Abnormal, harmful, or undesirable effect on an organism that causes anatomical or functional damage, irreversible physical changes, or increases the susceptibility to other biological, chemical, or environmental stresses.
Optometrists can prescribe glasses, contact lenses, eye exercises, vision aids and therapy, and (in some states) oral and topical medications to treat certain eye diseases. Ophthalmologists are doctors of the eye. They have graduated from medical school and are licensed to practice medicine, so their credentials are either doctor of medicine (MD) or doctor of osteopathy (DO).
Psychiatrist can prescribe medication. Psychologists are for talking to about your problems and trying to find a way to work through them. Psychiatrist talk with people too but they talk with people that have problems that need medication to be able to cope!!~~~~~~~~~~~~~~~~~~~~~~~~~~~~.