Variations in Intraocular Pressure with Head Position

Intraocular pressure (IOP) is a major modifiable risk factor in glaucoma. Although clinic measurements are typically made in the seated position, patients spend many hours each day (and night) in other postures. Several studies have examined how changes in head and body position—supine, lateral decubitus, neck flexion/extension, head‑up tilt, and simple pillow use—affect IOP. Here we bring together findings from five focused studies.

What the studies show

1. Sitting vs lying flat

IOP is consistently lower when sitting upright compared to lying flat on the back. Lying on one side raises IOP in the lower “dependent” eye [1,5].

2. Head‑down positions

Bending forward or tilting the head down increases IOP further [1,5].

3. Head elevation during sleep

Sleeping with the head and upper body raised (about 30°) lowers IOP compared with lying flat. Raising the whole bed head works better than stacking pillows, which may bend the neck and reduce the effect [2,3].

4. Glaucoma type matters

In open‑angle glaucoma, posture produces moderate changes (a few mmHg). In angle‑closure glaucoma, the pressure rise when lying sideways can be larger (≈5–6 mmHg). This is thought to be linked to crowded eye anatomy [4,5].

5. Magnitude

Small changes (2–4 mmHg) are common, but some patients can see reductions of 20% or more with head‑up sleeping [3].

Limitations 

These studies were small, short‑term, and often involved only healthy volunteers or selected patient groups. They measured IOP changes over minutes to hours, not long‑term disease outcomes. 

Implications

For clinicians: 
- Because IOP rises at night or when lying down, a person’s “true” pressure load may be higher than daytime clinic readings suggest
- It may be worth asking patients about habitual sleeping positions (although recall bias makes this problematic). Often - but not always - the eye that is more severely affected by glaucoma is on the side the patient sleeps on.

For patients:
- Simple lifestyle measures, like sleeping with the head of the bed elevated, are low‑risk and may complement medical therapy to lower night-time IOP in some patients
- It would be worth discussing this with your doctors however, as there are a number of other physiological changes that occur in sleep and the whole picture needs to be considered – not just eye pressure
- Avoiding prolonged head‑down activities.
- Not always sleeping on the same side may also be sensible.

Some Important Caveats

• Glaucoma progression is clearly multifactorial. While nocturnal IOP elevation and posture-related changes in eye pressure are important, they are only part of the story. Peak pressures, 24-hour fluctuations, ocular perfusion factors such as systemic blood pressure and nocturnal hypotension, and the translaminar pressure difference (IOP minus cerebrospinal fluid (CSF) pressure) all influence the optic nerve’s vulnerability. The translaminar concept is particularly compelling: studies suggest that many glaucoma patients, especially those with normal-tension disease, have lower CSF pressure, which amplifies the gradient across the lamina cribrosa even at so-called “normal” IOP levels.
• Both IOP and intracranial pressure (ICP) are posture-dependent — they rise in the supine or head-down position and fall when upright or with head elevation. However, IOP often rises proportionally more than ICP in glaucoma patients, widening the translaminar gradient at night and possibly driving optic nerve damage.
• Simple interventions, such as elevating the head of the bed by 15–30°, can lower both IOP and ICP, but whether this translates into long-term slowing of glaucoma progression remains unproven.

• For now, the message is pragmatic: upright positions lower eye pressure and are protective, lying flat or head-down raises risk. Posture modification is a low-risk adjunct to reduce night-time IOP that may complement traditional therapies — though we still need evidence from larger, long-term studies to determine if there is any benefit for glaucoma control.

  
  References

1. Malihi M, Sit AJ. Effect of Head and Body Position on Intraocular Pressure. Ophthalmology. 2012;119(5):987–991. doi:10.1016/j.ophtha.2011.11.024

2. Yeon DY, Yoo C, Lee TE, Kim YY. Effects of head elevation on intraocular pressure in healthy subjects: raising bed head vs using multiple pillows. Eye. 2014;28(11):1328–1333. doi:10.1038/eye.2014.211

3. Buys YM, Alasbali T, Jin YP, Smith M, Gouws P, Geffen N, Flanagan JG, Shapiro CM, Trope GE. Effect of Sleeping in a Head-Up Position on Intraocular Pressure in Patients with Glaucoma. Ophthalmology. 2010;117(7):1348–1351. doi:10.1016/j.ophtha.2009.11.016

4. Hsia Y, Su CC, Wang TH, Huang JY. Posture-Related Changes of Intraocular Pressure in Patients With Acute Primary Angle Closure. J Glaucoma. 2022;31(12):834–840. doi:10.1097/IJG.0000000000002131

5. Sang Q, Xin C, Yang D, Mu D, Wang N. Effect of Different Postures on Intraocular Pressure in Open-Angle Glaucoma. Ophthalmol Ther. 2024;13(1):149–160. doi:10.1007/s40123-023-00845-3