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 Table of Contents  
CASE REPORT
Year : 2021  |  Volume : 1  |  Issue : 4  |  Page : 768-770

Strabismus fixus associated with congenital orbital fibrosis in children


Pediatric Ophthalmology and Strabismus Department, Tianjin Eye Hospital; Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Institute; Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China

Date of Submission09-Dec-2020
Date of Acceptance10-May-2021
Date of Web Publication09-Oct-2021

Correspondence Address:
Dr. Yueping Li
4# Gansu Road, Heping District, Tianjin - 300020
China
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijo.IJO_3646_20

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  Abstract 


Congenital orbital fibrosis with strabismus fixus is a very rare clinical condition. Although surgery is used to treat strabismus fixus caused by congenital orbital fibrosis, it does not improve ocular motility after removal of extraocular muscles. Here, we describe cases of congenital restrictive strabismus caused by orbital maldevelopment. Specifically, we describe the clinical characteristics and magnetic resonance imaging features of strabismus fixus caused by congenital orbital fibrosis.

Keywords: Congenital orbital fibrosis, strabismus, surgery


How to cite this article:
Hao R, Li Y, Zhao K. Strabismus fixus associated with congenital orbital fibrosis in children. Indian J Ophthalmol Case Rep 2021;1:768-70

How to cite this URL:
Hao R, Li Y, Zhao K. Strabismus fixus associated with congenital orbital fibrosis in children. Indian J Ophthalmol Case Rep [serial online] 2021 [cited 2021 Oct 28];1:768-70. Available from: https://www.ijoreports.in/text.asp?2021/1/4/768/327686



Congenital orbital fibrosis is a congenital disorder characterized by severe restrictive ophthalmoplegia and pseudoptosis.[1],[2] Strabismus fixus is a rare misalignment, which can be caused by congenital fibrosis of extraocular muscles,[3] or congenital orbital fibrosis,[4] or maldevelopment of orbital structures.[2] Strabismus fixus caused by congenital orbital fibrosis is difficult to treat. For instance, surgery does not improve ocular motility. In this report, we have reviewed the medical records and magnetic resonance imaging (MRI) findings of three patients with strabismus fixus caused by congenital orbital fibrosis in the Department of Pediatric Ophthalmology and Strabismus, Tianjin Eye Hospital, between 2018 and 2019.


  Case Reports Top


Case 1

An 8-year-old girl presented with fixus esotropia and mild enophthalmos on the right eye since birth with abnormal head position. Her face was tilted to the right, whereas the head slightly tilted to the left [Figure 1]a. A review of her records revealed uneventful full-term delivery with a negative medical and family history. On examination, her palpebral fissure height was asymmetric, cycloplegic refraction was +2.00 DS +1.75 DC × 5 right eye and −0.75 DS + 0.25 DC × 10 left eye, with best-corrected visual acuity of 20/25 OD and 20/20 OS. Exophthalmometry showed 11.5 mm OD and 13.5 mm OS. In addition, 30 PD right esotropia and 4 PD right hypertropia were seen. Fundus examination showed that the boundary of optic disc was not clear and retinal vessels were tortuous [Figure 1]b. Ocular motility examination revealed impaired abduction, supraduction, and infraduction of right eye (not pass the middle line) [Figure 1]d. An MRI scan found an abnormal signal within the retrobulbar space of right orbit which involved the four rectus extraocular muscles [Figure 1]c. An MRI of the brainstem was normal bilaterally.
Figure 1: Case 1: (a) Abnormal head position; (b) Fundus examination showed that the boundary of optic disc was not clear and retinal vessels were tortuous of right eye; (c) MRI scan found an abnormal signal within the retrobulbar space of right orbit which involved the four rectus extraocular muscles; (d) Ocular motility examination revealed impaired abduction, supraduction, and infraduction of right eye; (e) The deviation in the primary gaze and abnormal head position improved after operation

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Forced duction test performed during operation showed moderate limitation in all directions on right eye [Video 1]. Similar results were obtained when the right medial rectus muscle was released after placement of sutures [Video 2]. The medial rectus 5.5 mm was resected and lateral rectus 6 mm was recessed with adjustable suture technique. The deviation in the primary gaze and abnormal head position improved after operation, but ocular movement was still limited [Figure 1]e.







Case 2

A 2-year-old boy presented with mild ptosis with enophthalmos and severely restricted ocular movement on right eye since birth [Figure 2]a. The patient had a negative family history and medical history with good general health and had a natural birth. On examination, cycloplegic refraction was +1.50 OS, and the right eye was not refracted due to fixus esotropia in the primary gaze. Duction test revealed severe limitation in all directions. Exophthalmometry showed 10 mm OD and 13 mm OS. MRI images obtained under anesthesia showed an abnormal signal within the muscle cone, involving Tenon's capsules and adherent to all extraocular rectus muscles [Figure 2]c. Results of MRI scan of the brainstem were normal.
Figure 2: Case 2: (a) Ocular movement on right eye; (b) Eye alignment in the primary gaze after a 2-month follow-up; (c) MRI images showed an abnormal signal within the muscle cone, involving Tenon's capsules and adherent to all extraocular rectus muscles of right eye

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The right eye was operated to improve the ocular alignment in the primary gaze. Forced duction test during the surgery showed that the right medial rectus muscle was too tight to hook; hence, we cut and freed the medial rectus muscle to release the constraining factors around globe. This alignment improved in the primary gaze after a 2-month follow-up [Figure 2]b. Cycloplegia refraction measurement revealed +10.00 DS OD. Subsequently, we asked the parents to patch the left eye and follow up vision acuity and ocular alignment.

Case 3

A 6-year-old boy presented with moderate ptosis with enophthalmos on right eye since birth. The patient was born uneventfully at full-term and had a negative family and medical history. On examination, right hyperopia was found in the primary gaze. The axial length was 19.8 mm for right eye and 22.5 mm for the left eye. Cycloplegic refraction was +5.70 DS +1.00 DC × 95 OD and +1.50 OS. The best-corrected visual acuity was 20/100 for the right eye and 20/20 for the left eye. Exophthalmometry showed 11.2 mm OD and 14.7 mm OS. Duction test showed restricted hypertropia and severe limitation in terms of infraduction, abduction, and adduction [Figure 3]a. MRI scan images showed a linear band posterior global extending from the orbital apex [Figure 3]b. We suggested that the patient undergo correction of refractive error and occluded therapy to improve visual acuity.
Figure 3: Case 3: (a) Duction showed restricted hypertropia and severe limitation in terms of infraduction, abduction, and adduction of right eye; (b) MRI scan images showed a linear band posterior global extending from the orbital apex of right eye.

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  Discussion Top


MRI was applied to explore the underlying cause of restrictive motility, which revealed low signal noise in the retrobulbar areas. Strabismus surgery was performed for two cases which resulted in good alignment in primary position. Surgery can improve ocular alignment in primary gaze and/or abnormal head position; however, it does not improve ocular motility.

In the present cases of congenital orbital fibrosis, the length of ocular axis was shorter, probably because the eyeball growth was limited by the retrobulbar mass. Fixus strabismus caused by congenital orbital fibrosis differs from strabismus caused by high myopia, which is usually characterized by progressive esotropia and hypotropia with limitation on supraduction and abduction on eye with severe myopia, resulting from enlarged length of ocular axis and disruption of the ligament band between superior rectus pulley and lateral rectus pulley, a condition known as myopic strabismus fixus or heavy eye syndrome.[5],[6] Cases of progressive esotropia or convergent strabismus fixus and restricted extraocular movement without high myopia have been reported, which are considered to be subtypes of congenital extraocular muscle fibrosis.[7],[8] In the present cases of congenital orbital fibrosis, the length of ocular axis was shorter probably due to the limited eyeball growth by the retrobulbar mass, hence, the manifested hyperopia and amblyopia. For case 1, hyperopia was less severe than for cases 2 and 3. Notably, case 2 had severe hyperopia which may be caused by intraorbital fibrosis and extraocular muscle involvement.

Blurred optic disc margins caused by retrobulbar fibrosis mass contraction were seen in some patients, but MRI images of oculomotor and abducens nerves were normal; this condition is traditionally considered as a subtype of congenital fibrosis of the extraocular muscles (CFEOM).[9] By comparing the clinical and radiological findings of congenital orbital fibrosis and CFEOM, Kim et al.[10] found that congenital orbital fibrosis is a unique disease with distinct features from CFEOM. In our study, all cases showed varying degrees of enophthalmos, unlike CFEOM which lacks significant enophthalmos at the primary gaze despite extraocular muscle fibrosis. However, enophthalmos in the primary gaze should be differentiated from Duane syndrome which is characterized by limitation of abduction or/and adduction, with globe retraction and palpebral fissure narrowing. Patients with Duane syndrome may also have a face turn. High-definition MRI has shown the absence of abducens nerve/nucleus and secondary changes in the extraocular muscles in such patients.[11] In our study, enophthalmos presented with primary gaze, whereas the palpebral fissure did not change with ocular motility, which differs from the Duane syndrome.


  Conclusion Top


In the present cases, congenital orbital fibrosis was found to be an isolated orbital disease without genetic background, characterized with ocular movement limitation in all gazes. Hyperopia is caused by the retrobulbar mass that may limit the eyeball growth. MRI scan can be of help in the differential diagnosis. Given that the etiology remains unknown, further studies are needed to reveal the pathomechanisms of the disease.

Ethical committee approval

The ethical Committee of Tianjin Eye Hospital approved this study. All research adhered to the tenets of the Declaration of Helsinki.

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

Rui Hao was supported by National Natural Science Foundation of China (Grant number: 81800861).

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Leone C Jr, Weinstein G. Orbital fibrosis with enophthalmos. Ophthalmic Surg 1972;3:71-5.  Back to cited text no. 1
    
2.
Mavrikakis I, Pegado V, Lyons C, Rootman J. Congenital orbital fibrosis: A distinct clinical entity. Orbit 2009;28:43-9.  Back to cited text no. 2
    
3.
Merino P, Gómez de Liaño P, Fukumitsu H, Franco G, Ruiz Y. Congenital fibrosis of the extraocular muscles: Magnetic resonance imaging findings and surgical treatment. Strabismus 2013;21:183-9.  Back to cited text no. 3
    
4.
Li Y, Han J, Yan H, Li J, Wang D, Xu S. Congenital orbital fibrosis associated with fibrosis of extraocular muscle. BMJ Case Rep 2012;2012:bcr2012006384.  Back to cited text no. 4
    
5.
Ward DM. The heavy eye phenomenon. Trans Ophthalmol Soc UK 1967;87:717-26.  Back to cited text no. 5
    
6.
Ko J, Lee HJ, Lee JS, Yoon JS. Congenital orbital fibrosis: Molecular genetic analysis by whole-exome and mitochondrial genome sequencing. Yonsei Med J 2017;58:1078-80.  Back to cited text no. 6
    
7.
Weir CR, Cleary M, Stewart H. Progressive esotropia and restricted extraocular movements associated with low myopia. Strabismus 2007;15:111-2.  Back to cited text no. 7
    
8.
Mendonca TM, Tiberwala S, Sachdeva V, Kekunnaya R. Convergent strabismus fixus without high myopia. J AAPOS 2016;20:83-5.  Back to cited text no. 8
    
9.
Yazdani A, Traboulsi EI. Classification and surgical management of patients with familial and sporadic forms of congenital fibrosis of the extraocular muscles. Ophthalmology 2004;111:1035-42.  Back to cited text no. 9
    
10.
Kim N, Yang HK, Kim JH, Hwang JM. Comparison of clinical and radiological findings between congenital orbital fibrosis and congenital fibrosis of the extraocular muscles. Curr Eye Res 2018;43:1471-6.  Back to cited text no. 10
    
11.
Gupta C, Sharma P, Saxena R, Garg A, Sharma S. Clinical correlation of imaging findings in congenital cranial dysinnervation disorders involving abducens nerve. Indian J Ophthalmol Case Rep2017;65:155-9.  Back to cited text no. 11
    


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  [Figure 1], [Figure 2], [Figure 3]



 

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