optic nerve pathways The course of the chemical and electrical impulse from light stimulating the retina as it passes from the optic nerve to the vision center of the brain. The left and right branches of the optic nerves join behind the eyes, just in front of the pituitary gland, to form a cross-shaped structure…
optic neuroma A rare benign tumor of the optic nerve.
optician A specialist in fitting eyeglasses and making lenses to correct vision problems. An optometrist performs eye examinations and writes prescriptions for corrective lenses; an optician fills that prescription.
optometrist A practitioner who provides primary eye and vision care, performs eye examinations to detect vision problems, and prescribes corrective lenses to correct those problems. Some optometrists also make and fit eyeglasses, but many leave that job to opticians. An optometrist is a doctor of optometry (OD), not an MD. When an optometrist detects eye…
OPV Oral polio vaccine. See polio vaccine, oral.
OR Operating room.
oral Having to do with the mouth. For example, an oral solution is a solution that is given by mouth.
oral cancer Cancer within the mouth. Oral cancer is associated with smoking cigarettes and cigars as well as chewing tobacco. It is generally noticed as a painless growth on the inner cheek, gum, or tongue. Treatment options include surgical resection, radiation, and/or chemotherapy.
oral contraceptive A birth control pill taken by mouth. Most oral contraceptives include both estrogen and progestogen. When given in certain amounts and at certain times in the menstrual cycle, these hormones prevent the ovary from releasing an egg for fertilization. Colloquially known as “the pill.” See also birth control; contraceptive.
oral rehydration solution A specially designed liquid that contains water, glucose, and electrolytes and is given to treat dehydration. Abbreviated ORS.
oral rehydration therapy The administration of special fluids by mouth to treat dehydration. Abbreviated ORT. See also oral rehydration solution.
oral surgeon A dentist who has special training in surgery to correct problems of the mouth and jaw.