A recent study published in Ophthalmology and Therapy investigated the relationship of different body positions and postures and their effect on intraocular pressure (IOP).
Give me some background first.
Fluctuations in IOP levels can be an independent risk factor for open-angle glaucoma (OAG)— with some daily activities and postures affecting these levels.
Thus, researchers investigated these different positions and their association with these fluctuations.
Now talk about the study.
This observational study consisted of 74 participants (148 eyes) diagnosed with OAG. All participants had previously visited the outpatient department of Beijing Tongren Hospital between January 2022 and March 2023.
IOP measurements were collected at eight different positions, including:
- Supine
- Left lateral decubitus (laying on left side)
- Right lateral decubitus (laying on right side)
- Head tilted downwards position with immediate head-up
- Seated position
- Seated with head tilted downward
- Standing position
- Walking
Go on…
IOP measurements were taken using the Icare tonometer (Icare PRO; Icare Finland Oy).
Each participant held the position for 5 minutes before measurement occurred and 5-min breaks were taken between each different posture.
Tell me more.
Between 9 AM and 11 AM, six measurements were recorded and averaged for time points. SPSS26.0 (IBM) software was then utilized for statistical analysis.
Each investigated position was compared to the seated position with eyes ahead—as this is the position in which routine clinical IOP measurements are taken.
Findings?
The following positions were statistically associated (p < 0.001) with higher IOP compared to seated with eyes ahead:
- Supine position
- Left lateral decubitus position
- Right lateral decubitus position
- Head-lowered position
Did any positions lead to lower IOP?
Standing and walking were the two positions to exhibit lower IOP levels (p < 0.08, p < 0.001, respectively).
What does this mean?
Overall, the researchers found that the more elevated a position, the lower the IOP observed. The authors theorized this to be due to gravitational fluids impacting pressure.
They maintained that, “The reduction in gravitational potential energy associated with the drainage of aqueous humor into the heart might contribute to the elevation of IOP.”
Expert opinion?
Per the authors, “The observed variations in IOP with different body positions, as found in this study, offer valuable guidance for patients with glaucoma.”
They added that patients who have elevated nighttime IOP and often sleep in lateral positions would potentially benefit from changing to a supine sleeping position.
What else?
The authors suggested that it may be beneficial in those with high IOP to limit time spent in a lateral position during the day and increase time spent walking or engaging in physical activity.
They also recommended limiting the head tilted down position, a position noted to be increasingly common due to mobile phone and computer use.
Take home.
This study identifies key connections between body positions and IOP that can be used by those with OAG to hopefully limit fluctuations.
Further research is needed to determine how age impacts these trends, as well as to include both additional relevant factors and follow-up.