title: Intraocular pressure at a simulated altitude of 9000 m with and without 100% oxygen.
abstract: BACKGROUND
  Exposure to high altitude may affect intraocular pressure (lOP). This study aimed to determine how IOP was altered by two different inspired oxygen tensions at altitude.
  
  
  METHODS
  There were 34 healthy male pilots, ages 26-39 yr (mean 31.9 yr), who were studied at the Air Health Examination and Physiological Training Centre in Eskisehir, Turkey. They were studied at ground level, which is 792 m (2414 ft), and during a training session in a hypobaric chamber at a simulated altitude of 9144 m (30,000 ft). IOP was measured with a Tone-pen XL tonometer before subjects entered the chamber, at altitude while breathing 100% oxygen by mask and after removing the mask, and again 30 min after leaving the chamber.
  
  
  RESULTS
  Ground level values for IOP (mean +/- SD) were 12.31 +/* 2.98 mmHg. Levels increased significantly at altitude on oxygen (16.75 +/- 4.14 mmHg) and decreased slightly on breathing ambient air (14.37 +/- 3.44 mmHg). In 30 min after leaving the chamber, IOP was 12.81 +/- 1.74 mmHg, indistinguishable from pre-test values.
  
  
  CONCLUSIONS
  Healthy subjects whose baseline IOP is in the normal range experience only a small, temporary elevation of IOP during passive exposure to high altitude with either normoxia or acute hypoxia.
authors.affiliation: Department of Ophthalmology, Gulhane Military Medical Academy, Haydarpasa Training Hospital, Kadikoy/Istanbul, Turkey.
authors.forename: Dilaver
authors.initials: D
authors.lastname: Ersanli
authors.forename: Senol
authors.initials: S
authors.lastname: Yildiz
authors.forename: Murat
authors.initials: M
authors.lastname: Sonmez
authors.forename: Ahmet
authors.initials: A
authors.lastname: Akin
authors.forename: Ahmet
authors.initials: A
authors.lastname: Sen
authors.forename: Gunalp
authors.initials: G
authors.lastname: Uzun
mesh_terms: D000328:Adult; D000531:Altitude; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D010100:Oxygen / Q000008:administration & dosage*; D014065:Tonometry, Ocular
chemical_list: D010100:Oxygen