Hi Alex,
Dilatation of the pupil, also called mydriasis in medical terms,can be due to different cause, like too much norepinephrine, or blockage of the acetylcholine action, or increased intracranial pressure, ans so on. You can check at
https://en.wikipedia.org/wiki/Mydriasis for more details.
Do you have headaches, and do you have discomfort or pain in the eyes as soon as there is bright or moderate bright light, like outdoor on a sunny day ? This last symptom is called "photophobia", see
https://en.wikipedia.org/wiki/Photophobia , and is caused by too much light entering the eye, like when the pupil is too dilated.
We know that POIS brings, in some sufferer if not all, certain symptoms of imbalance of the autonomous nervous system. In your case, it seems to manifest more as a pupil dilatation problem. In my case, it manifest as low blood pressure ( hypotension), another manifestation of autonomous system imbalance.
I suggest you consult an eye specialist, because some investigation could be done to find the exact cause in your case. Also, if judged appropriate by the physician, some drops can be prescribed ( miotic eyedrops like pilocarpine), that can reduce the size of the pupil, by inducing miosis ( pupil contraction, which is the opposite of mydriasis).
In general, I suggest you avoid coffee or other stimulants, like energy drink, since they can cause mydriasis.
Anything that help raise acetylcholine can help to contract the pupil, so adding lecithin in your diet could help, and surely not worsen the condition. Lecithin supplements, or eggs, are good sources of choline. Incidentally, some members report less POIS symptoms with daily eggs consumption.
I hope this will help you elaborate a strategy to help control your mydriasis problem.
