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