title: Effects of head elevation on intraocular pressure in healthy subjects: raising bed head vs using multiple pillows.
abstract: OBJECTIVE
  To evaluate the effects of different methods of head elevation on intraocular pressure (IOP) in healthy young subjects.
  
  
  METHODS
  Twenty-four healthy young Korean subjects were included in this prospective observational study. The IOP measurements were taken with the subjects in the sitting position and in the supine positions with the head flat and 30° up using two different methods: (1) raising the bed head and (2) using multiple pillows. IOP was measured using Tonopen AVIA in both eyes 10 min after assuming each position in a randomized sequence. The Wilcoxon signed-rank test was used to compare the IOP by changing the methods of head elevation.
  
  
  RESULTS
  Mean IOP of both eyes when sitting was lower than that measured in the supine position with head flat (P=0.001). Compared with that measured in the supine position with head flat, the mean IOP was lower when measured in the supine position with the head kept 30 ° up by bed head elevation (P=0.001), whereas the mean IOP was not significantly different when measured in the supine position with the head elevated using multiple pillows (right eye, P=0.061; left eye, P=0.089).
  
  
  CONCLUSIONS
  In normal subjects, IOP was lower when measured in the supine position with the head kept up by the bed head elevation compared with that measured when lying flat. However, such head-up position-induced IOP reduction was not found when the head was kept up using multiple pillows. These findings suggest that elevating the head using multiple pillows may not help to reduce IOP in the supine posture.
authors.affiliation: Department of Ophthalmology, Korea University College of Medicine, Seoul, Korea.
authors.forename: D-Y
authors.initials: DY
authors.lastname: Yeon
authors.affiliation: Department of Ophthalmology, Korea University College of Medicine, Seoul, Korea.
authors.forename: C
authors.initials: C
authors.lastname: Yoo
authors.affiliation: Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University College of Medicine, Seoul, Korea.
authors.forename: T-E
authors.initials: TE
authors.lastname: Lee
authors.affiliation: Department of Ophthalmology, Korea University College of Medicine, Seoul, Korea.
authors.forename: J-H
authors.initials: JH
authors.lastname: Park
authors.affiliation: Department of Ophthalmology, Korea University College of Medicine, Seoul, Korea.
authors.forename: Y Y
authors.initials: YY
authors.lastname: Kim
mesh_terms: D000328:Adult; D001513:Beds; D005260:Female; D006257:Head; D064368:Healthy Volunteers; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D011187:Posture / Q000502:physiology*; D011446:Prospective Studies; D014065:Tonometry, Ocular