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 Table of Contents  
CASE REPORT
Year : 2022  |  Volume : 2  |  Issue : 2  |  Page : 522-524

Squint surgery in a case of osteogenesis imperfecta


Department of Pediatric Ophthalmology and Strabismus, Sankara Eye Hospital, Bengaluru, Karnataka, India

Date of Submission01-Jun-2021
Date of Acceptance06-Jul-2021
Date of Web Publication13-Apr-2022

Correspondence Address:
Sowmya Raveendra Murthy
Consultant, Department of Pediatric Ophthalmology and Strabismus, Sankara Eye Hospital, Bengaluru - 560 037, Karnataka
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijo.IJO_1520_21

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  Abstract 


Osteogenesis imperfecta (OI) is well known to be associated with blue sclera due to thinning along with skeletal deformities. Not all cases of OI have blue sclera despite having a thinner sclera than in normal individuals. We are presenting a case report of a 28-year-old girl with intermittent exotropia and OI with no evidence of blue sclera. On AS-OCT, scleral thinning was noted at the level of medial rectus muscle insertion. The patient underwent successful recession-resection surgery for the same. The thin sclera and OI need not deter the decision to operate on squint, and a successful squint surgery is possible in eyes with some amount of scleral thinning with careful suturing.

Keywords: Osteogenesis imperfecta, scleral thinning, squint surgery


How to cite this article:
Raghu N, Murthy SR. Squint surgery in a case of osteogenesis imperfecta. Indian J Ophthalmol Case Rep 2022;2:522-4

How to cite this URL:
Raghu N, Murthy SR. Squint surgery in a case of osteogenesis imperfecta. Indian J Ophthalmol Case Rep [serial online] 2022 [cited 2022 May 18];2:522-4. Available from: https://www.ijoreports.in/text.asp?2022/2/2/522/342887



Osteogenesis imperfecta (OI) is an inherited condition caused by a defect in the genes responsible for collagen I synthesis. It is classified into four predominant types based on the clinical findings and genetics.[1] Type 1 is the least severe form, associated with blue sclera and autosomal dominant in inheritance. They present with multiple recurrent fractures, short stature, and teeth abnormality (dentinogenesis imperfect). This type has been reported with white sclera as well.[1] Type 2 is associated with perinatal death due to pulmonary aplasia and rib fractures. Type 3 is the most severe and is autosomal recessive in inheritance. Lastly, type 4 is often associated with white sclera and skeletal deformity and is also autosomal dominant, presenting with fractures in adult life due to osteopenia. The severity of deformity is not seen to be proportional to blue sclera.[2]

The ophthalmic manifestations, in addition to thinning of sclera, include congenital glaucoma, megalophthalmos, ectopia lentis, vitreous hyperplasia, subhyaloid hemorrhage, retinal detachment,[3] and rarely with exotropia and ptosis.[4]

The cause of blue sclera is the thinning of sclera leading to increased light transmission and visualization of the underlying vascular choroid. Another theory is that the abnormal arrangement of collagen leads to light scattering and the appearance of a blue hue similar to the blueness of the sky.[1]

This thinning of the sclera becomes a concern during surgeries such as squint surgeries due to the requirement of scleral sutures. Here we report a case of exotropia with OI which was successfully operated for the same.


  Case Report Top


A 28-year-old girl presented to us with deviation of either eye since childhood. She was known to have dentinogenesis imperfecta and a family history of OI in her mother and sister, who have bony and dental deformities. On examination, she was found to have short stature, scoliosis, and had been diagnosed with osteopenia. Based on positive family history, dental abnormalities, and scoliosis, the diagnosis of OI was made and confirmed by the orthopedician. Her best-corrected visual acuity was 20/20, N6 in both eyes. She did not have blue sclera.

Worth 4 dot tests showed fusion for distance and near. Alternate prism cover test (APCT) was done, which showed exotropia measuring 55 PD for distance and 60–65 PD for near with preference for the right eye. The angle measured 45–50 PD exotropia in downgaze and 60–65 PD in upgaze with no horizontal gaze incomitance. Ocular movements showed overelevation in adduction of 3+ in both eyes [Figure 1]. In view of OI, anterior segment optical coherence tomography using Topcon spectral-domain OCT was done to ascertain scleral thickness at level of muscle insertions of medial rectus (MR) and lateral rectus (LR) as MR would be sutured at the insertion. Further, the thinnest part of the sclera is just behind the insertion of the recti; thus, measurements taken at insertion will give lowest scleral thickness. The measurement at planned recession sites of LR was not possible owing to the limitations of the anterior segment OCT. The sclera was thinner than expected at the level of MR insertion in the left eye. It measured 198–230 microns in the left eye and 230–260 microns in the right eye [Figure 2]. The thickness at LR insertion in both eyes was in the range of 370–400 microns.
Figure 1: Preoperative nine gaze picture showing exotropia in primary gaze with inferior oblique overaction (OU)

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Figure 2: AS-OCT images showing thinning of sclera at the level of medial rectus insertion in the left eye (a) and right eye (b)

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Surgical plan of bilateral LR recession 8 mm and IO recession with left eye MR resection of 6.5 mm under local anesthesia was made. Plication was contemplated if thinning was noted on table. Further plan to take longer and thinner scleral bites with reinforcement with fibrin glue was considered in view of the thin sclera. On table, the LR tendon of both eyes appeared thin, though measurement was not done. Scleral thinning with a bluish hue was noted in both eyes below LR muscle insertion. Careful sutures were taken for MR resection and LR recession (Dr SR). Despite the large angle of squint, adjustable sutures were avoided due to the increased risk of scleral perforation with repeated manipulation at the area of thinning. The surgery was uneventful, routine post-op medications were started, and the patient was doing well. No thinning was noted in the subsequent visit.

Postoperatively, the patient was orthophoric for distance and 7 PD exophoria for near was noted at 1 month [Figure 3].
Figure 3: Postoperative nine gaze picture showing orthotropia in primary gaze

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  Discussion Top


Ophthalmic surgery involving scleral sutures in patients with OI is worrisome because of the risk of scleral perforation. However, not all cases with thin sclera present with blue discoloration of the eyes. Also, not all cases of OI present with blue sclera, and this is irrespective of the severity of bony deformities.[2]

A case report by Pirouzian et al. Described a scleral perforation in a patient with OI during squint surgery.[5] The patient had blue sclera along with right hypertropia and excyclotorsion. After successful IO myectomy, when an exaggerated traction test was repeated, a full-thickness scleral perforation was noted adjacent to the nasal limbus. Though the anterior chamber was well formed intraoperatively, the post-op period had shallow anterior chamber with choroidal effusion. The patient did well after scleral patch graft, which stood out starkly against the patient's blue sclera. Another case series by Salcone et al. Described both spontaneous and traumatic scleral perforations in patients with OI.[6]

There has also been a report of successful scleral buckling done in a case of OI with blue sclera. A 277 segmental circumferential buckle was used and sutured with 5-0 nylon sutures. Single mattress sutures were placed in each quadrant.[7] Another article on buckling in patients with OI reported scleral perforation because of which the surgery had to be abandoned.[8] Church et al.[9] also reported buckle surgery in OI where they sutured the buckle at the muscle insertion and not to the sclera itself.

The above reports highlight the challenges associated with taking scleral sutures in patients with OI.

Our patient was probably a case of type 1 OI. Her scleral thickness at the level of insertion of MR was approximately 198–230 microns. Taking into account that she is myopic, the expected thickness is still below the expected range as seen by Dhakal et al.[10]


  Conclusion Top


We propose that taking scleral thickness measurements by using AS-OCT can be a useful adjunct in these patients before planning surgery. Also, a successful squint surgery is possible in patients of OI; however, it needs care during taking scleral sutures.

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

There are no conflicts of interest.



 
  References Top

1.
Sillence DO, Senn A, Danks DM. Genetic heterogeneity in osteogenesis imperfecta. J Med Genet 1979;16:101-16.  Back to cited text no. 1
    
2.
Sillence D, Butler B, Latham M, Barlow K. Natural history of blue sclerae in osteogenesis imperfecta. Am J Med Genet 1993;45:183-6.  Back to cited text no. 2
    
3.
Keles A, Doguizi S, Sahin NM, Koç M, Aycan Z. Anterior segment findings in patients with osteogenesis imperfecta: A case-control study. Cornea 2020;39:935-9.  Back to cited text no. 3
    
4.
Chen P, Chen J, Yang Z, Lu Y, Shen L, Zhou K, et al. Consanguineous-derived homozygous WNT1 mutation results in osteogenesis imperfect with congenital ptosis and exotropia. Mol Genet Genomic Med 2020;8:e1350.  Back to cited text no. 4
    
5.
Pirouzian A, O'Halloran H, Scher C, Jockin Y, Yaghmai R. Traumatic and spontaneous scleral rupture and uveal prolapse in osteogenesis imperfecta. J Pediatr Ophthalmol Strabismus 2007;44:315-7.  Back to cited text no. 5
    
6.
Salcone EM, Hamdy S, Melki S, Hunter DG. Scleral perforations during routine traction test in a patient with osteogenesis imperfecta. J AAPOS 2014;18:610-2.  Back to cited text no. 6
    
7.
Fleissig E, barak A. Surgical management of retinal detachment in osteogenesis imperfecta: case report and review of the literature. Retin Cases Brief Rep 2019 winter;13(1):43-46. Doi: 10.1097/icb.0000000000000527.  Back to cited text no. 7
    
8.
Eliott D, Rezai KA, Dass AB, Lewis J. Management of retinal detachment in osteogenesis imperfecta. Arch Ophthalmol 2003;121:1062-4.  Back to cited text no. 8
    
9.
Church JR, Winder SM. Surgical repair of a retinal detachment in a patient with osteogenesis imperfecta. Retina 2006;26:242-3.  Back to cited text no. 9
    
10.
Dhakal R, Vupparaboina KK, Verkicharla PK. Anterior sclera undergoes thinning with increasing degree of myopia. Invest Ophthalmol Vis Sci 2020;61:6.  Back to cited text no. 10
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]



 

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