{ Op″tic (ŏp″tĭk), Op″tic‐al (–tĭ‐kal), } a. [F. optique, Gr. �; akin to � sight, � I have seen, � I shall see, and to � the two eyes, � face, L. oculus eye. See Ocular, Eye, and cf. Canopy, Ophthalmia.] 1. Of or pertaining to vision or sight.
The moon, whose orb
Through optic glass the Tuscan artist views. Milton.
2. Of or pertaining to the eye; ocular; as, the optic nerves (the first pair of cranial nerves) which are distributed to the retina. See Illust. of Brain, and Eye.
3. Relating to the science of optics; as, optical works.
Optic angle(Opt.), the angle included between the optic axes of the two eyes when directed to the same point; — sometimes called binocular parallax. — Optic axis. (Opt.) (a) A line drawn through the center of the eye perpendicular to its anterior and posterior surfaces. In a normal eye it is in the direction of the optic axis that objects are most distinctly seen. (b) The line in a doubly refracting crystal, in the direction of which no double refraction occurs. A uniaxial crystal has one such line, a biaxial crystal has two. — Optical circle(Opt.), a graduated circle used for the measurement of angles in optical experiments. — Optical square, a surveyor's instrument with reflectors for laying off right angles.