added stress can cause fluctuations in brain chemistry which could cause immediate onset as well.do seizure patients or Parkensons patients ever experience any eye abnormalities? or are predisposed to have any eye conditions, sorta like diabetes patients are prone to glaucoma.a chemical imbalance in the brain, (as in bipolar or manic-dep. patients) would cause a great deal of misfiring... which when it comes to brains can effectively cause enigma syndrome in humans and other animals... though the eye-sight doesn't generally change too much.