|Year : 2016 | Volume
| Issue : 1 | Page : 65-67
A case of myopic strabismus fixus “Fixed” with loop myopexy
Sanitha Sathyan, R Jyothi
Department of Ophthalmology, Little Flower Hospital and Research Centre, Angamaly, Kerala, India
|Date of Web Publication||11-Nov-2016|
Department of Ophthalmology, Little Flower Hospital and Research Centre, Angamaly, Kerala
Source of Support: None, Conflict of Interest: None
Myopic strabismus fixus is a rare condition seen in high myopes and presents with sudden onset of strabismus. This case report describes a high myopic patient who presented with acute onset strabismus and was successfully treated with loop myopexy of superior rectus and lateral rectus muscles.
Keywords: Loop myopexy; strabismus fixus, treatment.
|How to cite this article:|
Sathyan S, Jyothi R. A case of myopic strabismus fixus “Fixed” with loop myopexy. Kerala J Ophthalmol 2016;28:65-7
| Introduction|| |
Acute onset of esotropia and hypotropia seen in the setting of high myopia is often due to herniation of globe in between the muscles, resulting in strabismus fixus. This case report discusses a patient with myopic strabismus fixus who underwent silicon band loop myopexy with good alignment postoperatively.
| Case Report|| |
A 52-year-old female, tailor by profession, presented with complaints of sudden inward deviation of left eye, which happened 9 months back. There was no h/o double vision, diminution of vision, and abnormal head posture. She was using glasses with refractive power of 16.25 DS/−0.25 DS × 179° in right the eye and − 17.50DS/−0.25 DS × 160° in the left eye.
On examination, her best corrected visual acuity was 6/9 with −16.25 DS in the right eye and 6/24 with −27.00 DS in the left eye. Abduction of the left eye was limited (−3), and there was limitation of elevation in the left eye (−2) [Figure 1].
|Figure 1: Extraocular movements showing limitation of abduction and elevation in the left eye|
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Orthoptic examination showed 50 prism diopters exotropia with left hypotropia. There was left suppression of binocular single vision. Forced duction test showed restriction of abduction and elevation in the left eye [Figure 2].
|Figure 2: Forced duction test showing restriction of elevation and abduction in the left eye|
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Anterior segment examination was normal. Fundus examination showed myopic disc and posterior vitreous detachment in both eyes. Systemic examination was within normal limits. A diagnosis of myopic strabismus fixus in the left eye was made.
Magnetic resonance imaging (MRI) of the orbit showed superotemporal herniation of the globe through the muscle cone [Figure 3].
|Figure 3: T2-weighted magnetic resonance imaging of the orbit showing superotemporal herniation of the posterior part of the globe through the muscle cone|
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She was treated with silicon band loop myopexy of the superior and lateral recti under local anesthesia [Figure 4].
|Figure 4: Silicon band loop myopexy of superior rectus and lateral rectus|
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Superior rectus and lateral rectus were isolated. A 240 silicon band was passed though the muscles and the band tied. The band was sutured to the sclera to prevent displacement. Frequency doubling technology (FDT) after myopexy was negative.
One month after the surgery, the eyes were orthotropic and abduction and elevation were normal [Figure 5].
She underwent contact lens trial and was prescribed contact lenses with refractive power −13.00 DS in the right eye and −23.00 DS in the left eye.
| Discussion|| |
Myopic strabismus fixus is a rare type of acquired strabismus in which one or both the eyes are anchored in the position of extreme adduction. This is associated with high axial myopia. The majority of patients tend to have myopia >15 D and axial length >31 mm. Myopic strabismus fixus can present in either of the two forms, namely, esotropia-hypotropia complex or exotropia-hypotropia complex.
Strabismus fixus was first described as a type of retraction syndrome – congenital structural anomaly (fibrosis of medial rectus). It was Villaseca who first described this condition as different from retraction syndromes and documented this condition as an acquired condition rather than a congenital anomaly. He suggested that fibrosis of the medial rectus is a consequence following lateral rectus paralysis rather than a primary anomaly.
Herzau and Ioannakis  were the first who demonstrated the deviation of the lateral rectus muscle paths intraoperatively. Later, orbital imaging studies by Krzizok and Schroeder  confirmed these deviated muscle paths. Superotemporal dislocation of the posterior part of the elongated globe from the muscle cone due to increased axial length causes the lateral rectus to be displaced inferiorly and the superior rectus to be displaced nasally leading to limitation of abduction and elevation, respectively. The inferior displacement of lateral rectus causes it to act as a depressor more than as an abductor, whereas nasalization of the superior rectus causes it to act as an adductor rather than as an elevating muscle. These changes lead to the patient developing esotropia and hypotropia.
In the early period, various treatment methods were tried according to the proposed cause of strabismus fixus at that time. The management techniques included medial tenotomy, disinsertion, recession-resection, Faden's operation, etc. In 2000, Yokoyama et al. proposed a loop myopexy surgery of the superior rectus and lateral rectus to correct the superotemporal dislocation of the globe. There are 3 types of loop myopexy:
- Yokoyama's procedure: Full loop myopexy of the superior rectus and lateral rectus muscle belly 15 mm behind the insertions using a polyester suture. This surgery can be combined with medial rectus muscle recession in cases of medial rectus contracture
- Yamada's procedure: Hemitransposition of the superior rectus and lateral rectus, combined with a large recession of the medial rectus, which was done in a patient with bilateral convergent strabismus fixus. They divided the superior rectus and lateral rectus in half, 15 mm from the insertion, secured the adjacent halves of the superior rectus and the lateral rectus to the sclera between the superior rectus and lateral rectus at 7 mm posterior from the limbus, and medial rectus recession was done by 8 mm 
- Partial Jenson's procedure: The partial Jensen's procedure was first performed by Larsen and Gole in 2004. They split the superior rectus and lateral rectus muscles in half, from the insertion to past the equator, and apposed the adjacent halves of the lateral rectus and superior rectus muscles. The disadvantages of suture loop myopexy included muscle strangulation, which may affect anterior ciliary circulation and may rarely cause cheese wiring of the muscle.
Wong et al., in 2005, introduced a modification of loop myopexy where silicon band loop myopexy without scleral anchorage was done with good outcomes. However, this procedure risked migration of the band. Later, a modification of this procedure was proposed by Shenoy et al. A 240 silicone band is passed through a scleral tunnel and a sleeve to unite the muscles without using anchoring sutures on the sclera. This procedure does not have the risk of anterior segment ischemia, and also is a potentially reversible procedure compared to suture loop myopexy. However, there can be a mild risk of foreign body granuloma and extrusion of the silicone sleeve.
Myopic strabismus fixus should be differentiated from sixth nerve palsy. This patient had mild restriction of elevation in addition to the restriction of abduction, which could not be explained by sixth nerve palsy. A positive forced duction test and superotemporal herniation of globe through the muscle cone, as seen in MRI, further supports the diagnosis of myopic strabismus fixus.
| Conclusion|| |
Myopic strabismus fixus should be considered in any patient with high myopia and sudden onset strabismus. Loop myopexy of superior and lateral recti provides optimum method for correction of the condition as observed in our patient.
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Conflicts of interest
There are no conflicts of interest.
| References|| |
Villaseca A. Strabismus fixus. Am J Ophthalmol 1959;48:751-62.
Herzau V, Ioannakis K. Pathogenesis of eso-and hypotropia in high myopia. Klinische Monatsblätter für Augenheilkunde 1996;208:33.
Krzizok TH, Schroeder BU. Measurement of recti eye muscle paths by magnetic resonance imaging in highly myopic and normal subjects. Invest Ophthalmol Vis Sci 1999;40:2554-60.
Yamaguchi M, Yokoyama T, Shiraki K. Surgical procedure for correcting globe dislocation in highly myopic strabismus. Am J Ophthalmol 2010;149:341-6.
Yamada M, Taniguchi S, Muroi T, Satofuka S, Nishina S. Rectus eye muscle paths after surgical correction of convergent strabismus fi xus. Am J Ophthalmol 2002;134:630-2.
Larsen PC, Gole GA. Partial Jensen's procedure for the treatment of myopic strabismus fi xus. J AAPOS 2004;8:393-5.
Wong I, Leo SW, Khoo BK. Loop myopexy for treatment of myopic strabismus fi xus. J AAPOS 2005;9:589-91.
Shenoy BH, Sachdeva V, Kekunnaya R. Silicone band loop myopexy in the treatment of myopic strabismus fi xus: Surgical outcome of a novel modifi cation. Br J Ophthalmol 2015;99:36-40.
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]