{ ‖ } n. [ NL. optocoelia, fr. Gr. &unr_; optic + koi^los a hollow. ] (Anat.) The cavity of one of the optic lobes of the brain in many animals. B. G. Wilder. [ 1913 Webster ]

n. [ Optic + -gram: cf. F. optogramme. ] (Physiol.) An image of external objects fixed on the retina by the photochemical action of light on the visual purple. See Optography. [ 1913 Webster ]

n. [ Optic + -graphy. ] (Physiol.) The production of an optogram on the retina by the photochemical action of light on the visual purple; the fixation of an image in the eye. The object so photographed shows white on a purple or red background. See Visual purple, under Visual. [ 1913 Webster ]

n. [ Optic + -meter. ] (Physiol.) An instrument for measuring the distance of distinct vision, mainly for the selection of eveglasses. [ 1913 Webster ]

n. One who is skilled in or practices optometry, especially one who examines the eyes for defects in vision and prescribes the proper lenses to correct any defects discovered. [ Webster 1913 Suppl. +PJC ]

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. ]