Disparity Vergence Dynamics and Fixation Disparity

Schor, Clifton; Robertson, Kenneth M.; Wesson, Michael D.

doi:10.1097/00006324-198608000-00003

Cited by 17 publications

(13 citation statements)

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“…This shift could be due to several factors. For one, with dichoptic viewing and despite a binocularly fused fixation point, fixation disparities could result from normal vergence dynamics Patel et al, 2001;Schor et al, 1986!. Consequently, the disktarget presented to one eye and the ring-mask presented to the other may not be concentric~i.e., may be shifted!…”

Section: Resultsmentioning

confidence: 99%

Central factors contributing to para-contrast modulation of contour and brightness perception

2007

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Following up on a prior study of contour and brightness processing in visual masking (Breitmeyer et al., 2006), we investigated the effects of a binocular and dichoptic para-contrast masking on the visibility of the contour and brightness of a target presented to the other eye. Combined, the results support the contributions of several cortical processes to para-contrast: (1) two central sources of inhibition, one long-latency and prolonged and the other short-latency and brief; (2) binocular rivalry suppression; and (3) a facilitatory effect peaking at different SOAs for the contour and the brightness tasks, reflecting; (4) known properties of two separate cortical systems, one a fast contour-processing pathway and the other a slower brightness-processing pathway.

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Section: Resultsmentioning

confidence: 99%

Central factors contributing to para-contrast modulation of contour and brightness perception

2007

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“…14,15 Size, spatial-frequency content, and clarity of the target can affect the precision of oculomotor control, and the sustained vergence system is reportedly more sensitive to high-spatial-frequency detail than low-spatial-frequency detail. 16 In studies of the precision of visually stabilized gaze, the precision of the fixation target is of obvious importance, and degradation of acuity should be prevented.…”

mentioning

confidence: 99%

Effects of Scleral Search Coil Wear on Visual Function

Irving

Zacher

Allison

et al. 2003

Invest. Ophthalmol. Vis. Sci.

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“…A recent investigation using functional MRI suggested that the neural correlates for vergence adaptation may involve the oculomotor vermis in the cerebellum, the cuneus, and the primary visual cortex, 46 although another recent study using continuous theta-burst repetitive transcranial magnetic stimulation failed to show a relationship between posterior cerebellar disruption and vergence adaptation. 47 Schor et al 48 have modeled factors that determine the slope of the fixation disparity curve. If vergence adaptation is not generated during fixation disparity testing, either because an individual's vergence adaptation system is inefficient or because there is insufficient time to allow for vergence adaptation, then the slope of the fixation disparity is determined by two variables.…”

Section: Relationship Between Fixation Disparity and Disparity Vergencementioning

confidence: 99%

“…56 These investigators asserted that fixation disparity is a necessary or "purposeful" vergence error that is required to maintain a particular vergence posture. 48,56 Fixation disparity in this conception is considered normal, although the amplitude of fixation disparity may vary according to the efficiency of disparity vergence. In Schor's 56 model, if the fast disparity vergence gain is high, or the fast disparity vergence rate of decay is low, or vergence adaptation is high, or more than one of these things are true, then fixation disparity could be near zero.…”

Section: The Origin Of Fixation Disparitymentioning

confidence: 99%

Topical Review: Methodological Variables in Clinical and Laboratory Measurements of Fixation Disparity

Fogt

2023

Optom Vis Sci

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Significance Fixation disparity is a small vergence error that does not disrupt fusion. Fixation disparity measures correlate with binocular symptoms. This paper covers methodological differences between clinical fixation disparity measurement devices, findings when objective and subjective fixation disparities are compared, and the potential impact of binocular capture on fixation disparity measurements. Fixation disparity is a small vergence error that occurs in non-strabismic individuals and does not disrupt fusion. This paper reviews clinical fixation disparity variables and their clinical diagnostic value. Clinical devices that are used to measure these variables are described as are studies in which the output from these devices have been compared. Methodological differences between the devices such as the location of the fusional stimulus, the rate at which judgments of dichoptic alignment are made, and the strength of the accommodative stimulus are all considered. In addition, the paper covers theories of the neural origins of fixation disparity and control systems models incorporating fixation disparity. Studies in which objective fixation disparities (oculomotor portion of fixation disparity assessed with an eye tracker) and subjective fixation disparities (sensory portion of fixation disparity assessed psychophysically with dichoptic Nonius lines) have been compared are also examined, and consideration is given to why some investigators find differences in these measures while other investigators do not. The conclusion thus far is that there are likely complex interactions between vergence adaptation, accommodation, and the location of the fusional stimulus that lead to differences in objective and subjective fixation disparity measures. Finally, capture of the visual direction of monocular stimuli by adjacent fusional stimuli and the implications for fixation disparity measures are considered.

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Disparity Vergence Dynamics and Fixation Disparity

Cited by 17 publications

References 0 publications

Central factors contributing to para-contrast modulation of contour and brightness perception

Central factors contributing to para-contrast modulation of contour and brightness perception

Effects of Scleral Search Coil Wear on Visual Function

Topical Review: Methodological Variables in Clinical and Laboratory Measurements of Fixation Disparity

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