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).
These include ophthalmologists, optometrists, and opticians. An ophthalmologist is a medical doctor specializing in the eye. An optometrist has a doctor of optometry degree and is able to provide full eye care. An optician is not a doctor, but a medical technician specializing in creating eyeglasses and contact lenses. To diagnose and treat eye infections, you would see an ophthalmologist or an optometrist. In addition, an internist or family physician can prescribe antibiotics to treat infections such as conjunctivitis (pinkeye).