I took my Icare tonometer with me during a flight. Even though it might be considered an "electronic device", the crew was nice enough to allow me to use it even during takeoff and landing. So I collected a nice set of IOP data.
On a short flight (about 2.5 hours), my IOP increased about 5 mm Hg at altitude and then came back down to the baseline IOP upon landing.
I've been flying all my life. My father was a pilot and I have a pilot's license too. So I am fairly sure the change in IOP was not due to being nervous about flying -- I'm very comfortable in an airplane.
It seemed like the change in cabin pressure was correlated with a change in my IOP. I used an Icare TA01i tonometer to take measurements frequently throughout the whole flight. My IOP went up after I felt the pressure change in my ears. And my IOP came back down after that same point at the end of the flight, but it took a few minutes before my IOP was completely back at the baseline. By the time I deplaned and sat down in a seat in the terminal, my IOP was equal to the level before takeoff.
In the following video, the doctor expresses the [incorrect] opinion that IOP will not change during flight because the aircraft cabin is pressurized.
What happens to intraocular pressure at high altitude? - Dr. Sriram Ramalingam
However, we do know that there is a pressure change during flight because we can feel it in our ears. Plus I actually did the experiment instead of theorizing. IOP can increase even in a pressurized cabin.
Responding to some of your comments:
... a short drive from the airport to home so I don't think driving was a factor.
The drive certainly could affect your IOP... many things affect IOP and IOP changes by the minute. Sometimes those changes are small, and not meaningful. But it helps to think of IOP as dynamic.
I took my measurement on my Reichert 7CR within an hour of landing and noticed a spike.
After an hour post-landing, I would have expected your IOP to be normal. However, it is possible that your IOP requires more time to return to normal. I'm not finding clear answers (that are applicable to your situation) regarding the time required for IOP to return to baseline in the published literature.
You might want to edit your question and add more information: how much longer before it returned to baseline? Does flying make you anxious? Did you drink water? How much? (Flying can cause dehydration.)
For reference, see:
What happens to intraocular pressure at high altitude? - PubMed
Results: IOP increased significantly from baseline after acute exposure to altitude before returning to baseline with time.
Conclusions: Acute exposure to altitude caused a statistically significant but clinically insignificant increase in IOP.
If you run across this study, beware of its potentially flawed methodology.
Effect of High Altitude Exposure on Intraocular Pressure Using Goldmann Applanation Tonometry - PubMed