n. 1. (Med.) Measurement of the range of vision, esp. by means of the optometer. [ Webster 1913 Suppl. ] 2. As defined (with minor variations) in the statutes of various States of the United States: (a) “The employment of subjective and objective mechanical means to determine the accomodative and refractive states of the eye and the scope of its function in general.” (b) “The employment of any means, other than the use of drugs, for the measurement of the powers of vision and adaptation of lenses for the aid thereof.” [ Webster 1913 Suppl. ] | 