op·ti·cal
/ˈɒptɪkəl/ Show Spelled[op-ti-kuhl] Show IPA
adjective
1.
of, pertaining to, or applying optics or the principles of optics.
2.
constructed to assist sight or to correct defects in vision.
3.
of or pertaining to sight or vision; visual.
4.
of or pertaining to the eye.
http://dictionary.reference.com/browse/optical
vis·u·al
/ˈvɪʒuəl/ Show Spelled[vizh-oo-uhl] Show IPA
adjective
1.
of or pertaining to seeing or sight: a visual image.
2.
used in seeing: the visual sense.
3.
optical.
4.
perceptible by the sense of sight; visible: a visual beauty.
5.
perceptible by the mind; of the nature of a mental vision: a visual impression captured in a line of verse.
http://dictionary.reference.com/browse/visual