Two-thirds of patients with glaucoma experienced an intraocular pressure increase when sleeping with their head elevated on two pillows, according to a recent study.
In patients with glaucoma, a high-pillow sleeping posture was associated with higher intraocular pressure (IOP), greater 24-hour intraocular pressure variability, and lower ocular perfusion pressure (OPP) compared with the supine position. Researchers found that among 144 patients, 66.7% (n = 96) of them experienced an increase in IOP when transitioning from the supine to a high-pillow position, with a mean rise of 1.61 ± 1.31 mmHg. Mean IOP was higher in the high-pillow position compared with in the supine position (17.42 ± 4.34 mmHg vs 16.62 ± 3.81 mmHg), while OPP was significantly lower (54.57 ± 8.19 mmHg vs 58.71 ± 8.02 mmHg). The high-pillow posture was also associated with greater 24-hour IOP variability.
In the prospective observational study, the researchers enrolled patients with glaucoma who underwent standardized 24-hour IOP monitoring between October 2023 and April 2024. Eligibility criteria included glaucomatous optic disc damage with corresponding retinal nerve fiber layer thinning, reproducible visual field defects, open anterior chamber angles, and no secondary causes of IOP elevation. Patients with angle-closure glaucoma, ocular trauma, corneal abnormalities affecting measurement accuracy, or inability to cooperate with testing were excluded. The analysis was limited to the right eye of each patient, and participants continued prescribed topical IOP–lowering therapies during monitoring.
IOP was measured every 2 hours using a rebound tonometer. Daytime measurements were obtained in the sitting position, while nighttime assessments were performed after patients retired to bed in a supine position. At each nocturnal time point, IOP was first measured supine and then repeated after 10 minutes in a high-pillow position, defined as a head elevation of approximately 20° to 35° using two standard pillows. Four paired measurements were collected for each posture. OPP was estimated using brachial blood pressure and posture-specific formulas.
“Compared with the supine position, the high-pillow position is associated with elevated IOP, increased 24-hour IOP fluctuation and reduced OPP in glaucoma patients,” noted lead study author Tong Liu, of the Eye Center of the Second Affiliated Hospital at the Zhejiang University School of Medicine and Hangzhou Third People’s Hospital at the Zhejiang Chinese Medical University, and colleagues.
Median postural IOP change was 1.88 mmHg. Larger changes were observed in younger patients and in those with primary open-angle glaucoma compared with normal-tension glaucoma. In multivariable analyses, thicker central corneal thickness and primary open-angle glaucoma independently predicted greater postural IOP fluctuation.
To explore a potential mechanism, the researchers performed jugular vein ultrasonography in 20 healthy volunteers. Compared with the supine position, the high-pillow position was associated with smaller internal and external jugular vein diameters and cross-sectional areas and increased internal jugular vein blood flow velocity.
The researchers noted several limitations. The head elevation angle in the high-pillow position varied and wasn't recorded for patients, introducing variability in exposure. Jugular vein assessments were conducted in healthy volunteers rather than patients with glaucoma. In addition, limited subgroup sample sizes and wide dispersion in postural IOP values resulted in broad confidence intervals, indicating the need for further studies.
The study was funded by the Key Research and Development Program of Zhejiang Province. The study authors reported no conflicts of interest.
