Controlling glaucoma during sleep

Intraocular pressure (IOP) is the only modifiable risk factor for glaucoma. Previous studies have shown that IOP increases in the supine position as compared to the sitting position. This suggests that it might be beneficial for patients with glaucoma to sit rather than to lie.

However, as it is unreasonable to expect patients to sleep upright, a group of researchers at the University of Toronto, including Tariq Alasbali from the King Faisal University in Saudi Arabia, studied the effect on IOP of sleeping flat as compared to a 30° head-up position. Seventeen patients with glaucoma were studied over two nights. On the first night they slept lying flat, and on the second night a wedge pillow was used to elevate the head at a 30° angle. The IOP was measured every 2 h throughout each night.

The researchers found a significant reduction in IOP when patients were sleeping with the head raised. The effect varied from person to person; however, one-third of the patients had a 20% reduction in IOP in the 30° head-up position. There was no significant difference in blood pressure between the two positions.

There are several limitations to the study, including the small number of subjects and the inability to measure intracranial pressure, which might play a role in glaucoma through the impact on the translaminar pressure gradient. However, the study might help to understand the possible role in glaucoma of the head position during sleep. To date, no other technique has been proposed to reduce the IOP increase when laying flat.

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