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https://www.readbyqxmd.com/read/28324117/accommodation-responds-to-optical-vergence-and-not-defocus-blur-alone
#1
Antonio J Del Águila-Carrasco, Iván Marín-Franch, Paula Bernal-Molina, José J Esteve-Taboada, Philip B Kruger, Robert Montés-Micó, Norberto López-Gil
Purpose: To determine whether changes in wavefront spherical curvature (optical vergence) are a directional cue for accommodation. Methods: Nine subjects participated in this experiment. The accommodation response to a monochromatic target was measured continuously with a custom-made adaptive optics system while astigmatism and higher-order aberrations were corrected in real time. There were two experimental open-loop conditions: vergence-driven condition, where the deformable mirror provided sinusoidal changes in defocus at the retina between -1 and +1 diopters (D) at 0...
March 1, 2017: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/28241657/dynamic-visual-responses-of-accommodation-and-vergence-to-electro-holographic-images
#2
Aya Nozaki, Masaya Mitobe, Fumio Okuyama, Yuji Sakamoto
Electro-holography can display images without inducing fatigue and three-dimensional (3D) sickness, i.e., visual discomfort due to viewing a stereoscopic display. Thus, this technology is expected to be applied to 3D media. However, there are no studies that have shown the agreement between the dynamic responses of accommodation and vergence to the reconstructed images of electro-holography and those to the real targets. This paper describes the measurement results of these responses using a developed system that can simultaneously measure the dynamic responses of accommodation and vergence...
February 20, 2017: Optics Express
https://www.readbyqxmd.com/read/28222490/the-prevalence-of-convergence-insufficiency-in-iran-a-population-based-study
#3
Hassan Hashemi, Payam Nabovati, Mehdi Khabazkhoob, Hadi Ostadimoghaddam, Asgar Doostdar, Ehsan Shiralivand, Abbasali Yekta
PURPOSE: The aim was to determine the prevalence of convergence insufficiency and its relationship with age, gender and refractive error in a population-based study. METHODS: In this cross-sectional study, all residents over one year old in Mashhad city, in the north east of Iran, were sampled through random stratified cluster sampling. After selecting samples and their participation in the study, they all had eye examinations including the measurement of visual acuity, refraction, binocular vision assessment, including cover test, measurement of near point of convergence and fusional vergences and finally, slitlamp biomicroscopy...
February 21, 2017: Clinical & Experimental Optometry: Journal of the Australian Optometrical Association
https://www.readbyqxmd.com/read/28195951/assessment-of-oculomotor-function-in-patients-with-postconcussion-syndrome-a-systematic-review
#4
Foad Taghdiri, Brenda Varriano, Maria Carmela Tartaglia
BACKGROUND: Concussion and its associated sequel, postconcussion syndrome (PCS), have a debilitating impact on the lives of concussed patients. However, a diagnostic biomarker for this condition is lacking. Recently, there has been a surge of interest in using oculomotor function testing as an objective assessment of patients with PCS. OBJECTIVES: To systematically synthesize, appraise, and summarize all published empirical studies that have assessed alteration of oculomotor functions in patients with PCS...
February 10, 2017: Journal of Head Trauma Rehabilitation
https://www.readbyqxmd.com/read/28192091/the-influence-of-age-on-adaptation-of-disparity-vergence-and-phoria
#5
Tara L Alvarez, Eun H Kim, Chang Yaramothu, Bérangère Granger-Donetti
A paucity of research exists to investigate whether the normal aging process influences the ability to adapt disparity vergence and phoria. Vergence eye movements and dissociated phoria were recorded from 49 healthy subjects (ages 20-70years) using an objective eye movement tracking system. Four-degree vergence responses were modified using a double-step protocol. Dynamics of vergence were quantified via peak velocity. The phoria adaptation experiment measured the magnitude (net change in phoria level) and rate (magnitude divided by the time constant) of phoria adaption during 5min of sustained fixation on a binocular target (40cm/8...
February 16, 2017: Vision Research
https://www.readbyqxmd.com/read/28177529/a-central-mesencephalic-reticular-formation-projection-to-medial-rectus-motoneurons-supplying-singly-and-multiply-innervated-extraocular-muscle-fibers
#6
Martin O Bohlen, Susan Warren, Paul J May
We recently demonstrated a bilateral projection to the supraoculomotor area from the central mesencephalic reticular formation (cMRF), a region implicated in horizontal gaze changes. C-group motoneurons, which supply multiply innervated fibers in the medial rectus muscle, are located within the primate supraoculomotor area, but their inputs and function are poorly understood. Here we tested whether C-group motoneurons in Macaca fascicularis monkeys receive a direct cMRF input by injecting this portion of the reticular formation with anterograde tracers in combination with injection of retrograde tracer into the medial rectus muscle...
February 8, 2017: Journal of Comparative Neurology
https://www.readbyqxmd.com/read/28176802/ocular-reflex-phase-during-off-vertical-axis-rotation-in-humans-is-modified-by-head-turn-on-trunk-position
#7
Samantha B Douglas, Gilles Clément, Pierre Denise, Scott J Wood
Constant velocity Off-Vertical Axis Rotation (OVAR) imposes a continuously varying orientation of the head and body relative to gravity, which generates a modulation of horizontal (conjugate and vergence), vertical, and torsional eye movements. We introduced the head-turn-on-trunk paradigm during OVAR to examine the extent to whether the modulation of these ocular reflexes is mediated by graviceptors in the head, i.e., otoliths, versus other body graviceptors. Ten human subjects were rotated in darkness about their longitudinal axis 20° off-vertical at a constant velocity of 45 and 180°/s, corresponding to 0...
February 8, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28135308/individual-objective-and-subjective-fixation-disparity-in-near-vision
#8
Wolfgang Jaschinski
Binocular vision refers to the integration of images in the two eyes for improved visual performance and depth perception. One aspect of binocular vision is the fixation disparity, which is a suboptimal condition in individuals with respect to binocular eye movement control and subsequent neural processing. The objective fixation disparity refers to the vergence angle between the visual axes, which is measured with eye trackers. Subjective fixation disparity is tested with two monocular nonius lines which indicate the physical nonius separation required for perceived alignment...
2017: PloS One
https://www.readbyqxmd.com/read/28126262/changes-in-stimulus-and-response-ac-a-ratio-with-vision-therapy-in-convergence-insufficiency
#9
Neeraj Kumar Singh, Revathy Mani, Jameel Rizwana Hussaindeen
PURPOSE: To evaluate the changes in the stimulus and response Accommodative Convergence to Accommodation (AC/A) ratio following vision therapy (VT) in Convergence Insufficiency (CI). METHODS: Stimulus and response AC/A ratio were measured on twenty five CI participants, pre and post 10 sessions of VT. Stimulus AC/A ratio was measured using the gradient method and response AC/A ratio was calculated using modified Thorington technique with accommodative responses measured using WAM-5500 open-field autorefractor...
January 23, 2017: Journal of Optometry
https://www.readbyqxmd.com/read/28121809/eye-vergence-responses-during-a-visual-memory-task
#10
Maria Solé Puig, August Romeo, Jose Cañete Crespillo, Hans Supèr
In a previous report it was shown that covertly attending visual stimuli produce small convergence of the eyes, and that visual stimuli can give rise to different modulations of the angle of eye vergence, depending on their power to capture attention. Working memory is highly dependent on attention. Therefore, in this study we assessed vergence responses in a memory task. Participants scanned a set of 8 or 12 images for 10 s, and thereafter were presented with a series of single images. One half were repeat images - that is, they belonged to the initial set - and the other half were novel images...
February 8, 2017: Neuroreport
https://www.readbyqxmd.com/read/28114594/effects-of-pure-vergence-training-on-initiation-and-binocular-coordination-of-saccades
#11
Aurélien Morize, Dominique Brémond-Gignac, François Daniel, Zoï Kapoula
Purpose: We hypothesized that saccade eye movement properties, particularly latency and binocular coordination, depend on vergence quality. Methods: We studied 11 students clinically diagnosed for vergence disorders versus 8 healthy controls. Rehabilitation of vergence disorders was done with a novel research-based method, using vergence in midsagittal plane. Vergence and saccades were recorded in separate blocks, before and after five weekly rehabilitation sessions...
January 1, 2017: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/28095087/binocular-and-accommodative-characteristics-in-a-normal-population
#12
AbbasAli Yekta, Mehdi Khabazkhoob, Hassan Hashemi, Hadi Ostadimoghaddam, Somayeh Ghasemi-Moghaddam, Javad Heravian, Asgar Doostdar, Payam Nabovati
PURPOSE: To study binocular and accommodative characteristics and their associations with age and gender in an Iranian young adult population. METHODS: In this cross-sectional study, multistage cluster sampling was done from the students of Mashhad University of Medical Sciences. All participants had visual acuity, refraction, and cover tests followed by measurements of the near point of convergence (NPC), amplitude of accommodation (AA), monocular and binocular accommodative facility (MAF and BAF) using ±2...
March 2017: Strabismus
https://www.readbyqxmd.com/read/28088347/disparity-configuration-influences-depth-discrimination-in-na%C3%A3-ve-adults-but-not-in-children
#13
Laurie M Wilcox, Brittney Hartle, Aliya Solski, Kevin J Mackenzie, Deborah Giaschi
We report a series of experiments in which we assess depth discrimination performance in adults and children using a disparity-balanced target configuration to avoid the effects of anticipatory vergence eye movements. In our first study we found that children outperformed adults by a substantial margin, and the adults were consistently near chance. This was surprising given that we initially tested naïve adults to provide a benchmark for the children's data, and all observers met the criterion for stereoacuity...
January 25, 2017: Vision Research
https://www.readbyqxmd.com/read/28079738/vision-problems-and-reduced-reading-outcomes-in-queensland-schoolchildren
#14
Shelley Hopkins, Geoff P Sampson, Peter L Hendicott, Joanne M Wood
PURPOSE: To assess the relationship between vision and reading outcomes in Indigenous and non-Indigenous schoolchildren to determine whether vision problems are associated with lower reading outcomes in these populations. METHODS: Vision testing and reading assessments were performed on 508 Indigenous and non-Indigenous schoolchildren in Queensland, Australia divided into two age groups: Grades 1 and 2 (6-7 years of age) and Grades 6 and 7 (12-13 years of age). Vision parameters measured included cycloplegic refraction, near point of convergence, heterophoria, fusional vergence range, rapid automatized naming, and visual motor integration...
January 12, 2017: Optometry and Vision Science: Official Publication of the American Academy of Optometry
https://www.readbyqxmd.com/read/28071728/determining-the-relative-contribution-of-retinal-disparity-and-blur-cues-to-ocular-accommodation-in-down-syndrome
#15
Lesley Doyle, Kathryn J Saunders, Julie-Anne Little
Individuals with Down syndrome (DS) often exhibit hypoaccommodation alongside accurate vergence. This study investigates the sensitivity of the two systems to retinal disparity and blur cues, establishing the relationship between the two in terms of accommodative-convergence to accommodation (AC/A) and convergence-accommodation to convergence (CA/C) ratios. An objective photorefraction system measured accommodation and vergence under binocular conditions and when retinal disparity and blur cues were removed...
January 10, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28031397/electrical-stimulation-of-superior-colliculus-affects-strabismus-angle-in-monkey-models-for-strabismus
#16
Suraj Upadhyaya, Hui Meng, Vallabh E Das
Disruption of binocular vision during the critical period for development leads to eye misalignment in humans and in monkey models. We have previously suggested that disruption within a vergence circuit could be the neural basis for strabismus. Electrical stimulation in the rostral superior colliculus (rSC) leads to vergence eye movements in normal monkeys. Therefore, the purpose of this study was to investigate the effect of SC stimulation on eye misalignment in strabismic monkeys. Electrical stimulation was delivered to 51 sites in the intermediate and deep layers of the SC (400 Hz, 0...
March 1, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28002561/compensation-of-presbyopia-with-the-light-sword-lens
#17
Alejandro Mira-Agudelo, Walter Torres-Sepúlveda, John F Barrera, Rodrigo Henao, Narcyz Blocki, Krzysztof Petelczyc, Andrzej Kolodziejczyk
Purpose: We present the first physiological evaluation of the use of the light sword lens (LSL) for presbyopia compensation. The LSL is an axially asymmetric optical element designed for imaging with extended depth of focus. Methods: A monocular visual simulator setup is implemented to measure visual acuity (VA). Physiological presbyopia is "mimicked" in human subjects by paralysis of the ciliary muscle, using topical application of a muscarinic antagonist. The effect of a contact lens-configured LSL on the mimicked presbyopia visual system is evaluated by measuring VA as a function of target vergence...
December 1, 2016: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/27994843/the-role-of-vertical-disparity-in-distance-and-depth-perception-as-revealed-by-different-stereo-camera-configurations
#18
Cyril Vienne, Justin Plantier, Pascaline Neveu, Anne-Emmanuelle Priot
Vertical binocular disparity is a source of distance information allowing the portrayal of the layout and 3D metrics of the visual space. The role of vertical disparity in the perception of depth, size, curvature, or slant of surfaces was revealed in several previous studies using cue conflict paradigms. In this study, we varied the configuration of stereo-cameras to investigate how changes in the horizontal and vertical disparity fields, conflicting with the vergence cue, affect perceived distance and depth...
November 2016: I-Perception
https://www.readbyqxmd.com/read/27973591/attentional-selection-accompanied-by-eye-vergence-as-revealed-by-event-related-brain-potentials
#19
Maria Sole Puig, Josep Marco Pallarés, Laura Perez Zapata, Laura Puigcerver, Josep Cañete, Hans Supèr
Neural mechanisms of attention allow selective sensory information processing. Top-down deployment of visual-spatial attention is conveyed by cortical feedback connections from frontal regions to lower sensory areas modulating late stimulus responses. A recent study reported the occurrence of small eye vergence during orienting top-down attention. Here we assessed a possible link between vergence and attention by comparing visual event related potentials (vERPs) to a cue stimulus that induced attention to shift towards the target location to the vERPs to a no-cue stimulus that did not trigger orienting attention...
2016: PloS One
https://www.readbyqxmd.com/read/27928407/vergence-neural-pathways-a-systematic-narrative-literature-review
#20
REVIEW
Annabelle Searle, Fiona J Rowe
Research in the neural pathway for vergence is less understood in comparison to the other four visual eye movements. The aim of this study was to review the literature on vergence neural pathways and associated disorders. A review of previous published literature though to March 2016 was conducted. Intracranial pathologies that affect entire neural functioning were found to cause convergence insufficiencies. In contrast, pathologies with a more localised intracranial lesion cause more specific vergence disorders...
October 2016: Neuro-ophthalmology
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