title: Normal-tension glaucoma is associated with sleep apnea syndrome.
abstract: BACKGROUND
  In normal-tension glaucoma, optic nerve damage occurs without elevated intraocular pressures, hence vascular and pathogenic mechanisms other than intraocular pressure effects have been postulated. However, the exact cause(s) remain unknown. We have looked for an association between normal-tension glaucoma and sleep apnea syndrome, a disease characterized by repetitive upper airway obstructions during sleep, inducing hypoxia and sleep disruption with the risk of late cardiovascular and neurological sequelae.
  
  
  METHODS
  We performed overnight polysomnography in 16 consecutive Caucasian patients with normal-tension glaucoma. The respiratory disturbance index (RDI) during night sleep was used to diagnose and grade obstructive sleep apnea. Patients with an RDI of 10 or more were diagnosed as having obstructive sleep apnea.
  
  
  RESULTS
  We observed the following prevalences of obstructive sleep apnea in normal-tension glaucoma patients: 0% (0 of 2) for the group of patients younger than 45 years, 50% (3 of 6) for the age group 45-64 years, and 63% (5 of 8) for the group older than 64 years. Prevalences in the middle and older age group were significantly higher than in a historic control group (p < 0.025 for both, binomial test).
  
  
  CONCLUSIONS
  Normal-tension glaucoma patients constitute a high-risk population for sleep apnea syndrome. Therefore, they should be screened for sleep apnea syndrome, and, if necessary, be treated to avoid late cardiovascular and neurological sequelae.
authors.affiliation: Department of Neuro-Ophthalmology and Strabismus, Kantonsspital St. Gallen, Switzerland. daniel.mojon@kssg.ch
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Mojon
authors.forename: Christian W
authors.initials: CW
authors.lastname: Hess
authors.forename: David
authors.initials: D
authors.lastname: Goldblum
authors.forename: Matthias
authors.initials: M
authors.lastname: Boehnke
authors.forename: Fritz
authors.initials: F
authors.lastname: Koerner
authors.forename: Matthias
authors.initials: M
authors.lastname: Gugger
authors.forename: Claudio
authors.initials: C
authors.lastname: Bassetti
authors.forename: Johannes
authors.initials: J
authors.lastname: Mathis
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005902:Glaucoma, Open-Angle / Q000209:etiology*; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D015995:Prevalence; D020181:Sleep Apnea, Obstructive / Q000150:complications* / Q000175:diagnosis