optical

{ } a. [ F. optique, Gr. 'optiko`s; akin to 'o`psis sight, 'o`pwpa I have seen, 'o`psomai I shall see, and to 'o`sse the two eyes, 'o`ps face, L. oculus eye. See Ocular, Eye, and cf. Canopy, Ophthalmia. ] 1. Of, pertaining to, or using vision or sight; as, optical illusions. [ wns=2 ]
Syn. -- ocular, optic, visual. [ 1913 Webster + WordNet 1.5 ]

The moon, whose orb
Through optic glass the Tuscan artist views. Milton. [ 1913 Webster ]

2. Of or pertaining to the eye; ocular; as, the optic nerves (the first pair of cranial nerves) which are distributed to the retina; the optic (or optical) axis of the eye. See Illust. of Brain, and Eye. [ wns=3 ] [ 1913 Webster ]

3. Relating to the science of optics or to devices designed to assist vision; as, optical works; optical equipment. [ wns=1 ] [ 1913 Webster +PJC ]

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. [ 1913 Webster ]