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https://www.readbyqxmd.com/read/28439978/simulation-of-commercial-vs-theoretically-optimised-contact-lenses-for-presbyopia
#1
Richard Legras, David Rio
PURPOSE: To compare theoretically optimised bifocal contact lens optical designs to commercially available optical designs for presbyopia. METHODS: Retinal images were simulated, using a numerical eye model, from -6 (i.e., near vision) to +2 D for each 0.25 D. Ten optical profiles were simulated. Four of them corresponded to commercial contact lenses (i.e., Acuvue Oasys for Presbyopia®, Air Optix Aqua Multifocal®, Purevision Multifocal® and Distance Biofinity Multifocal®)...
May 2017: Ophthalmic & Physiological Optics: the Journal of the British College of Ophthalmic Opticians (Optometrists)
https://www.readbyqxmd.com/read/28424868/non-invasive-measurements-of-the-dynamic-changes-in-the-ciliary-muscle-crystalline-lens-morphology-and-anterior-chamber-during-accommodation-with-a-high-resolution-oct
#2
José J Esteve-Taboada, Alberto Domínguez-Vicent, Daniel Monsálvez-Romín, Antonio J Del Águila-Carrasco, Robert Montés-Micó
PURPOSE: The purpose of the study was to assess non-invasively the changes in the anterior chamber eye, crystalline lens morphology, and ciliary muscle during accommodation by means of an anterior chamber optical coherence tomographer (OCT), and correlate them with vergence. METHODS: Twenty-five eyes of twenty-five healthy subjects, whose mean age was 29.9±7.1 years, were included and measured with an anterior chamber OCT. The central corneal thickness (CCT), anterior chamber depth (ACD), anterior crystalline lens radius of curvature (ALRC), crystalline lens thickness (CLT), and ciliary muscle area (CMA) were measured for each participant at 0, -1, -2, and -3 D of target vergence...
April 20, 2017: Graefe's Archive for Clinical and Experimental Ophthalmology
https://www.readbyqxmd.com/read/28380953/compact-see-through-3d-head-mounted-display-based-on-wavefront-modulation-with-holographic-grating-filter
#3
Qiankun Gao, Juan Liu, Xinhui Duan, Tao Zhao, Xin Li, Peilin Liu
A compact see-through three-dimensional head-mounted display (3D-HMD) is proposed and investigated in this paper. Two phase holograms are analytically extracted from the object wavefront and uploaded on different zones of the spatial light modulator (SLM). A holographic grating is further used as the frequency filter to couple the separated holograms together for wavefront modulation. The developed preliminary prototype has a simple optical facility and a compact structure (133.8mm × 40.4mm × 35.4mm with a 47...
April 3, 2017: Optics Express
https://www.readbyqxmd.com/read/28380093/assessing-the-accommodation-response-after-near-visual-tasks-using-different-handheld-electronic-devices
#4
Aikaterini I Moulakaki, Alberto Recchioni, Antonio J Del Águila-Carrasco, José J Esteve-Taboada, Robert Montés-Micó
Purpose: To assess the accommodation response after short reading periods using a tablet and a smartphone as well as determine potential differences in the accommodation response at various stimulus vergences using a Hartmann- Shack aberrometer. Methods: Eighteen healthy subjects with astigmatism of less than 1 D, corrected visual acuity of 20/20 or better, and normal findings in an ophthalmic examination were enrolled. Accommodation responses were obtained under three different conditions: accommodation system of the eye relaxed and visually stressed with a tablet and an smartphone for 10 min, at a distance of 0...
January 2017: Arquivos Brasileiros de Oftalmologia
https://www.readbyqxmd.com/read/28355633/combining-1-d-components-to-extract-pattern-information-it-is-about-more-than-component-similarity
#5
Christian Quaia, Lance M Optican, Bruce G Cumming
At least under some conditions, plaid stimuli are processed by combining information first extracted in orientation and scale-selective channels. The rules that govern this combination across channels are only partially understood. Although the available data suggests that only components having similar spatial frequency and contrast are combined, the extent to which this holds has not been firmly established. To address this question, we measured, in human subjects, the short-latency reflexive vergence eye movements induced by stereo plaids in which spatial frequency and contrast of the components are independently varied...
March 1, 2017: Journal of Vision
https://www.readbyqxmd.com/read/28348893/effect-of-illumination-on-ocular-status-modifications-induced-by-short-term-3d-tv-viewing
#6
Yuanyuan Chen, Yuwen Wang, Xinping Yu, Aiqin Xu, Jian Jiang, Hao Chen
Objectives. This study aimed to compare changes in ocular status after 3D TV viewing under three modes of illumination and thereby identify optimal illumination for 3D TV viewing. Methods. The following measures of ocular status were assessed: the accommodative response, accommodative microfluctuation, accommodative facility, relative accommodation, gradient accommodative convergence/accommodation (AC/A) ratio, phoria, and fusional vergence. The observers watched 3D television for 90 minutes through 3D shutter glasses under three illumination modes: A, complete darkness; B, back illumination (50 lx); and C, front illumination (130 lx)...
2017: Neural Plasticity
https://www.readbyqxmd.com/read/28324117/accommodation-responds-to-optical-vergence-and-not-defocus-blur-alone
#7
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
#8
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
#9
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
#10
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
#11
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
#12
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...
June 1, 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
#13
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
#14
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
#15
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
#16
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
#17
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
#18
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
#19
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
#20
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
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