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The results of the systemic treatment of binocular vision and of amblyopia in children with eccentric fixation
Published in Jan-Tjeerd de Faber, 28th European Strabismological Association Meeting, 2020
Teresa Baranowska-George, Lidia Puchalska-Niedbal
We present the behaviour of visual acuity in a squinting eye with initial excentric fixation by mean of long-term systematic treatment with the localization method. The material for studies included 20 children with initial poor visual acuity of the squinting eye (0.02 Snellen test).The subjects were systematic treatment with an eye patch and localization method during 6 years period received.They also had tests of binocular function carried out and a test of their capacity to perceive binocular rivalry using slides in a Synoptophore. We pay attention to the improvement of visual acuity depends on the consolidation of the normal binocular vision.
Visual systems
Published in Nicholas Green, Steven Gaydos, Hutchison Ewan, Edward Nicol, Handbook of Aviation and Space Medicine, 2019
Nicholas Green, Steven Gaydos, Hutchison Ewan, Edward Nicol
Binocular rivalry: results from presentation of dissimilar images to each eye (dichoptic viewing). Can be induced by differences in image colour, resolution, field of view, motion, luminance or displacement.Brain resolves this problem by suppressing one of the images, most commonly from non-dominant eye.May be difficult to make necessary attention switch to attend to appropriate visual input.Can lead to significant fatigue, especially during a long sortie or in situations where there is obvious system flicker or poor image quality: Bright green phosphor in right eye, leading to difficulty in attending to a darker visual scene via left eye (e.g. cockpit).Bright city lights causing difficulty in shifting view to HMD.
Neural adaptation to blur
Published in Pablo Artal, Handbook of Visual Optics, 2017
Michael A. Webster, Susana Marcos
Surprisingly, however, the adaptation of perceived blur is instead strongly binocular. Mon-Williams et al. (1998) showed that adapting to defocus in one eye affected visual acuity through the other, though the effect was smaller in the nonadapted eye. Kompaniez et al. (2013) instead examined the effects on subjective focus when the adapt and test images were shown to the same or different eyes. In this case, the aftereffects showed almost complete transfer between the eyes. Moreover, when observers were adapted to different blur levels in the two eyes, the aftereffects of perceived focus were similar through either eye and dominated by the sharper of the two images. This dominance is consistent with how we subjectively experience differences in blur between the two eyes or when focused and blurred images are superimposed. The sharper image determines the perceived focus and strongly suppresses the blur in the second image (Georgeson et al. 2007). This suppression is also found in binocular rivalry—where different images that cannot be fused are shown to each eye. The sharper image again strongly dominates (Fahle 1982; Arnold et al. 2007). Adaptation to these interocular differences may aid the utility of monovision corrections for presbyopia, where one eye is focused for far and the other for near (Radhakrishnan et al. 2014).
Late Surgical Correction of Longstanding Constant Strabismus in Adults: Is Fusion Possible in All Successfully Aligned Patients?
Published in Journal of Binocular Vision and Ocular Motility, 2020
Sühan Tomaç, Enes Uyar, Tuğrul Akın, Fatih Mehmet Mutlu, Halil İbrahim Altınsoy
Kushner and Morton2 and Murray et al.5 found a binocular response in adult patients after surgical alignment when tested with the BSG test (86% and 88%, respectively); however, they did not explain whether the responses were at near or distance. With the BSG test, all of our patients and all the patients of Dickmann et al.6 showed a fusion response at near, whereas 29 (87%) of our patients, and 9 (69%) of their patients showed fusion at distance. Although they described their results as an anomalous binocular cooperation, findings of our study together with their study suggested the different results between near and distance may be due to the increase of binocular rivalry at distance. On the other hand, Morris et al.3 and Scott et al.4 reported the results of W4D test at near as peripheral fusion, but did not report the results of the W4D test at distance in their patients after surgical alignment. On the W4D test, 25 (75%) of our patients and 6 (46%) of the patients of Dickmann et al.6 showed anomalous fusion at near, whereas 7 (21%) of our patients and 5 (38%) of their patients showed anomalous fusion at distance.
The Role of Binocularity in Anisometropic Amblyopia
Published in Journal of Binocular Vision and Ocular Motility, 2019
Sarah J. Murray, Charlotte J. Codina
The level of binocular rivalry and suppression can be altered in normal observers and to varying degrees by the manipulation of a uniocular image. There were four propositions about binocular rivalry made by Willem Levelt in 1965 that were ‘updated’ by JW Brascamp and colleagues.36 They are as follows: A stronger stimulus signal will increase the predominance of that eye’s perception.Increasing the interocular difference between the stimuli will lengthen the average time of perceptual dominance of the stronger stimulus.Increasing the interocular difference between the stimuli will lead to a reduced perceptual alteration rate.Equally increasing stimulus strength to both eyes increases the perceptual alteration rate.
Vision in children with autism spectrum disorder: a critical review
Published in Clinical and Experimental Optometry, 2018
In a recent study, Karaminis et al.2017 investigated binocular rivalry in ASD. Binocular rivalry occurs when the two eyes are presented with images that are not compatible, and to avoid confusion of this percept, visual perception oscillates between the two images from each eye, and may amalgamate for brief periods of time. Inhibition of visual information is required for binocular rivalry to occur, and some studies have reported that cortical inhibition is atypical in ASD, due to altered release and signalling of excitatory and inhibitory neurotransmitters.2003 Therefore Karaminis et al.2017 hypothesised that if there were an imbalance in the excitation/inhibition neural mechanisms in ASD, then binocular rivalry would be altered. They investigated this in 16 children with ASD aged 7–14-years and typically developing age‐ and IQ‐matched controls and reported that while there was no difference in the number of transitions of fixation between the ASD and control participants, children with ASD showed shorter durations of mixed percepts. They concluded that the dynamics of binocular rivalry are altered in ASD.