The word is a modern scientific compound, built transparently from classical components. The prefix "sub-" derives directly from the Latin preposition sub, meaning "under," a stable element inherited from Proto-Indo-European upó. The base "retinal" originates from the Medieval Latin retina, itself likely from the Latin phrase rēte tunica ("net-like tunic"), describing the membrane's appearance. The suffix "-al," from Latin -ālis, denotes pertaining to. Thus, the term's formation follows a straightforward anatomical logic: "sub-retinal" literally describes a position beneath the net-like layer of the eye, a meaning perfectly preserved in its precise medical usage.

Structure: sub (under) + retinal (pertaining to the retina) - sub: A prefix of Latin origin, meaning "under, below, beneath." It functions as a locative modifier. - retinal: An adjective-forming suffix of Latin/Greek origin (from retina + -al), meaning "pertaining to or relating to the retina." It functions as the core substantive element.