affected by bilateral and incomplete facial nerve palsy, impeding them socially, given their inability to convey reactions of joy or sorrow. 3 Table I below summarizes clinical features that have been reported in cases of Möbius Synrome.
Möbius syndrome has been reported to usually occur sporadically but some heterogeneous inheritance patterns have been observed in several affected families. 2 The exact pathogenesis remains unclear and controversial. Fetal exposure to teratogens, disturbance in rhombencephalic development or acquired ischemic events occurring shortly after the fifth week in utero have all been proposed. 1,2 The insult is thought to lead to a chain of events involving a temporary interrup-tion in the fetal blood supply to the lower brainstem. This then causes one or more focal areas of damage. 2 The facial, abducens, lacrimal and salivary nuclei are all located in the involved brainstem. They also tend to develop simultaneously in this phase of embryogenesis. This theory is supported by many studies that have found hypoplasia of the lower brainstem with flattening of the floor of the 4th ventricle in ap-proximately 30 % of cases of Möbius syndrome. They’ ve also found gliosis and calcifactions in the same area. 2 The general concensus is that Möbius syndrome is a complex and multifactorial developmental disor-der of the lower part of the brain-stem. Möbius patients are often categorized according to the severity of their abnormalities. Defining the syndrome is confusing at times given the highly heterogeneous presentation. 1 Despite its wide spectrum of abnormalities, most patients with Möbius syndrome will present with orofacial findings including micrognatia, cleft palate, tongue anomalies, ear malforma-tions and bifid uvula( split uvula). 5
Ocular findings related to Möbius include severe limitations in abduction, with marked decrease of horizontal saccades, similar to a gaze paresis, most likely due to a supranuclear lesion. 3 Consequently, reading problems can occur. Other findings include epicanthal folds, and more rarely hypertelorism, coloboma, heterochromia, heterochromic cyclitis, nystagmus and limbal dermoids. 1 A significant loss of corneal sensitivity can occur as a result of the trigeminal nerve palsy( V). This nerve, which provides sensory innervation to the cornea, also allows constant renewal of epithelial cells. Surface squamous cells are constantly sloughing off every day; this process of continual renewal of cells is imperative for ocular surface integrity. In neurotrophic keratopathy, the cornea is deprived of sensation and does not produce and renew cells, but the normal loss of cells still occurs. In addition, the corneal reflex is attenuated, result-ing in reduced protection of the ocular surface through a lack of blinking. Patients with neurotrophic keratopathy have worse signs than
Table I: Clinical Features Reported in Cases with Möbius Syndrome4 System Neurological
Features Mental retardation, CNS abnormalities, Hypotonia, Epilepsy
Craniofacial Cranium shape defect, Bitemporal narrowing, Epicanthic folds, Hypertelorism, Ptosis, Strabismus, Microphthalmia, Duane anomaly, Lacrimal duct defects, Flat nasal bridge, Teeth anomalies, Highly arched palate, Bifid uvula / cleft palate, Small tongue, Micrognathia, External ear defects, Low set ears, Short neck
Cranial nerves
Palsies: III, IV, V, VI, VII, VIII, IX, X, XII
Trunk Poland anomaly, Congenital heart defect, Vertebral abnormalities, Kyphoscoliosis, Aplasia abdominal muscles, Underdeveloped genitalia
Limbs Brachydactyly, Clinodactyly, Camptodactyly, Syndactyly, Ectrodactyly, Low set thumbs, Adducted thumbs, Supernumerary thumb, Flexion deformities of wrist, Hip defects / luxation, Hypoplasia of lower legs, Arthrogryposis, Clubfoot, Pes planus
Skin Hemangiomas symptoms and are therefore at risk for corneal ulceration, resulting in severe and irreversible vision loss. 6 If the facial nerve is also affected, lagophthalmos, an incomplete closure of the eyelids while blinking, may result. 2,4 This case report explores how optometrists can help restore vision and protect the ocular surface in these patients using LDRGP.
The concept of neutralizing the refractive error induced by the cornea with an enclosed reservoir of liquid was first introduced in 1508 by Leonardo da Vinci. 7 Scleral
42 Vol 75 | No 2 2013 C a n a d i a n J o u r n a l o f O p t o m e t r y | R e v u e c a n a d i e n n e d’ o p t o m é t r i e