In a new study published in Ophthalmology Glaucoma, investigators evaluated intraocular pressure (IOP) behavior after inducing psychological stress in patients diagnosed with primary open-angle glaucoma (POAG).
Give me some background first.
While treatments for glaucoma typically involve reducing IOP, previous research has also shown that stress—without the presence of glaucoma—can elevate IOP levels.
Which led to: Researchers sought to investigate the relationship between IOP and psychological stress.
Now, talk about the study.
Researchers conducted a randomized-controlled trial (RCT) in which participants were selected to undergo the Trier Social Stress Test (TSST) or join a control group.
Who was included in the study?
A total of 39 participants with POAG comprised of:
- 18 individuals in the stress group
- 21 controls
How was it conducted?
The researchers submitted all participants to a modified diurnal tension curve (DTC):
- 1 to 4 weeks before randomization
- During which three IOP measurements were performed between 8 am and 2 pm
Responses to TSST were evaluated by measuring levels of:
- Salivary cortisol
- Salivary amylase
- IOP
- Mean arterial pressure and heart rate
- before, immediately after, and 40 minutes following the TSST
They then applied the State-Trait Anxiety Inventory (STAI) to evaluate levels of anxiety at the same time intervals (listed above).
What were the main outcome measures?
- Changes in IOP (mmHg)
- Salivary cortisol and amylase
- Heart rate
- Mean arterial pressure and STAI scores
Findings?
At baseline, there were no significant differences between groups in terms of:
- Age (P=0.661)
- Gender (P=0.669)
- Salivary cortisol (P=0.104)
- Mean DTC IOP for the right (P=0.439) and left (P=0.576) eyes
When comparing IOP measurements obtained during the DTC and immediately after TSST, a significant mean IOP increase was observed:
- 3.8 mmHg (right eye, P<0.001)
- 4.1mmHg (left eye, P<0.001)
Tell me more.
The following also increased significantly after the TSST:
- Salivary cortisol
- 5.9 nmol/L, P=0.004
- Salivary amylase
- 323,388 UL, P=0.004
- Mean arterial pressure
- 10.1mmHg, P<0.001
- Heart rate
- 12.9bpm, P<0.001
Limitations?
The effect of chronic stress and its relationship with anxiety disorders was not evaluated.
Additionally, investigators did not evaluate if IOP elevation was sufficient to cause glaucoma progression.
Anything else?
The study had a small sample size, which limited the ability to perform a multivariable regression.
What this means: They were unable to evaluate the correlation between variables such as cortisol and age.
For a full overview of the limitations, see the study.
Expert opinion?
The authors stated, “We believe that repetitive stress stimuli in POAG may compromise IOP control and potentially increase the risk of disease progression.”