word-forming element meaning "within, inside, on the inside," from Latin preposition intra "on the inside, within, in, into;" of time, "during, in the course of," related to inter "between," from PIE *en-t(e)ro-, from root *en "in." Commonly opposed to extra-, and compare inter-. The use of intra as a prefix was rare in classical Latin.
c. 1500, "of or pertaining to the eye," from Late Latin ocularis "of the eyes," from Latin oculus "an eye," from PIE root *okw- "to see." As a noun, "eyepiece of an optical instrument," 1835, from the adjective.
<a href="https://www.etymonline.com/word/intra-ocular">Etymology of intra-ocular by etymonline</a>
Harper, D. (n.d.). Etymology of intra-ocular. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/intra-ocular