title: Ophthalmic features of Joubert syndrome.
abstract: OBJECTIVE
  Joubert syndrome (Online Mendelian Inheritance in Man 213300) is a rare autosomal recessive congenital malformation of the brainstem and cerebellar vermis. Diagnosis is based on characteristic clinical features (e.g., hypotonia, episodic hyperpnea, developmental delay, progressive ataxia) and is confirmed by distinctive neuroradiologic findings (e.g., the "molar tooth" sign). Variable ophthalmic features have been mentioned in prior reports; however, most do not detail eye findings and the few that do were before the publication of suggested diagnostic criteria. The objective of the current study is to describe the ophthalmic phenotype in a cohort of patients with Joubert syndrome for whom the diagnosis was made using current diagnostic criteria.
  
  
  METHODS
  Prospective case series.
  
  
  METHODS
  Eight children diagnosed clinically with radiologic confirmation.
  
  
  METHODS
  Ophthalmic examination and visual electrophysiology.
  
  
  METHODS
  Ocular and oculomotor examination (as allowed by patient cooperation), electroretinography, flash visual-evoked potential (fVEP).
  
  
  RESULTS
  Patients' ages ranged from 7 months to 10 years. Saccadic dysfunction was observed in all cooperative patients (6/6); compensatory head thrusts or turns were present in all except the youngest patient (7 months of age). Most patients (5/8) had primary-position nystagmus (see-saw in 3/5). Abnormal pursuit (3/7) and a dystrophic retinal appearance (3/8) were also seen. One patient had bilateral asymmetric ptosis with unilateral lid elevation during ipsilateral abduction. Electroretinography findings were normal for all 8 patients. Seven patients underwent fVEP; 6 were abnormal (asymmetric) and one was not interpretable because of study artifact.
  
  
  CONCLUSIONS
  Ophthalmologists should be aware that saccadic dysfunction (typically with head thrusts) and primary position nystagmus (typically see-saw) in a developmentally delayed child suggest the diagnosis of Joubert syndrome, especially if a dystrophic retinal appearance is also present. Our findings of asymmetric fVEPs and see-saw nystagmus suggest an abnormality in optic nerve decussation, consistent with the concept that impaired axonal guidance occurs in patients with Joubert syndrome.
  
  
  BACKGROUND
  The author(s) have no proprietary or commercial interest in any materials discussed in this article.
authors.affiliation: Division of Pediatric Ophthalmology, King Khaled Eye Specialist Hospital, Riyadh, Kingdom of Saudi Arabia. arif.khan@mssm.edu
authors.forename: Arif O
authors.initials: AO
authors.lastname: Khan
authors.forename: Darren T
authors.initials: DT
authors.lastname: Oystreck
authors.forename: Mohamed Z
authors.initials: MZ
authors.lastname: Seidahmed
authors.forename: Abdulmajeed
authors.initials: A
authors.lastname: AlDrees
authors.forename: Salah A
authors.initials: SA
authors.lastname: Elmalik
authors.forename: Ibrahim A
authors.initials: IA
authors.lastname: Alorainy
authors.forename: Mustafa A
authors.initials: MA
authors.lastname: Salih
mesh_terms: D001933:Brain Stem / Q000002:abnormalities*; D002531:Cerebellum / Q000002:abnormalities*; D002648:Child; D002675:Child, Preschool; D002658:Developmental Disabilities / Q000175:diagnosis; D004596:Electroretinography; D005074:Evoked Potentials, Visual; D005128:Eye Diseases / Q000175:diagnosis*; D005260:Female; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D009421:Nervous System Malformations / Q000175:diagnosis*; D009759:Nystagmus, Pathologic / Q000175:diagnosis; D015835:Ocular Motility Disorders; D011446:Prospective Studies; D012164:Retinal Diseases / Q000175:diagnosis; D012438:Saccades; D013577:Syndrome