Ocular torsion: sensorimotor principles.

D L Guyton

doi:10.1007/bf02181189

Home/Archive/PubMed

PubMed · 3402747

Ocular torsion: sensorimotor principles.

D L Guyton

View original source ↗Export metadata ↓

Abstract

Eye movements are basically limited to two degrees of freedom, as described by Donders' and Listing's laws. Complex patterns of innervation maintain the geometric constancy of the retinal meridians, presumably via visual feedback acting through orientation-specific neurons in the cortex. Interactions between torsional and vertical movements of the eyes can be demonstrated by stimulating ocular torsion and detecting secondary vertical deviations. Geometric considerations show that significant peripheral disparities occur with convergence and eye movements, dictating large Panum's fusional areas in the periphery. Good visual acuity in man must thus be limited to the fovea, but the large peripheral Panum's fusional areas allow sensory cyclofusion of up to 8 degrees. In addition, motor cyclofusion occurs in the presence of large-field stimuli, further helping to minimize problems from torsional diplopia both in normal individuals and in patients with ocular motor pareses.

Explore related subjects

Convergence, Ocular Eye Movements Feedback Humans Models, Biological Oculomotor Muscles Vision, Ocular Visual Acuity Visual Fields Journal Article

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

D L Guyton. 1988. Ocular torsion: sensorimotor principles.. https://doi.org/10.1007/bf02181189

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2006

Depth scaling in phantom and monocular gap stereograms using absolute distance information.

The present study aimed to investigate whether the visual system scales apparent depth from binocularly unmatched features by using absolute distance information. In Experiment 1 we examined the effect of convergence on perceived depth in phantom stereograms [Gillam, B., & Nakayama, K. (1999). Quantitative depth for a phantom surface can be based on cyclopean occlusion cues alone. Vision Research, 39, 109-112.], monocular gap stereograms [Pianta, M. J., & Gillam, B. J. (2003a). Monocular gap stereopsis: manipulation of the outer edge disparity and the shape of the gap. Vision Research, 43, 1937-1950.] and random dot stereograms. In Experiments 2 and 3 we examined the effective range of viewing distances for scaling the apparent depths in these stereograms. The results showed that: (a) the magnitudes of perceived depths increased in all stereograms as the estimate of the viewing distance increased while keeping proximal and/or distal sizes of the stimuli constant, and (b) the effective range of viewing distances was significantly shorter in monocular gap stereograms. The first result indicates that the visual system scales apparent depth from unmatched features as well as that from horizontal disparity, while the second suggests that, at far distances, the strength of the depth signal from an unmatched feature in monocular gap stereograms is relatively weaker than that from horizontal disparity.

Convergence, Ocular↗

PubMed2006

Capture of visual direction in dynamic vergence is reduced with flashed monocular lines.

The visual direction of a continuously presented monocular object is captured by the visual direction of a closely adjacent binocular object, which questions the reliability of nonius lines for measuring vergence. This was shown by Erkelens, C. J., and van Ee, R. (1997a,b) [Capture of the visual direction: An unexpected phenomenon in binocular vision. Vision Research, 37, 1193-1196; Capture of the visual direction of monocular objects by adjacent binocular objects. Vision Research, 37, 1735-1745] stimulating dynamic vergence by a counter phase oscillation of two square random-dot patterns (one to each eye) that contained a smaller central dot-free gap (of variable width) with a vertical monocular line oscillating in phase with the random-dot pattern of the respective eye; subjects adjusted the motion-amplitude of the line until it was perceived as (nearly) stationary. With a continuously presented monocular line, we replicated capture of visual direction provided the dot-free gap was narrow: the adjusted motion-amplitude of the line was similar as the motion-amplitude of the random-dot pattern, although large vergence errors occurred. However, when we flashed the line for 67 ms at the moments of maximal and minimal disparity of the vergence stimulus, we found that the adjusted motion-amplitude of the line was smaller; thus, the capture effect appeared to be reduced with flashed nonius lines. Accordingly, we found that the objectively measured vergence gain was significantly correlated (r=0.8) with the motion-amplitude of the flashed monocular line when the separation between the line and the fusion contour was at least 32 min arc. In conclusion, if one wishes to estimate the dynamic vergence response with psychophysical methods, effects of capture of visual direction can be reduced by using flashed nonius lines.

Convergence, Ocular↗

PubMed2006

The extended horopter: quantifying retinal correspondence across changes of 3D eye position.

The theoretical horopter is an interesting qualitative tool for conceptualizing binocular correspondence, but its quantitative applications have been limited because they have ignored ocular kinematics and vertical binocular sensory fusion. Here we extend the mathematical definition of the horopter to a full surface over visual space, and we use this extended horopter to quantify binocular alignment and visualize its dependence on eye position. We reproduce the deformation of the theoretical horopter into a spiral shape in tertiary gaze as first described by Helmholtz (1867). We also describe a new effect of ocular torsion, where the Vieth-Müller circle rotates out of the visual plane for symmetric vergence conditions in elevated or depressed gaze. We demonstrate how these deformations are reduced or abolished when the eyes follow the modification of Listing's law during convergence called L2, which enlarges the extended horopter and keeps its location and shape constant across gaze directions.

Convergence, Ocular↗