optic disk vs optic disc

optic disk and optic disc both are nouns.

Word	Noun	Adjective	Verb	Adverb
optic disk	Yes	No	No	No
optic disc	Yes	No	No	No

As nouns, optic disk and optic disc are synonyms defined as:

optic disk and optic disc: the point where the optic nerve enters the retina; not sensitive to light

Other synonyms of optic disk include blind spot.

optic disk (noun)	optic disc (noun)
the point where the optic nerve enters the retina; not sensitive to light	the point where the optic nerve enters the retina; not sensitive to light