optometryMeasurement of the acuity of vision and the degree of lens correction required to restore "normal vision" in subjects with refractive errors (myopia; hyperopia; astigmatism). Its principal instrument is a chart of letters which subtend specific angles to the eye at a given distance; temporary lenses being used to correct each eye. Related category• HEALTH AND DISEASEAlso on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History |