What does epipolic mean?
Epipolic is a rare technical adjective used to describe something relating to the epipole — the precise point where the visual axis, the straight line from the object of regard through the eye's optical centre, meets the surface of the retina. In practical terms, an epipolic image or sensation is one formed at the centre of gaze rather than at the periphery, so the term overlaps closely with what modern science calls foveal or central vision. The word belongs almost entirely to historical and specialist writing: nineteenth- and early twentieth-century works on optics and the physiology of sight employed it when distinguishing direct vision from indirect or collateral vision, and it has since been largely displaced by more familiar terminology. Because of this narrow provenance, readers will encounter epipolic mainly in older scientific texts, and writers today would use it only deliberately, for archaic or scholarly effect.
adjectiveRelating to the epipole, the point on the retina where the visual axis meets its surface; in older optics, pertaining to direct or central vision as opposed to peripheral sight.
- Pertaining to the point on the retina struck by the visual axis; relating to central or direct vision.
"The researcher noted that colours appear most vividly at the epipolic centre of the retina."
"Objects seen directly are imaged upon the epipolic region of the retina."
"His treatise distinguished epipolic from collateral vision with admirable clarity."
Before 'fovea' became fashionable, scientists spoke of the epipolic point — the tiny spot where your line of sight actually lands on the retina.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of epipolic
Epipolic derives ultimately from Greek: the root noun epipolē referred to the point where sight falls upon the eye, formed from epi- ('upon') plus a stem related to vision. English naturalized the adjective in scientific writing on optics, pairing it with the related nouns epipole and epipolia. Its closest relatives in English are therefore other learned terms of Greek origin describing sight and the eye rather than everyday vocabulary.
Related word forms
How epipolic is actually used
A rare, highly technical term found chiefly in historical treatments of optics and physiology of vision; modern literature prefers 'foveal' or 'central'. It carries no figurative or informal usage.
Easily confused with epipolic
Apoplectic means extremely angry or relating to a stroke, whereas epipolic is a technical term for central vision at the retina.