Selective aplasia of global fibres of all extraocular muscles in congenital fibrosis of extraocular muscles (CFEOM): a rare presentation

摘要

A 15-year-old boy presented in our strabismus clinic with complaints of bilateral ptosis and limitation of ocular movements since birth. He had a positive family history of consanguinity and similar ocular movement abnormalities in his three siblings. There was no history of systemic illness. Physical examination showed normal growth parameters without craniofacial dysmorphism except blepharoptosis and lagophthalmos in both eyes, more marked in the right eye. Right eye best-corrected visual acuity (BCVA) was 6/12 and left eye BCVA was 6/9. Slit-lamp biomicroscopy of right eye showed exposure keratopathy, rest was unremarkable. Fundus examination was within normal limits, with no pigmentary retinopathy or optic atrophy changes. There was almost total external ophthalmoplegia, with normal reacting pupils to both direct and consensual light reflex in each eye. The patient preferred fixation with the left eye as his right eye had severe ptosis covering the pupillary area. The patient had chin up and 15° right head tilt position with 30 prism dioptre (PD) exotropia and 14 PD hypertropia in the right eye in primary position. Right eye medial rectus resection with downshift to inferior rectus was planned to improve exotropia and hypertropia in primary gaze. Intraoperatively, the medial quadrant was explored to hook the medial rectus muscle but no muscle fibres were found. Further dissection was carried out to explore the other three recti and the oblique muscles. On careful exploration of scleral surface, no muscle fibres were identified, except for the presence of the anterior ciliary vessels at the insertion site of muscles, suggesting the absence of all extraocular muscles (figure 1). CT imaging and MRI disclosed the presence of extraocular muscles at the orbital apex that were abnormally thin and cord-like structure until the equator and missing beyond that. This was seen in both the eyes (figure 2).