Elevated sleeping position lowers nocturnal IOP

The authors conducted this study to determine whether a 30-degree head-up sleeping position decreases nocturnal IOP in patients with glaucoma compared with lying flat. They hypothesized that patients with progressive glaucoma, despite low IOP during office hours, may have a postural IOP response contributing to progression, and that raising the head of the bed when sleeping may significantly decrease this response and improve disease control.

Because disc hemorrhages have been associated with glaucoma progression, the authors conducted the study in 17 patients (17 eyes) with a new disc hemorrhage and IOP in the teens. They were evaluated in a sleep laboratory on two separate nights, the first night lying flat and the second night in a 30-degree head-up position. IOP and blood pressure were measured every 2 hours from 6 p.m. to 8 a.m. For the 6 p.m., 8 p.m., 10 p.m. and 8 a.m. measurements (awake period), subjects were sitting for both nights. For the midnight, 2 a.m., 4 a.m. and 6 a.m. measurements (sleep period), they were supine for the first night and 30 degrees head up for the second night.

There were no significant differences in IOP between the two study visits during the awake period when patients were sitting upright. During the sleep period, the mean IOP was 3.2 mmHg lower in the 30-degree head-up position compared with the flat position (P = 0.03). Sixteen of 17 patients (94.1 percent) had lower IOP in the 30-degree head-up position. The reduction in IOP was 20 percent or more in 35 percent of patients (6/17). There were no differences in blood pressure or ocular perfusion pressure between the two positions.

The authors said the results suggest that physicians should not ignore nighttime pressure increases that occur when glaucoma patients sleep in the flat position. They conclude that clinicians should consider recommending simple postural changes to patients with features of progressive glaucoma despite good IOP during office hours. However, they note that further studies are required to prove whether such postural changes help prevent glaucoma progression.