From Guru Nanak Eye Centre, Maulana Azad Medical College, University of Delhi, New Delhi, India.
Address correspondence to Daraius Shroff, MBBS, E-22A, East of Kailash, New Delhi 110065, India.
Congenital fibrosis of the extraocular muscles is a congenital ocular motility disorder manifesting broadly as restrictive external ophthalmoplegia and ptosis.1 A-patterns, globe retraction, and convergence in up gaze, incyclotorsion, and anomalous head posture (most commonly a chin-up position) have been described in congenital fibrosis of the extraocular muscles.1–3
We report excyclotorsion contributing to loss of binocularity and amblyopia and causing ipsilateral head tilt to counter excyclotorsion, along with findings on computed tomography and surgical exploration in a case of congenital fibrosis of the extraocular muscles type 1.
An 18-year-old girl presented with limitation of elevation of both eyes. She had anomalous head posture comprising head tilt to the right and chin elevation, ptosis in both eyes, and poor vision in the left eye since early childhood. The family history was negative for similar complaints and consanguinity.
The uncorrected visual acuity in the right eye was 20/20 and the best-corrected visual acuity with −1.5 cylinder at 90° degrees was 20/200 in the left eye. She had a 15° tilt to the right side with chin-up posture and bilateral symmetrical ptosis with poor Bell’s phenomenon. There was a right hypertropia of 20 prism diopters (PD) with no horizontal deviation in the primary position. On attempted up gaze, esodeviation of 55 PD with A-pattern was observed. On down gaze, an exodeviation of more than 50 PD was noted. Motility evaluation showed bilateral underacting inferior recti and overacting superior oblique muscles. Horizontal movements were full (Fig. 1A). No nystagmus was noted. Pupils were normal with no light near dissociation. There were no signs of exposure keratitis.
Figure 1. (A) Preoperative and (B) Postoperative Nine Gaze Photographs and Frontal View of the Face. Note the Preoperative Head Tilt, A-Pattern, and Restricted up Gaze. Postoperatively, the Anomalous Head Posture Was Relieved, with Improved Motility and Reduced Convergence on Attempted up Gaze.
Double Maddox rod test did not reveal any subjective torsion. Fundus photography (Fig. 2A) showed excyclotorsion in the right eye of 18° by the method described by Bixenman and von Noorden.4 There was restriction to elevation in both eyes with forced duction testing. Fusion was absent on the Worth four-dot test.
Figure 2. (A) Preoperative and (B) Postoperative Fundus Photographs Showing Objective Excyclotorsion. Excyclotorsion Has Been Reduced Postoperatively. (C) Computed Tomography Scan Showing Reduced Volume and Marked Thinning of Bilateral Superior Rectus and Levator Palpebrae Superioris Muscles. Other Extraocular Muscles Appear Normal.
Coronal section orbital computed tomography scans using a soft tissue window revealed marked thinning of bilateral superior rectus and levator palpebrae superioris muscles; all other extraocular muscles were normal (Fig. 3). No abnormality was noted in the mid brain or pons. A diagnosis of congenital fibrosis of the extraocular muscles type 1 was made. Chromosomal studies were not done.
On surgical exploration, bilateral fibrotic inferior recti and tight superior oblique tendon in the right eye were encountered. The left inferior rectus was recessed 10 mm and the right inferior rectus was recessed 6 mm from the insertion with one muscle width nasal transposition. The right superior rectus was resected 4 mm and transposed temporally one muscle width. The Harada–Ito procedure was done on the right superior oblique tendon. Postoperatively, anomalous head posture was relieved and excyclotorsion was reduced to 12° (Figs.1B and 2B).
Abnormal head posture and primary position deviation are the main reasons for surgical intervention in congenital fibrosis of the extraocular muscles. Anomalous head posture consists of a chin-up position, face turn, or head tilt in most cases. Head tilts are usually caused by primary position hypertropia, abnormal torsion due to innervational and mechanical abnormalities of extraocular muscles, dissociated vertical deviation, or nystagmus.
To our knowledge, excyclotorsion has not been reported in congenital fibrosis of the extraocular muscles. Only one report on congenital fibrosis of the extraocular muscles mentions incyclotorsion in two cases with synergistic divergence.2 Extorsional movements have been previously reported5,6 but not torsional strabismus in association with nystagmus or nystagmoid movements.
Abnormal conjugate torsion (with one eye incyclotorted and the other eye excyclotorted) could be generated by skew deviation and ocular tilt reaction due to pathologies of the mid brain, pons, or medulla, whereas disjugate torsion (both eyes incyclotorted or excyclotorted) would be seen in third and fourth nerve palsies. Our case falls into the latter category.
The coexistence of excyclotorsion and A-pattern in this case seems to be perverse because V-pattern is seen with excyclotorsion and A-pattern with incyclotorsion. There could be differing mechanisms for both.
Bilateral excyclotorsion in this case could be caused by hypoplastic superior recti as revealed on computed tomography, sagitallized superior oblique tendons, and tight inferior recti. The A-pattern with convergence on attempted up gaze and divergence on down gaze could be innervational in our case due to substitution of up gaze by convergence and down gaze by divergence.7
Despite performing the Harada–Ito procedure on the superior oblique tendon and surgery on both vertical recti with transposition, torsion was not fully eliminated. A greater amount of surgery seems to be indicated to correct torsion in congenital fibrosis of the extraocular muscles.
Head tilt, loss of binocularity, and amblyopia may result due to torsional strabismus. Because the superior division of the oculomotor nerve is implicated in congenital fibrosis of the extraocular muscles type 1, excyclotropia would be expected to occur. Evaluation of objective torsion may help us characterize congenital fibrosis of the extraocular muscles better and may impact its evaluation and management.
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- : Kim JH, Hwang JM. Hypoplastic oculomotor nerve and absent abducens nerve in congenital fibrosis syndrome and synergistic divergence with magnetic resonance imaging. Ophthalmology. 2005; 112:728–773. doi:10.1016/j.ophtha.2004.12.006 [CrossRef]
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