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Michael C Brodsky
The perceptual correlates of sensory cyclofusion have received little attention. However, they are easily elicited by asking patients with torsion about perceived slant of the visual world, and by watching how they hold the Titmus or Randot book. Sensory cyclofusion induces two types of perceptual aberrations. First, it rotates the plane of maximal stereoscopic volume in the pitch plane. As such, patients with large degrees of disconjugate binocular torsion can overcome a cyclodisparity by slanting the Titmus book to align the vertical images of the object with those of the retinas...
2002: American Orthoptic Journal
Hiroyuki Mitsudo, Hirohiko Kaneko, Shin'ya Nishida
Mitsudo [Mitsudo, H. (2007). Illusory depth induced by binocular torsional misalignment. Vision Research, 47, 1303-1314] reported a new depth illusion in which a static flat pattern consisting of curved lines appears stereoscopically stratified when viewed with eccentric elevated gaze. He proposed a hypothesis that the illusory depth produced with the curved-line stereogram might originate in a failure to counteract the effect of cyclovergence (i.e., the binocular misalignment of the eyes about the lines of sight)...
February 2009: Vision Research
Hiroyuki Mitsudo
This study reports a new depth illusion in which a static flat pattern appears stratified stereoscopically when viewed binocularly with an elevated gaze. Three psychophysical experiments measured perceived relative depth and fixational cyclodisparity (a rotation of one eye's view relative to the other eye's view about the line of sight) when flat patterns drawn with solid or dashed curved lines were fixated at various levels of gaze elevation. Experiments 1 and 2 showed that the patterns drawn with solid lines produced illusory depth only at large gaze elevations (downward and upward)...
May 2007: Vision Research
Manabu Miyata, Satoshi Hasebe, Hiroshi Ohtsuki, Masayuki Sato
PURPOSE: To evaluate with a synoptophore slant perception induced by binocular cyclodisparities in normal subjects and to argue for the possibility of abnormal slant perception in patients with cyclo-vertical strabismus. METHODS: A vertical line with cyclodisparities that ranged from 0 degrees to +/- 10 degrees was presented to 17 normal subjects (mean +/- SD age, 28.4 +/- 5.6 years; 11 men and 6 women) with a synoptophore, and the perceived slant of the line in the pitch plane was measured by a matching method...
March 2005: Japanese Journal of Ophthalmology
Ananth V Mudgil, Mark Walker, Heimo Steffen, David L Guyton, David S Zee
PURPOSE: We wanted to determine the mechanisms of motor vertical fusion in patients with superior oblique paresis and to correlate these mechanisms with surgical outcomes. METHODS: Ten patients with superior oblique paresis underwent 3-axis, bilateral, scleral search coil eye movement recordings. Eye movements associated with fusion were analyzed. RESULTS: Six patients had decompensated congenital superior oblique paresis and 4 had acquired superior oblique paresis...
June 2002: Journal of AAPOS: the Official Publication of the American Association for Pediatric Ophthalmology and Strabismus
Clifton M Schor, James S Maxwell, Jefrey McCandless, Erich Graf
Vergence eye alignment minimizes horizontal, vertical, and cyclodisparities to optimize stereo-depth perception. Only the horizontal component of vergence is under voluntary control. Couplings with voluntary version and horizontal vergence guide vertical vergence and cyclovergence. Can these couplings be modified in response to sensory demands on binocular vision? We have modified vertical vergence and cyclovergence in response to optical changes in disparity. Vertical vergence was stimulated with aniseikonic lenses that exaggerated vertical disparity in tertiary gaze...
April 2002: Annals of the New York Academy of Sciences
C M Schor, J S Maxwell, E W Graf
Binocular alignment of foveal images is facilitated by cross-couplings of vergence eye movements with distance and direction of gaze. These couplings reduce horizontal, vertical and cyclodisparities at the fovea without using feedback from retinal image disparity. Horizontal vergence is coupled with accommodation. Vertical vergence that aligns tertiary targets in asymmetric convergence is thought to be coupled with convergence and horizontal gaze. Cyclovergence aligns the horizontal retinal meridians during gaze elevation in symmetrical convergence and is coupled with convergence and vertical gaze...
2001: Vision Research
J S Maxwell, E W Graf, C M Schor
The long-term fusion of vertical or horizontal disparities by vergence eye movements is known to evoke persistent changes in vertical and horizontal eye alignment. Adaptive changes in response to torsional disparities have not been well studied. Torsional eye position was measured binocularly with a video system before and after 90 min training periods in which subjects attempted to fuse cyclodisparities. Subjects trained with either a single cyclodisparity presented at a single vertical eye position or with cyclodisparities that varied smoothly from an incyclodisparity to an excyclodisparity as a function of either vertical or horizontal eye position...
December 2001: Vision Research
I T Hooge, A V van den Berg
Cyclovergence is a simultaneously occurring cyclorotation of the two eyes in opposite directions. Cyclovergence can be elicited visually by opposite cyclorotation of the two eyes' images. It also can occur in conjunction with horizontal vergence and vertical version in a stereotyped manner as described by the extended Listing's law (or L2). We manipulated L2-related and visually evoked cyclovergence independently, using stereoscopic images of three-dimensional (3D) scenes. During pursuit in the midsagittal plane, cyclovergence followed L2...
May 2000: Journal of Neurophysiology
J S Maxwell, C M Schor
The coordination of head tilt, ocular counter-roll and vertical vergence is maintained by adaptive mechanisms; the desired outcome being clear single vision. A disruption or imbalance in otolith-ocular pathways may result in diplopia which stimulates these adaptive processes. In the present experiment, dove prisms were used to create cyclodisparities that varied with head tilt about a naso-occipital axis (roll). A stimulus for incyclovergence was presented with the head rolled 45 degrees to one side and a stimulus for an excyclovergence was presented with the head rolled 45 degrees to the other side...
1999: Vision Research
M J Taylor, D C Roberts, D S Zee
PURPOSE: To describe adaptive changes in torsional alignment that follow sustained cyclovergence in healthy humans. METHODS: Eye movements were recorded binocularly from four healthy subjects using dual-coil scleral annuli. Cyclovergence movements were evoked over periods of 30 to 150 seconds using a stereoscopic display, presenting gratings of lines arranged horizontally, vertically, or at 45 degrees, subtending angles of up to 48 degrees. In- and excyclodisparities of 5 degrees were introduced and removed in a single-step fashion...
April 2000: Investigative Ophthalmology & Visual Science
R S Allison, I P Howard, B J Rogers, H Bridge
Linear transformations (shear or scale transformations) of either horizontal or vertical disparity give rise to the percept of slant or inclination. It has been proposed that the percept of slant induced by vertical size disparity, known as Ogle's induced-size effect, and the analogous induced-shear effect, compensate for scale and shear distortions arising from aniseikonia, eccentric viewing, and cyclodisparity. We hypothesised that these linear transformations of vertical disparity are processed more slowly than equivalent transformations of horizontal disparity (horizontal shear and size disparity)...
1998: Perception
D Tweed
When we view objects at various depths, the 3-D rotations of our two eyes are neurally yoked in accordance with a recently discovered geometric rule, here called the binocular extension of Listing's law; or L2. This paper examines the visual and motor consequences of this rule. Although L2 is a generalization of Listing's original, monocular law, it does not follow from current theories of the latter's function, which involve minimizing muscle work or optimizing certain aspects of retinal image flow. This study shows that a new optimization strategy that combines stereo vision with motor efficiency does explain L2, and describes the predictions of this new theory...
July 1997: Vision Research
I P Howard, M Ohmi, L Sun
Several psychophysical procedures have been used to measure cyclovergence but none has been adequately validated with respect to an objective measure. Scleral search coils were used to measure cyclovergence induced by dichoptic textured patterns which cyclorotated in antiphase through 6 degrees at frequencies between 0.05 and 2 Hz. In one psychophysical procedure subjects nulled the apparent oscillatory motion of radial nonius lines superimposed on a small black disc at the center of a large cyclorotating display...
1993: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
I P Howard, J E Zacher
By the use of scleral search coils a continuous record of human cyclovergence was obtained while two identical 80 degrees textured patterns, presented dichoptically, oscillated in the frontal plane in counterphase through 1, 3 and 6 degrees of cyclorotation at frequencies between 0.05 and 2 Hz. The amplitude and gain of the response decreased exponentially with increasing stimulus frequency. As stimulus amplitude increased, response amplitude also increased but gain was highest for low-amplitude cyclorotations...
1991: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
R A Crone, Y Everhard-Hard
Fusional cyclovergence was demonstrated for the first time, using ab objective photographic method. It was discovered that the results of subjective and objective measurements of cyclovergence agreed exactly. The largest fusional cyclovergence observed was 8 degrees. The cyclovergence partly cancels out the cyclodisparity presented. The greater part of the cyclodisparity usually remains. The maximum aplitude of the sensory cyclofusion is of the order of 8 degrees. The cyclovergence response is greatest when large fusion images with numerous horizontal contours are presented...
July 4, 1975: Albrecht Von Graefe's Archive for Clinical and Experimental Ophthalmology
K Hooten, E Myers, R Worrall, L Stark
Static photographic evidence of the occurrence of cyclovergence is presented that supports and extends the result of Crone and Everhard-Halm (1975). Wide-angle complex targets were a necessary condition; simple horizontal line targets were insufficient. Our asymmetrical disparity targets supported in part the conformance of cyclovergence to Hering's Law but raised questions relating to the computational process that also acts to remove cyclodisparity and permits cyclofusion. Saturation and hysteresis nonlinearities were observed...
March 5, 1979: Albrecht Von Graefe's Archive for Clinical and Experimental Ophthalmology
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