Abstract
Purpose: :
Previous studies have established an increase in intraocular pressure (IOP) when patient position is altered from the upright or standing position to the supine position. In glaucomatous eyes, which may be exquisitely sensitive to even mild elevations in pressure, hours spent in the supine position while sleeping may be a period of increased progression of optic nerve loss. We report an original study assessing whether elevating a patient's upper body from supine to a 45º position results in an appreciable decrease in IOP.
Methods: :
A total of 64 male and female patients (mean age 59.3) subdivided into groups with and without glaucoma were enrolled in the study. A Tonopen was used to measure the intraocular pressures. IOP was first measured while the subjects were seated in the upright position in the standard exam chair. They were then placed at 180º in the supine position for 10 minutes, after which the IOP was recorded again. The chair was then elevated to 45º, and after 10 minutes in this third position, the pressure was recorded once more. At each position, the intraocular pressure was measured sequentially three times in each eye, and an average was recorded. The average difference in IOP between all positional changes was then calculated.
Results: :
The mean intraocular pressure change when elevated to the 45º position for the right eye in glaucomatous patients, non-glaucomatous patients and the total group decreased 1.89 mm Hg(11.8%), 1.0 mm Hg(6.8%) and 1.32mmHg(8.8%) respectively as compared to the supine position. In the left eye, the mean intraocular pressure decreased an average of 1.46 mm Hg (9.7%) for glaucomatous patients, 1.7 mm Hg(10.9%) for non-glaucomatous patients and 1.65 mm Hg (10.8%) for the total group
Conclusions: :
Body position effects intraocular pressure. Our study revealed a difference in IOP in both glaucomatous and normal eyes when a patient’s upper body is elevated from supine to a 45º position. We suggest that potential benefit may arise from having patient with glaucoma sleep in the 45º position. It may prove to be an effective, inexpensive and non-invasive adjunct in IOP reduction for daily glaucoma care.
Keywords: intraocular pressure • optic nerve • outflow: trabecular meshwork