Eye (2014) 28, 1328–1333; doi:10.1038/eye.2014.211; published online 5 September 2014 Effects of head elevation on intraocular pressure in healthy subjects: raising bed head vs using multiple pillows
D-Y Yeon1, C Yoo1, T-E Lee2, J-H Park1 and Y Y Kim1
1Department of Ophthalmology, Korea University College of Medicine, Seoul, Korea
2Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University College of Medicine, Seoul, Korea
To evaluate the effects of different methods of head elevation on intraocular pressure (IOP) in healthy young subjects.
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.
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).
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.
Body posture is one of the factors influencing the fluctuation of IOP.10 Compared with the upright posture, IOP has been shown to increase in the horizontal postures (supine,11, 12, 13, 14, 15, 16, 17 prone, or lateral decubitus18, 19, 20, 21, 22, 23, 24) in healthy and glaucomatous eyes. Such posture-induced IOP rise has been associated with progression of glaucomatous damage.21, 22, 25 Some researchers studied the effect of sleeping in a head-up position using a wedge pillow in glaucoma patients26, 27 and healthy subjects,27 and they demonstrated reduction of mean IOP by 1.5–3.2 mm Hg in the head-up position compared with the flat position. However, keeping the head up can be achieved by other methods such as using multiple pillows (MP) or raising the head of the bed.
We conducted this study to investigate the effects of head elevation on IOP in healthy young subjects and compare the two different methods of head elevation in their effects on IOP.
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