Ive read of a lot of different eyes. Most of the time they are talking about a spiritual eye but in at least one case someone writes about a regular eye gaining the ability of a spiritual eye (eye of truth, wisdom, the celestial eye etc). There are as far as I know no writings of changing literal shape. but its not as though any of these writings had a physical description of the eyes in question . If I spend way too much time on it I can manipulate the pupils shape just a tiny bit. But I dont think its useful in anyway cept maybe to make a staring contest more interesting. If the color change you are getting is from blood vessels then stop trying to do that. Of all the usually autonomous functions of the body you could teach yourself to manipulate. Ocular pressure wouldnt seem to be the most terribly useful.
