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CASE REPORT
Ahead of print publication  

Anterior transposition of inferior oblique for inferior rectus muscle aplasia


1 Department of Ophthalmology, All India Institute of Medical Sciences, Rishikesh, Uttarakhand, India
2 Department of Cardiology, All India Institute of Medical Sciences, Rishikesh, Uttarakhand, India

Date of Submission31-Jan-2018
Date of Acceptance22-May-2018
Date of Web Publication21-Aug-2018

Correspondence Address:
Anupam Singh,
All India Institute of Medical Sciences, Rishikesh - 249 203, Uttarakhand
India
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/tjo.tjo_4_18

  Abstract 


Congenital absence of extraocular muscle is rare. The most common extraocular muscle found to be congenitally absent is superior oblique followed by inferior rectus. Patients with absent inferior rectus muscle can present with abnormal head posture and incomitant hypertropia with limitation of ocular motility in the field of action of the inferior rectus with or without torticollis. Microphthalmos, microcornea, coloboma, and Axenfeld–Rieger syndrome are known to be commonly associated with inferior rectus muscle aplasia. Orbital computed tomography (CT) or magnetic resonance imaging before surgery is useful for confirmation of the diagnosis and plan of management. We report satisfactory surgical outcome of anterior transposition of inferior oblique in a case of inferior rectus aplasia with iris coloboma, microcornea, and anomalous insertion of inferior oblique. The patient had right hypertropia in primary position which increased on levoversion and left tilt. Preoperative orbital CT revealed congenital absence of inferior oblique. Peroperatively, congenital absence of inferior rectus was confirmed, and inferior oblique was found to be hyperplastic and abnormally inserted to the sclera. Anterior transposition of inferior oblique was done with satisfactory outcome.

Keywords: Absent inferior rectus, anterior transposition of inferior oblique, iris coloboma



How to cite this URL:
Singh A, Agrawal A, Mittal SK, Kumar B, Rana KM, Verma R. Anterior transposition of inferior oblique for inferior rectus muscle aplasia. Taiwan J Ophthalmol [Epub ahead of print] [cited 2019 Jul 23]. Available from: http://www.e-tjo.org/preprintarticle.asp?id=239533




  Introduction Top


Inferior rectus is the second most common extraocular muscle to be found congenitally absent after superior oblique muscle.[1],[2],[3] Inferior rectus muscle aplasia is known to be commonly associated with microphthalmos, microcornea, and coloboma.[1],[2],[3]

The patients with inferior rectus aplasia are commonly managed by vertical transposition of horizontal recti with recession or tenotomy of the superior rectus muscle.[1],[2],[3] Cooper and Greenspan first described inverse Knapp's procedure of transposing the horizontal rectus muscles in cases of absent inferior rectus muscle.[6] Taylor and Kraft reported good surgical outcome of the same procedure subsequently.[1] We report satisfactory outcome of anterior transposition of inferior oblique for case of inferior rectus aplasia associated with typical iris coloboma and microcornea.


  Case Report Top


A 22-year-old female presented to the ophthalmic outpatient department with complaints of upward deviation of the right eye since birth. She also had diminution of vision in the right eye since early childhood. The best-corrected visual acuity in the right eye was 3/60 (−0.75DS/−2 DC × 135°) and in the left eye was 6/6 (−0.50 DS). On the Krimsky test, she had 30 PD of right hypertropia in primary position which increased to 40 PD on levoversion and 50 PD on levoelevation. On the head tilt test, right hypertropia increased on left tilt. On ductions, there was ocular motility restriction in downgaze [Figure 1].
Figure 1: Preoperative nine gaze photographs of the patient showing right hypertropia increasing in right gaze and left tilt

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Slit-lamp examination revealed microcornea and typical iris coloboma in the right eye [Figure 2]. Vertical and horizontal corneal diameter of the right side was 8.5 mm × 7.5 mm and that of the left side was 10 mm × 11 mm. Axial length of the right eye was 22.20 mm and that of the left eye was 22.21 mm. On fundus examination, there was Type 3 fundal coloboma (Ida Manns classification) in the right eye. Anterior and posterior segment findings were unremarkable in the left eye. Computed tomography (CT) of the orbit revealed congenital absence of inferior rectus muscle on the right side [Figure 3]c. Forced duction test for right superior rectus was negative, but it was strongly positive for right inferior oblique. Hence, anterior transposition of inferior oblique was planned. Peroperatively, hypertrophic inferior oblique was found with abnormal insertion which was 12 mm posterior to the lower end of insertion of lateral rectus and 6 mm inferior to the lower margin of the lateral rectus muscle [Figure 3]a.
Figure 2: Slit-lamp photographs indicating right-sided microcornea and typical iris coloboma

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Figure 3: (a) Peroperative photograph showing anomalous insertion of hypertrophic inferior oblique. (b) Peroperative photograph indicating absent inferior rectus replaced by inferior rectus sheath with anterior ciliary vessels. (c) Noncontrast-enhanced computed tomography of orbit suggestive of absent right inferior rectus

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When we tried to isolate inferior rectus muscle, it could not be traced. The inferior rectus sheath with anterior ciliary vessels was present at the expected normal insertion site of the inferior rectus muscle [Figure 3]b.

Inferior oblique was sutured to sclera at 6.5 mm from limbus temporal to inferior rectus muscle sheath.

The patient had 4 PD residual hypertropia in primary position and downgaze limitation on the 1st postoperative day, and this alignment was maintained till 6 months of follow-up [Figure 4].
Figure 4: Postoperative nine gaze photographs of the patient with satisfactory primary position alignment after 6 months

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  Discussion Top


Congenital absence of extraocular muscle is not a common clinical finding. The inferior rectus is the second most common extraocular muscle found to be congenitally absent after superior oblique.[1],[2],[3] Congenital absence of the inferior rectus muscle can present as abnormal head posture with head tilt, incomitant hypertropia with limitation of ocular motility in the field of action of the inferior rectus with or without torticollis.[1],[2],[3],[4]

Microphthalmos, microcornea, coloboma, and Axenfeld–Rieger syndrome are common associations of inferior rectus aplasia.[1],[2],[3],[5] Orbital CT or magnetic resonance imaging before surgery is useful for confirmation of the diagnosis and plan of management.[1],[2],[3] Cooper and Greenspan first described inverse Knapp's procedure of transposing the horizontal rectus muscles in cases of absent inferior rectus muscle.[6] Taylor and Kraft reported good surgical outcome of the same procedure subsequently.[1]

In the present scenario, inferior transposition of horizontal recti with or without elevator weakening is the most common reported surgical procedures for achieving primary position alignment in patients with inferior rectus muscle aplasia.[2] This procedure is always at the risk of anterior segment ischemia in vascularly compromised patients, as one rectus muscle is congenitally absent. Since inferior oblique muscle does not carry ciliary vessels to the anterior segment, operating on this muscle seems to be wise and relatively safe surgical option.

Parvataneni and Olitsky reported a series of six patients treated with unilateral anterior transposition of the inferior oblique muscle with resection up to 8 mm for lost inferior rectus muscle.[7] They found unilateral anterior transposition of the inferior oblique muscle as an effective procedure in the treatment of a lost inferior rectus muscle.

Yang and Guo reported retrospective case series of five patients of absent inferior rectus muscle treated with anteriorization of inferior oblique muscle combined with recession of superior rectus.[8] Orthophoria was achieved in four patients, whereas one patient had 10 PD of hypotropia.

On anterior transposition of the inferior oblique muscle, its neurovascular bundle becomes taut rather than lax changing its function from an elevator to an inferior anchor of the globe.[9] This procedure has been used to treat unilateral hypertropia in patients of dissociated vertical deviation and unilateral lost or aplastic inferior rectus muscle.[7]

In our case, the patient had right hypertropia in primary position which increased on levoversion and left tilt with downgaze restriction. On imaging and surgical exploration right inferior rectus was absent explaining the hypertropia and downgaze restriction. In addition, the patient had abnormal insertion of ipsilateral inferior oblique. Primary position alignment within 4 PD with residual downgaze limitation was achieved with anterior transposition of inferior oblique. This alignment was maintained up to 6 months of follow-up.

Hence, we conclude that anterior transposition of inferior oblique muscle for absent inferior rectus is a relatively safe surgical option as compared to inferior transposition of horizontal recti.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

The authors declare that there are no conflicts of interests of this paper.



 
  References Top

1.
Taylor RH, Kraft SP. Aplasia of the inferior rectus muscle. A case report and review of the literature. Ophthalmology 1997;104:415-8.  Back to cited text no. 1
    
2.
Astle WF, Hill VE, Ells AL, Chi NT, Martinovic E. Congenital absence of the inferior rectus muscle – Diagnosis and management. J AAPOS 2003;7:339-44.  Back to cited text no. 2
    
3.
Matsuo T, Watanabe T, Furuse T, Hasebe S, Ohtsuki H. Case report and literature review of inferior rectus muscle aplasia in 16 Japanese patients. Strabismus 2009;17:66-74.  Back to cited text no. 3
    
4.
Almahmoudi F, Khan AO. Inferior oblique anterior transposition for the unilateral hypertropia associated with bilateral inferior rectus muscle aplasia. J AAPOS 2014;18:301-3.  Back to cited text no. 4
    
5.
Bhate M, Martin FJ. Unilateral inferior rectus hypoplasia in a child with Axenfeld-Rieger syndrome. J AAPOS 2012;16:304-6.  Back to cited text no. 5
    
6.
Cooper EL, Greenspan JA. Congenital absence of the inferior rectus muscle. Arch Ophthalmol 1971;86:451-4.  Back to cited text no. 6
    
7.
Parvataneni M, Olitsky SE. Unilateral anterior transposition and resection of the inferior oblique muscle for the treatment of hypertropia. J Pediatr Ophthalmol Strabismus 2005;42:163-5.  Back to cited text no. 7
    
8.
Yang S, Guo X. Treatment of large hypertropia following absence of inferior rectus by integrated anteriorization of inferior oblique combined with recession of superior rectus. Zhonghua Yan Ke Za Zhi 2015;51:424-8.  Back to cited text no. 8
    
9.
Stager DR, Weakley DR Jr., Stager D. Anterior transposition of the inferior oblique. Anatomic assessment of the neurovascular bundle. Arch Ophthalmol 1992;110:360-2.  Back to cited text no. 9
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]



 

 
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