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George T Manilla, Joe de Braga
Pediatricians and educators may interact daily with several dyslexic patients or students. One dyslexic author accidently developed a personal, effective, corrective reading method. Its effectiveness was evaluated in 3 schools. One school utilized 8 demonstration special education students. Over 3 months, one student grew one third year, 3 grew 1 year, and 4 grew 2 years. In another school, 6 sixth-, seventh-, and eighth-grade classroom teachers followed 45 treated dyslexic students. They all excelled and progressed beyond their classroom peers in 4 months...
2017: Global Pediatric Health
Kristina Irsch, David L Guyton, Hee-Jung S Park, Howard S Ying
PURPOSE: To determine the mechanisms of vertical fusional vergence in patients with "congenital unilateral superior oblique paresis" (SOP) and to discuss the implications of these mechanisms. METHODS: Eleven patients were examined with our eye-tracking haploscope. RESULTS: Three different fusion mechanisms were found, producing significantly different cyclovergence to vertical vergence ratios (P < 0.05): primary use of the vertical rectus muscles in seven patients (ratio: 0...
August 2015: Investigative Ophthalmology & Visual Science
Philip M Grove, Hiroshi Ono
O'Shea and Crassini (1982, Perception & Psychophysics 32 195-196) demonstrated that fusion persists for vertical lines with an orientation disparity of 8 degrees, but diplopia is experienced in simultaneously presented horizontal lines with the same disparity. They concluded that the neural fusion process fuses larger horizontal disparities than vertical disparities. Kertesz criticised their demonstration because it did not quantify the possible motor component associated with fusing their counter-rotated images...
2012: Perception
Julie M Harris, Adrien Chopin, Katharina Zeiner, Paul B Hibbard
Given an estimate of the binocular disparity between a pair of points and an estimate of the viewing distance, or knowledge of eye position, it should be possible to obtain an estimate of their depth separation. Here we show that, when points are arranged in different vertical geometric configurations across two intervals, many observers find this task difficult. Those who can do the task tend to perceive the depth interval in one configuration as very different from depth in the other configuration. We explore two plausible explanations for this effect...
2012: Quarterly Journal of Experimental Psychology: QJEP
Itsaso Olasagasti, Christopher J Bockisch, David S Zee, Dominik Straumann
When humans are accelerated along the body vertical, the right and left eyes show oppositely directed torsional modulation (cyclovergence). The origin of this paradoxical response is unknown. We studied cyclovergence during linear sinusoidal vertical motion in healthy humans. A small head-fixed visual target minimized horizontal and vertical motion of the eyes and therefore isolated the torsional component. For stimuli between 1 and 2 Hz (near the natural range of head motion), the phase of cyclovergence with respect to inertial acceleration was 8...
July 6, 2011: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Jenny C A Read, Graeme P Phillipson, Andrew Glennerster
The literature on vertical disparity is complicated by the fact that several different definitions of the term "vertical disparity" are in common use, often without a clear statement about which is intended or a widespread appreciation of the properties of the different definitions. Here, we examine two definitions of retinal vertical disparity: elevation-latitude and elevation-longitude disparities. Near the fixation point, these definitions become equivalent, but in general, they have quite different dependences on object distance and binocular eye posture, which have not previously been spelt out...
December 9, 2009: Journal of Vision
Clifton M Schor
The near response is composed of cross-coupled interactions between convergence and other distance-related oculomotor responses including accommodation, vertical vergence, and cyclovergence. The cross-coupling interactions are analogous to the body postural reflexes that maintain balance. Near-response couplings guide involuntary motor responses during voluntary shifts of distance and direction of gaze without feedback from defocus or retinal-image disparity. They optimize the disparity stimulus for stereoscopic depth perception and can be modified by optically induced sensory demands placed on binocular vision...
July 2009: Optometry and Vision Science: Official Publication of the American Academy of Optometry
Gill Roper-Hall
The vergence system is an important element in human eye movement control. It comprises horizontal, vertical, and torsional components, the largest of which is convergence. Vergence performance is largely involuntary, although voluntary effort can influence convergence. Vergence function can be damaged by trauma or organic disease and, because convergence can be exerted voluntarily, it is susceptible to purposeful subjective disturbances. Vergence function is important in the maintenance of binocular control, being synonymous with motor fusion...
January 2009: Strabismus
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
I Olasagasti, C J Bockisch, D S Zee, D Straumann
We present results of a study of torsional eye movements evoked by earth-vertical accelerations along the subject's longitudinal axis. The earth-vertical stimulus leads to a gravito-inertial acceleration vector that changes magnitude but not direction. It can therefore be viewed as a dynamic change of the gravity level. Up-down oscillations induced relatively symmetric cyclovergence (0.6-2.2 degrees peak-to-peak). Eyes intorted/extorted for higher/lower effective gravity. The phase of this modulation was small relative to chair acceleration...
2008: Progress in Brain Research
R Becker, T Krzizok, H Wassill
PURPOSE: Positionally induced cyclotorsion could be an important factor concerning correction of astigmatism in refractive surgery. Previous studies have shown no influence of body position on cycloposition in healthy subjects with normal binocular vision. METHODS: 10 subjects (median value of age 44.2 years) without binocular vision due to an organic eye disease or to strabismus were examined using three-dimensional video-oculography (3D-VOG). This non-invasive method can record changes in the position of both eyes simultaneously in the x-, y- and z-axes...
January 2006: Klinische Monatsblätter Für Augenheilkunde
Mark M J Houben, Janine Goumans, Johannes van der Steen
PURPOSE: This study compared the performance of a video-based infrared three-dimensional eye tracker device (Chronos) with the scleral search coil method. METHODS: Three-dimensional eye movements were measured simultaneously with both systems during fixation, saccades, optokinetic stimulation, and vestibular stimulation. RESULTS: Comparison of fixation positions between -15 degrees and +15 degrees showed that horizontal and vertical eye position signals of the two systems were highly correlated (R2 = 0...
January 2006: Investigative Ophthalmology & Visual Science
Hiroyuki Ito
Our visual system matches images from both eyes to establish a single view and stereo depth even when they contain a certain amount of vertical disparity. This paper demonstrates a new stereo effect showing an aspect of vertical disparity processing. When oblique lines without disparity are overlaid with sparse random dots with vertical disparity, the lines look closer or farther in depth. The characteristics of this stereo illusion were experimentally investigated. The results showed that the sign of the perceived depth of the oblique lines depended on the combination of the line orientation and the vertical disparity sign, and that the amount of perceived depth became larger as the line orientation became more horizontal...
March 2005: Vision Research
R Becker, T H Krzizok, H Wassill
PURPOSE: Positionally induced cyclotorsion could be an important factor concerning correction of astigmatism in refractive surgery. The method of binocular three dimensional infrared video-oculography (3D-VOG) was used to determine a possible influence of body position on cyclotorsion. METHODS: 38 eyes (19 healthy subjects, median value of age 25.5) with normal binocular vision were examined using 3D-VOG. This method records ocular motions and positions of both eyes simultaneously in the x, y, and z axis...
March 2004: British Journal of Ophthalmology
M S Banks, I T Hooge, B T Backus
Rotating a surface about a horizontal axis alters the retinal horizontal-shear disparities. Opposed torsional eye movements (cyclovergence) also change horizontal shear. If there were no compensation for the horizontal disparities created by cyclovergence, slant estimates would be erroneous. We asked whether compensation for cyclovergence occurs, and, if it does, whether it occurs by use of an extraretinal cyclovergence signal, by use of vertical-shear disparities, or by use of both signals. In four experiments, we found that compensation is nearly veridical when vertical-shear disparities are available and easily measured...
2001: Journal of Vision
Raymond van Ee, Loes C J van Dam
In order to perceive depth from binocular disparities the visual system has to identify matching features of the two retinal images. Normally, the assigned disparity is unambiguously determined by monocularly visible matching constraints. The assigned disparity is ambiguous when matching is unconstrained, such as when we view an isolated long oblique disparate line. Recently we found that in order to perceive a depth probe at the same depth as the oblique line, the probe needs to have the same horizontal disparity as the line (i...
February 2003: Vision Research
Michael C Brodsky
BACKGROUND: Primitive adaptations in lateral-eyed animals have programmed the oblique muscles to counterrotate the eyes during pitch and roll. In humans, these torsional movements are rudimentary. PURPOSE: To determine whether the human oblique muscles are vestigial. METHODS: Review of primitive oblique muscle adaptations and exaptations in human binocular vision. RESULTS: Primitive adaptations in human oblique muscle function produce rudimentary torsional eye movements that can be measured as cycloversion and cyclovergence under experimental conditions...
June 2002: Archives of Ophthalmology
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
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