horopter

The sum of the points in space, the images of which for a given fixation point fall on corresponding retinal points. If the fixation point is 2 m., the h. is a straight line; if less, a curve concave to the face; if more, a convex curve. [G. horos, limit, + opter, spy, scout, fr. orao, fut. opsomai, to see]

- empirical h. an experimentally determined ellipse passing through the optical centers of two eyes by which points adjacent to the point of fixation, both lying on the ellipse, are perceived to be stimulating corresponding retinal points.

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ho·rop·ter hə-'räp-tər, hȯ- n the locus of points in external space whose images are formed on corresponding places of the two retinas and which are seen single

hor·op·ter·ic .hȯ-.räp-'ter-ik adj

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ho·rop·ter (ho-ropґtər) [Gr. horos limit + optēr observer] the sum of all the spatial points whose images at a given distance fall on corresponding points of the retina. If the point of fixation is 2 meters, the horopter is a straight line across the observer's front (the apparent frontoparallel plane h.); if the point of fixation is less than 2 meters, the horopter is a curve concave to the observer (concave h.); and if the point of fixation is more than 2 meters, the horopter is a curve convex to the observer (convex h.). horopteric adj