The symptoms you have described could be due to surface issue and your tear film stability. Get it checked with your local ophthalmologist. Any history of injury to the eye which has larger pupil , are the pupillary size differing in light and dark illumination, do you have drooping of eye lids, any pilocarpine test done by your ophthalmologist?? In short, it can be physiological or neurological. See a neuroophthalmologist in your city.