, convergence insufficiency, and convergence excess esotropia. Paradoxically, good results have been reported with methods that are opposite in nature. For example, some researchers would recess the medial rectus muscles and slant the superior pole of each muscle back farther than the inferior pole (Simonsz/von Graefe method) for a V-pattern esotropia, and others would slant the inferior poles back farther (Bietti method). The Simonsz/von Graefe method seems to be based on sound concepts of oculomotor mechanics. The Bietti method has been justified based on a misquoting and misinterpretation of previous work by Alan Scott, MD. Probably neither method contributes substantially to the outcome of strabismus surgery because sarcomere remodeling should rapidly negate the effect of the slanting. Most likely it is the recession or resection itself that affects the outcome.

Effect of vertical transposition of the medial rectus muscle on primary position alignment in infantile esotropia with A- or V-pattern strabismus

To determine the effect of vertical displacement of muscle insertions on the surgical dose-response relationship in patients undergoing bilateral medial rectus recessions. Retrospective chart review of patients undergoing bilateral medial rectus recessions for correction of congenital esotropia with or without vertical displacement for A or V patterns. Patients were clustered into A pattern, V pattern, and "simple" (no pattern) groups. Strabismus angle at distance and near before and after surgery was recorded. Surgical dose-response relationships (in prism diopters/mm) were determined at the 6-month follow-up visit and compared. A total of 55 patients (28 male and 27 female patients; mean age, 6.9 years; range, 2-17 years) were included. Of these, 28 had either A pattern (18) or V pattern (10), and 27 were in the simple group. Mean preoperative angle of deviation was 34Δ at distance and 40Δ at near. The surgical dose-response relationship was significantly greater (at both distance and near) in the A pattern group (2.43Δ/mm, distance [p=0.005]; 2.76Δ/mm, near [p=0.04]) than in the simple group (1.56Δ/mm, distance; 2.03Δ/mm, near). The surgical response in the V pattern group (1.96Δ/mm, distance [p=0.34]; 2.03Δ/mm, near [p=0.94]) was not significantly different from the simple group. Upward displacement of the medial rectus muscles increased the surgical dose/response relationship in patients with A-pattern esotropia. A similar effect was not observed with downward displacement in patients with V-pattern strabismus. Surgeons should be aware of this enhanced response when planning surgery for A-pattern esotropia.

Superior Oblique Tucks for Apparent Inferior Oblique Overaction and V-pattern Strabismus Associated with Craniosynostosis

Introduction: Apparent inferior oblique overaction and apparent superior oblique underaction are common in strabismus associated with craniosynostosis, and in many cases are likely due to excyclotorsion of the globes, with the rectus muscles acting with oblique vectors. We present a patient with craniosynostosis who underwent bilateral superior oblique tucks to specifically address the excyclotorsion of the globes.Methods: A 16-year-old male with Saethre-Chotzen syndrome presented with apparent bilateral inferior oblique overaction and apparent bilateral superior oblique underaction. He had 30 prism diopter (PD) esotropia and 5 PD left hypertropia by simultaneous prism and cover test (SPCT) at distance and near fixation. Fundus exam revealed marked excyclotorsion of both globes. The superior oblique tendons were tucked 10 mm bilaterally, using a 6-0 mersilene suture and the medial rectus muscles were recessed 5.5 mm on an adjustable suture with a 10-mm inferior displacement. Surgical results were reviewed at 6 weeks and 2 years postoperatively.Results: At 6 weeks and 2 years postoperatively, apparent inferior oblique overaction, apparent superior oblique underaction, and V-pattern esotropia were markedly improved. At 2 years, SPCT measurements were 8 PD esotropia in primary position at distance and 4 PD esotropia and 3 PD left dissociated vertical deviation at near.Conclusions: Bilateral superior oblique tucks are useful in addressing the excyclotorsion that leads to apparent inferior oblique overaction and V-pattern strabismus associated with craniosynostosis.

The Effect of Inferior Oblique Muscle Z Myotomy in Patients with Inferior Oblique Overaction

To investigate the surgical outcomes of inferior oblique muscle Z myotomy in patients with inferior oblique overaction (IOOA). 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. 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. Inferior oblique muscle Z myotomy was an effective surgical procedure in patients with primary and secondary IOOA under the degree of +2.

Effects of vertical offsets of the horizontal rectus muscles in V-pattern exotropia without oblique dysfunction

To investigate the effects of vertical offsets of the horizontal rectus muscle in V-pattern exotropia without oblique dysfunction. A computerized patient database was searched for patients treated with full tendon offsets for V-pattern strabismus from 2002 to 2007. Patients with clinically significant inferior oblique overaction were excluded. Surgery included upward transposition of lateral rectus muscles and/or downward transposition of medial rectus muscles. Medical records were retrospectively analyzed for alignment in the primary position, 30 degrees upgaze, and 30 degrees downgaze before and 3 months after surgery. The main outcome measure was the change in V pattern after surgery. The search identified 11 patients who met inclusion criteria. Of these, 6 underwent bilateral lateral rectus recessions, 1 had 3-muscle surgery, and 4 had monocular recession-resection surgery. The preoperative V-pattern (horizontal) deviation between upgaze and downgaze was 22.2(Delta)+/-5.0(Delta). Postoperative deviation at 3 months was 3.5(Delta)+/-3.9(Delta), a decrease of 18.9(Delta)+/-7.5(Delta). Postoperatively, no patient had an A-pattern deviation or subjective torsional disturbance. The amount of V-pattern correction was closely correlated with the size of the preoperative V pattern (r=0.84). In patients with V-pattern exotropia without inferior oblique dysfunction, vertical offsets of the horizontal rectus muscles effectively corrected the pattern deviation. The amount of correction was closely correlated with the size of the preoperative V pattern.

Treatment of unilateral coronal synostosis by endoscopic strip craniectomy or fronto-orbital advancement: Ophthalmologic findings

Unilateral coronal synostosis results in ipsilateral retrusion of the forehead and superior orbital rim, shortening the elevation of the orbital roof and contralateral frontal bossing and orbital roof depression. This craniosynostosis is associated with the development of V-pattern strabismus and aniso-astigmatism. Since 2004 endoscopic strip craniectomy performed in patients by 3 months of age has been offered as an alternative to fronto-orbital advancement at 9 to 11 months of age. We compare the incidence and severity of V-pattern strabismus and aniso-astigmatism in children treated by these 2 procedures. A retrospective review identified 37 children with unilateral coronal synostosis treated with either fronto-orbital advancement or endoscopic strip craniectomy. Incidence and severity of V-pattern strabismus, fundus excyclotorsion, and aniso-astigmatism was recorded for an "early" examination (between 2 and 14 months of age) and a "late" examination (between 14 and 45 months of age). Early examination revealed no statistical difference in severity of V-pattern strabismus or aniso-astigmatism between the 2 groups. At late examination there was a trend toward greater severity of V-pattern strabismus, an increase in excyclotorsion, and a statistically significant increase in the standard deviation of aniso-astigmatism in the cohort of children treated by fronto-orbital advancement. Children with unilateral coronal synostosis treated by early endoscopic strip craniectomy may develop less severe V-pattern strabismus, excyclotorsion, and range of aniso-astigmatism than those treated by later fronto-orbital advancement. This is an early, retrospective, nonrandomized study with a short follow-up period; longer follow-up is necessary to confirm these results.

Hang-back recession of inferior oblique muscle in V-pattern strabismus with inferior oblique overaction

Although hang-back recession has widely been used as a weakening procedure on extraocular muscles, its effectiveness has mostly been studied for rectus muscles. We report a surgical technique for recessing the inferior oblique muscle and evaluate its effectiveness in V-pattern strabismus with inferior oblique overaction (IOOA). Fifteen patients with V-pattern strabismus and IOOA, 7 with V exotropia, and 8 with V esotropia underwent hang-back recession of inferior oblique muscle in addition to horizontal muscle surgery when required. The surgical technique consisted of free suspension of one or both inferior oblique muscles 10 mm along their physiological path using 6-0 polyglactin 910 sutures bridging the cut ends of muscle. The mean preoperative V pattern in the V-exotropia group was 22(Delta) +/- 6(Delta) and 25(Delta) +/- 7(Delta) in V-esotropia group. The mean correction of V pattern after a mean follow-up period of 8 +/- 1 months was 19(Delta) +/- 2(Delta) for the V-exotropia group and 22(Delta) +/- 7(Delta) months for the V-esotropia group. Mean correction of IOOA in the V-exotropia group was 18(Delta) +/- 5(Delta); in the V-esotropia group, mean correction was 20(Delta) +/- 6(Delta) in the right eye and 18(Delta) +/- 2(Delta) in the left eye. Hang-back recession of inferior oblique is another surgical procedure for correction of both V pattern and IOOA in V-pattern strabismus.

Hang-back recession of inferior oblique in V-pattern strabismus: A novel surgical technique

Hang-back recession of inferior oblique in V-pattern strabismus: A novel surgical technique

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

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. 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. 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. 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.

Anterior transposition compared to graded recession of the inferior oblique muscle for V-pattern strabismus

objective To compare the efficacy of anterior transposition (AT) and graded recession (GR) in the treatment of V- pattern strabismus caused by overaction of the inferior oblique muscle. methods The charts of surgically treated cases of V-pattern strabismus were analyzed retrospectively and the patients classified as AT or GR. Age, initial horizontal deviation, initial V-pattern and the amount of V-pattern correction were compared between the two groups. results There was no significant difference in age (p = 0.066), initial horizontal deviation (p = 0.59), initial V-pattern (p = 0.15) or the amount of V-pattern correction (p = 0.78) between the two groups. conclusion AT is at least as effective as GR in the treatment of V-pattern strabismus caused by overaction of the inferior oblique muscle.

Surgical management of V-pattern strabismus and oblique dysfunction in craniofacial dysostosis

Introduction: Strabismus affects as many as 60% to 70% of patients with craniofacial dysostosis. V-pattern strabismus with severe oblique muscle dysfunction is the most common ocular motility problem seen and can be difficult to manage. Few studies have reported on the results of strabismus surgery in this condition. Methods: We retrospectively reviewed the surgical management and outcomes of 14 patients with craniofacial dysostosis who underwent 16 operations to determine the optimal surgical procedure and to report on extraocular muscle anomalies noted at the time of surgery. Operations performed included medial rectus muscle infraplacement (n = 2), inferior oblique (IO) recession (n = 3), IO myectomy (n = 3), IO anterior transposition (n = 3), and IO denervation/extirpation (n = 5). Results: All patients had significant residual ocular motility dysfunction postoperatively. No beneficial effect was noted after IO anterior transposition or after medial rectus muscle infraplacement. Modest improvement of the V-pattern and oblique muscle dysfunction was noted after denervation/extirpation and myectomy of the IO muscle. Bilateral absent or anomalous superior oblique tendons were noted in 8 of 9 patients in whom the superior oblique tendon was examined at surgery. Conclusions: Strabismus in craniofacial dysostosis is complex and difficult to cure with surgery. Denervation/extirpation and myectomy of the IO muscle offered modest benefits, though neither procedure resulted in normalization of ocular motility. Agenesis of the superior oblique tendon may be causally related in a large proportion of affected patients. (J AAPOS 2000;4:338-42)

The relationship of rectus muscles to the globe: a study with coronal CT scanning.

Coronal computerized tomographic scans of 25 patients were reviewed in order to determine the normal relationship of rectus muscles to the globe. Using a horizontal reference line constructed along the anterior cranial fossa, the mean horizontal rectus muscle axis was found to be slightly excyclotorted in both eyes, and the mean vertical rectus muscle axis slightly incyclotorted in both eyes. In addition, the mean superior temporal quadrant angle formed by the intersection of the horizontal and vertical rectus muscle axis was significantly greater than the mean superior nasal quadrant angle in the same eye. The presence of large anatomical variations in individual patients may make it difficult to implicate rectus muscle malposition as an important etiology of A- and V-pattern strabismus.