Horopter

The theoretical point horopter (from Greek Horos, "border", and opter, " scouts " ) is the totality of the points which are imaged at a fixed eye position in both eyes at corresponding points of the retina.

Points or objects that lie on the surface of Horopters or at a short distance to the so-called Panumbereich be easily perceived (merged ), such that before ( = crossed lateral disparity ) or behind ( = uncrossed lateral disparity ) are to be seen double (physiological diplopia), but suppresses their concrete perception generally.

If corresponding retinal areas are defined by identical angles from the line of sight of the eye, is the horopter of a circle segment, the Vieth Müller segment that passes through the nodes of the both eyes, and the fixation point and terminates at the optical nodes. The nodes are the points of intersection of the linear connection between the object and its image with the optical axis. Outside the area defined by the nodes and the fixation point of the horopter exists only along an approximately vertical line which extends in the plane bisecting the axis interokuläre and its perpendicular ( mid-sagittal plane). This line is often called the vertical horopter. Outside these two lines there are no points in space, the corresponding (ie, same angle ) retina irritate.

Should the roll angle of the eye to the visual axis ( torsion ) of the two eyes from each other, there is the horopter of two continuous Schraublinien approaching the visual level of up or down from the direction of the vertical Horopters, and then in the direction of the optical nodal points of the eyes to the Vieth -Müller - segment approach.

Empirically soft corresponding points on the definition given above, the angle equality, which leads to deformation of the so-called empirical Horopters compared to the theoretical. Within the visual plane defined by the two nodes and the fixation target, the turning radius of the Horopters changes depending on the distance to the fixation point. There is thereby a fixation distance that abathische distance for which the horopter approximately flat, that is, a straight line within the visual level. For fixations beyond this distance abathischen the horopter is hyperbolic deforms and bends away from the viewer. For fixation closer than the distance abathische the horopter is flatter than the Vieth -Müller segment. After its two discoverers Ewald Hering and Franz Hillebrandt This deviation from the theoretical horopter is called Herring Hillebrandt deviation.

Outside the visual level, the empirical vertical horopter from the observer tends away. This finding can be explained by a shear of the corresponding parts of the retina opposite the angle equality and is named after its discoverer Hermann von Helmholtz Helmholtz shear.

The term horopter itself goes back to the Belgian Jesuit monk Franciscus Aguilonius, who introduced him in the second book of his 1613 published six books on optics than those area, be located in the monocular viewed objects.