Rapid monocular adaptation of saccade amplitude in constant strabismus
Jan-Tjeerd de Faber in 28th European Strabismological Association Meeting, 2020
This present study found anomalous disconjugacy in two subjects with small angled strabismus. Bucci et al. (1997) found anomalous disconjugacy only in subjects with large angle strabismus and no fusion. They proposed that this might be driven by monocular visual inputs occurring to improve fixation of each eye and not to reduce binocular disparity. They suggest that the movements of the two eyes are controlled independently, so-called utrocular vision (or vision with each eye separately), as described by Schor (1991). This is a primitive form of binocular vision found in vertebrates with complete decussation of the visual pathways. Bucci et al. (1997) suggested that this form of independent eye control could allow avoidance of diplopia, but not establishment of a true binocular linkage.
Normal and Abnormal Development of the Neuronal Response Properties in Primate Visual Cortex
Jon H. Kaas, Christine E. Collins in The Primate Visual System, 2003
FIGURE 4.2 Normal development of binocular disparity sensitivity in simple (open circles and left vertical axis) and complex cells (filled circles) of monkey V1.31 The development of stereopsis in monkeys (open squares and right vertical axis) is also plotted based on the data published by O'Dell and Boothe.58 Vertical stippled area indicates the ages during which stereopsis emerges in normal monkeys.
A longitudinal study of local stereoacuity and associated factors in schoolchildren: The Shahroud Schoolchildren Eye Cohort Study
Published in Clinical and Experimental Optometry, 2023
Hassan Hashemi, Mehdi Khabazkhoob, Payam Nabovati, Mohammad Hassan Emamian, Akbar Fotouhi
Stereoacuity is the lowest degree of horizontal binocular disparity that can lead to depth perception and is known as the threshold of stereopsis.1,2 Stereopsis significantly affects the performance of fine visuomotor actions and spatial representation in children.3,4 Impaired stereoacuity is associated with poor performance in tasks requiring precise eye-hand coordination and visuomotor skills.4,5 Fine stereoacuity has also been linked to better reading ability and academic performance in children.6,7 Failure to timely diagnose stereoacuity disorder and manage its underlying causes in the critical period may lead to a permanent loss of stereopsis.8 Therefore, it is important to recognise the risk factors associated with poor stereoacuity.8
Phoria Adaptation: The Ghost in the Machine
Published in Journal of Binocular Vision and Ocular Motility, 2020
Michael C. Brodsky
Binocular disparity does not generate phoria adaptation. There is always binocular disparity in a complex world (in different planes even when the eyes are aligned), and this binocular disparity is a necessary stimulus for stereopsis. While binocular retinal image disparity provides the stimulus for the fast fusional vergence system, it is the motor signal from the fast fusional vergence system that serves as the error signal for phoria adaptation.5 The input to the slow neural integrator for phoria adaptation is generated by the output or effort of fast fusional vergence. Because there has to be an effort to fuse for phoria adaptation to be recruited, fixation disparity induced by a conflict in vergence and accommodation may provide a driving stimulus for prism-induced phoria adaptation9 (Figure 1). The fast vergence system has a neural integrator with a short half-life of 10–15 s.7,14 By contrast, phoria adaptation consists of a more stable neural integrator that leaks with a much longer time constant (varying from minutes to several days).5,9 The output of the slow neural integrator allows for a reciprocal reduction of the output of fast fusional vergence by means of the negative feedback loop in which the system is trying to adapt until the phoria is controlling the entire response.9 As the slow fusional vergence system charges up, the fast fusional vergence system decays to maintain a constant total output.6,7 This feedback loop presumably reduces the fatigue and eyestrain that would result from the prolonged use of the fast vergence system.7–9
Stereopsis: are we assessing it in enough depth?
Published in Clinical and Experimental Optometry, 2018
Anna R O'connor, Laurence P Tidbury
Stereoacuity is traditionally considered as the threshold measure of how well an individual can interpret binocular disparity as perceived depth, by determining the spatial correlation of points projected onto the retina. As a physical object moves toward or away from an individual, a number of factors change, including monocular cues, and the two binocular cues to depth. Any point forward of where the eyes are fixated provides crossed disparity, that is, these points are projected on the temporal retina of both eyes. This is binocular disparity, as the corresponding point to the temporal retina of one eye, is the nasal point of the other eye.
Related Knowledge Centers
- Eye
- Stereopsis
- Visual Cortex
- Parallax
- Pupillary Distance
- Visual Angle
- Cardinal Point
- Neuron
- Receptive Field
- Stimulus