Long-term factors: corneal thickness, heredity, age, gender, race, eye hardness, refractive error, etc. Transient factors: eye pressure, body position such as lying down, head down, etc., tense movement, musical instrument playing, etc. can raise IOP; tie, shirt button too tight, breath holding can also raise IOP. Drinking large amounts of water at one time can also cause a transient increase in intraocular pressure. Other factors: drugs, alcohol, smoking, etc.