horopter

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Related to horopters: empirical horopter, Vieth-Muller circle

horopter

 [hor-op´ter]
the sum of all points seen in binocular vision with the eyes fixed.

ho·rop·ter

(hō-rop'tĕr),
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 horopter is a straight line; if less, a curve concave to the face; if more, a convex curve.
[G. horos, limit, + optēr, spy, scout, fr. oraō, fut. opsomai, to see]

horopter

/ho·rop·ter/ (hor-op´ter) the sum of all points seen in binocular vision with the eyes fixed.

horopter

The locus of object points in space that stimulate corresponding retinal points of the two eyes when the eyes are fixating binocularly one of these object points. The horopter is a curve that passes through the fixation point and changes shape with fixation distance. Objects closer to the eyes than the horopter are seen double (crossed disparity) and objects further than the horopter are seen double (uncrossed disparity). There are various types of horopters depending upon the method of determination. See Panum's area; Fig. D2.
apparent frontoparallel plane horopter 
The locus of object points in space which appear to the observer to lie on a plane through the fixation point, parallel to the plane of the face. Syn. frontal plane horopter. See Hering-Hillebrand deviation; apparent frontoparallel plane.
empirical horopter A horopter determined experimentally by having an observer judge a series of targets to be neither 'nearer than' nor 'farther than' the fixation point. Examples: the frontoparallel plane horopter; the nonius horopter.
longitudinal horopter Horopter that is plotted by only considering the longitudinal section where the rods meet the plane of fixation. Thus this horopter is a curve located in that plane and not a surface.
nonius horopter Horopter plotted by fixating binocularly a central vertical rod while the other rods located in the periphery have their upper halves seen by one eye only and their lower halves seen by the other eye only. Each rod is moved individually until the two halves are seen aligned. Syn. vernier horopter.
rectilinear horopter The assemblage of all lines in space that stimulate corresponding retinal lines. It is a pencil of quadratric surfaces with the space horopter as their common curve of intersection.
space horopter The horopter consisting of all object points in space which stimulate corresponding retinal points as distinguished from the two-dimensional cases such as the apparent frontoparallel plane, longitudinal or nonius horopters.
theoretical horopter A horopter based on theoretical concepts. Example: the Vieth-Müller horopter.
vernier horopter See nonius horopter.
Vieth-Müller horopter A theoretical horopter formed by a circle passing through the point of fixation and the anterior nodal points of the two eyes. Thus any point on this horopter forms an image in the two retinas, which is at equal distances from their respective foveas. Syn. Vieth-Müller circle. See Hering-Hillebrand deviation.