Many of us who have experimented with home eye pressure monitoring have noticed unexpected changes in our eye pressure ("IOP") in response to things we do (or even things we think).
One interesting observation is that simply relaxing our facial muscles or releasing the feeling of tension in our eyes (again, by relaxing our muscles) can result in a near instantaneous drop in intraocular pressure ("IOP"). Conversely, we often see that unconsciously holding tension in the area of our eyes or face can lead to increased IOP.
Over the years many vision professionals have expressed skepticism around this observation. It's not part of their clinical experience, so they tend to believe it is not real -- i.e., they assume we patients don't know how to measure our IOP consistently or accurately.
We are sometimes told that stress cannot affect IOP or that being tense does not raise our eye pressure. Our accurate self-tonometry data shows us the opposite -- that these IOP changes related to "tension" can and do happen in a predictable manner.
The human eye has six major extraocular muscles that control movement. When feeling stressed or tense, we can tighten some or all of those muscles, even when not consciously moving our eyes.
Contraction of the extraocular muscles directly compresses the sclera and increases intraocular pressure. Furthermore, contraction of the extraocular muscles inhibits the vortex venous return, thus increasing pressure on the suprascleral venous sinus, obstructing the aqueous humor return, and also increasing intraocular pressure.
The paragraph above explains two ways that tension in the extraocular muscles can change IOP. It comes from the following paper.
On a related note, I have found that self-tonometry is synergistic with relaxation training (including meditation). Self-tonometry can be used as a biofeedback device to help us achieve deeper relaxation, for example. That's discussed in one of the answers here:
What Are Examples of the Different Approaches to Home Eye Pressure Monitoring? | Ask FitEyes