Read by QxMD icon Read

'Fixation disparity'

Anna Przekoracka-Krawczyk, Alicja Brenk-Krakowska, Pawel Nawrot, Patrycja Rusiak, Ryszard Naskrecki
Purpose: Individuals with developmental dyslexia suffer not only from reading problems as more general motor deficits can also be observed in this patient group. Both psychometric clinical tests and objective eyetracking methods suggest that unstable binocular fixation may contribute to reading problems. Because binocular instability may cause poor eye-hand coordination and impair motor control, the primary aim of this study was to explore in dyslexic subjects the influence of unstable binocular fixation on reaction times (RTs) and implicit motor learning (IML), which is one of the fundamental cerebellar functions...
December 1, 2017: Investigative Ophthalmology & Visual Science
L de Meij, M A J Telleman, M R C Luijten, J R Polling, M Gutter
PURPOSE: Fixation disparity (FD) is a small misalignment of the eyes within the normal alignment when viewing under binocular condition. Ogle's apparatus measures FD. Standards of procedures vary, which may lead to different outcomes. METHODS: Students with normal ocular alignment, stereopsis ≤60 seconds of arc and visual acuity <0.1 logMAR, were included in this prospective comparative study. Four procedures (P1-P4) of measuring FD with Ogle's apparatus were performed with divergent placement of the line (P1 and P3), or the line moving from subjective zero (P1 and P2: prisms of ascending strength; P3 and P4: prisms alternating base in base out; combined and P4)...
September 2017: Strabismus
Yi-Ting Hsiao, Richard Shillcock, Mateo Obregón, Hamutal Kreiner, Matthew A J Roberts, Scott McDonald
We explore two aspects of exovergence: we test whether smaller binocular fixation disparities accompany the shorter saccades and longer fixations observed in reading Chinese; we test whether potentially advantageous psychophysical effects of exovergence (cf. Arnold & Schindel, 2010; Kersten & Murray, 2010) transfer to text reading. We report differential exovergence in reading Chinese and English: Chinese readers begin fixations with more binocular disparity, but end fixations with a disparity closely similar to that of the English readers...
July 11, 2017: Quarterly Journal of Experimental Psychology: QJEP
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
C Bourdy, Y James
We propose the presentation on a stereoscopic screen of the electronic eikonometer tests intended for analysis and measurement of perceptual effects of binocular disparity. These tests, so-called "built-in magnification tests" are constructed according to the same principle as those of preceding eikonometers (disparity variation parameters being included in each test presentation, which allows, for test observation and measurements during the examination, the removing of any intermediate optical system). The images of these tests are presented separately to each eye, according to active or passive stereoscopic screen technology: (1) Ogle Spatial Test to measure aniseikonia; (2) Fixation Disparity test: binocular nonius; (3) retinal correspondence test evaluated by nonius horopter; (4) stereoscopic test using Julesz' random-dot stereograms (RDS)...
May 2016: Journal Français D'ophtalmologie
Thomas A Aller, Maria Liu, Christine F Wildsoet
PURPOSE: Most studies have reported only minimal reductions in myopia progression with bifocal or progressive multifocal spectacles, although somewhat larger, although mostly still clinically insignificant, effects have been reported in children with nearpoint esophoria and/or accommodative dysfunctions. The CONTROL study was a 1-year, prospective, randomized, clinical trial of bifocal contact lenses for control of myopia in children with eso fixation disparities at near. METHODS: Eighty-six myopic subjects, aged 8 to 18 years, were enrolled in the study after passing the screening examination...
April 2016: Optometry and Vision Science: Official Publication of the American Academy of Optometry
Aiga Švede, Elīna Treija, Wolfgang Jaschinski, Gunta Krūmiņa
When measuring fixation disparity (an oculomotor vergence error), the question arises as to whether a monocular or binocular calibration is more precise and physiologically more appropriate. In monocular calibrations, a single eye fixates on a calibration target that is taken as having been projected onto the center of the fovea; the corresponding vergence state represents the heterophoria (the resting vergence position), which has no effect on the calibration procedure. In binocular calibrations, a vergence error may be present and may affect the subsequent measurement of the fixation disparity during binocular recordings...
2015: Perception
Mark Nawrot, Brian Connelly, Keith Stroyan
For fixed binocular disparity (BD), the relationship between viewing distance and relative depth is well known, the distance-square law. Similarly, perceived depth from motion parallax (MP) varies with viewing distance. Here, depth of a non-fixated object (d) varies with distance to the point of fixation (f), the retinal image velocity of the object (dθ), and velocity of the pursuit eye movement required to maintain fixation (dα). The relationship, termed the motion/pursuit ratio, is: d = dθ/dα * f . Here we investigated how the cues of vergence and accommodation contribute to apparent viewing distance in MP by assessing perceived depth magnitude...
2015: Journal of Vision
Stéphane Clery, Bruce Cumming, Hendrikje Nienborg
The stereoscopic depth of a target can be evaluated relative to the fixation plane (absolute disparity) or relative to a background (relative disparity). Fine disparity discrimination is thought to rely on relative disparity judgments (Prince et al., 2000). V2 neurons are the first in the visual processing hierarchy to show selectivity for relative disparity (Thomas et al., 2002), and have previously been found to have decision-related activity for coarse disparity discrimination tasks (Nienborg and Cumming, 2006, 2009)...
2015: Journal of Vision
T Rowan Candy, Erin Babinsky, Tawna Roberts, Vivian Manh, Eric Seemiller, Yifei Wu, Don Lyon
PURPOSE: Focused binocular fixation on a target relies on a combination of accommodation and vergence oculomotor responses. These require recalibration during early development, as a result of changes in refractive error and increases in inter-pupillary distance (IPD). This study tracked the roles of blur and disparity cues in these motor responses during this period. METHODS: 103 infants were followed from 3 months until 3 years of age. Their accommodation and vergence responses to a movie with naturalistic spatial amplitude spectra were recorded simultaneously using eccentric photorefraction and Purkinje image tracking (PowerRefractor, MCS)...
2015: Journal of Vision
Charles Leek, Stephen Johnston, Filipe Cristino
The recognition of 3D object shape is a fundamental issue in vision science. Although our knowledge has advanced considerably, most prior studies have been restricted to 2D stimulus presentation that ignores stereo disparity. In previous work we have shown how analyses of eye movement patterns can be used to elucidate the kinds of shape information that support the recognition of multi-part 3D objects (e.g., Davitt et al. , JEP: HPP, 2014, 40, 451-456). Here we extend that work using a novel technique for the 3D mapping, and analyses, of eye movement patterns under conditions of stereo viewing...
2015: Journal of Vision
Shingo Tanaka, Ichiro Fujita
UNLABELLED: Even when we view an object from different distances, so that the size of its projection onto the retina varies, we perceive its size to be relatively unchanged. In this perceptual phenomenon known as size constancy, the brain uses both distance and retinal image size to estimate the size of an object. Given that binocular disparity, the small positional difference between the retinal images in the two eyes, is a powerful visual cue for distance, we examined how it affects neuronal tuning to retinal image size in visual cortical area V4 of macaque monkeys...
August 26, 2015: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Jung-Hee Lee, Ki-Ho Na, Jin-Hyok Kim, Ho-Yeon Jeong, Dong-Gune Chang
PURPOSE: Previous investigations have recognized the critical role of pelvic parameters in the setting of a fixed sagittal deformity. Pelvic incidence (PI) is a constant, as everyone knows. However, PI might change reciprocally because of increased shear force on the sacroiliac joint, following surgical correction of fixed lumbar lordosis (LL). The disparity in PI after surgery according to the surgical method, and its impact on final follow-up, has not been reported. This study was undertaken to analyze the disparity of PI before and after surgery, and to evaluate its impact on final sagittal alignment in surgically corrected lordosis when there is immediate postoperative normal alignment following correction of adult sagittal deformity...
November 2016: European Spine Journal
Avery H Weiss, John P Kelly, Richard A Hopper, James O Phillips
PURPOSE: To characterize conjugate eye movements in Crouzon syndrome (CS) patients with and without strabismus. METHODS: Smooth pursuit, saccades, horizontal optokinetic nystagmus (OKN), and horizontal vestibulo-ocular reflex (VOR) were recorded using binocular video-oculography (VOG) in 10 children with CS (5 orthotropic, 5 strabismic) and 12 age-matched controls. Hess-Lancaster plots were generated from Orbit 1.8 using rectus muscle pulley locations from computed tomography imaging...
July 2015: Investigative Ophthalmology & Visual Science
Yuanwu Cao, Zixian Chen, Chun Jiang, Shengcheng Wan, Xiaoxing Jiang, Zhenzhou Feng
PURPOSE: This paper is to evaluate the efficacy and safety of transforaminal lumbar interbody fusion (TLIF) using unilateral pedicle screws along with contralateral translaminar facet joint screw (UPS+TFS) fixation in comparison with the method using bilateral pedicle screws fixation (BPS) in degenerative lumbar diseases. METHODS: Forty patients with single-level lumbar diseases were divided into two groups randomly. One group was treated by TLIF with BPS fixation while the other group was treated by the new technique with UPS+TFS fixation...
November 2015: European Spine Journal
Ensen Ma, Tianbin Song, Hui Zhang, Jie Lu, Liwen Wang, Qichao Zhao, Runcai Guo, Miao Li, Guolin Ma, Guangming Lu, Kefeng Li
BACKGROUND AND OBJECTIVE: There is a growing consensus that schizophrenia is ultimately caused by abnormal communication between spatially disparate brain structures. White matter fasciculi represent the primary infrastructure for long distance communication in the brain. In this study, we aimed to investigate the white matter connection in schizophrenia susceptible brain regions of early growth response factor 3 (EGR3) expressing rats. METHODS: A rat model of schizophrenia was created by the transfection of the EGR3 gene into rat hippocampus...
2015: Neuropsychiatric Disease and Treatment
Paul E Matuszewski, Tae Won Kim, Andre N Gay, Samir Mehta
Advances in surgical techniques have increased the role of early surgical intervention for isolated diaphyseal humerus fractures. The goal of this study was to investigate the following: (1) the current trend of operative treatment; (2) factors that affect surgical treatment; and (3) the effect of surgical fixation on length of stay, complication rates, and hospital disposition. The National Trauma Data Bank from 2004 to 2006 was analyzed. All patients with multiple injuries that included closed humeral shaft fractures and all patients with isolated humeral shaft fractures were included...
June 2015: Orthopedics
Emily Dodwell, James Wright, Roger Widmann, Flo Edobor-Osula, Ting-Jung Pan, Stephen Lyman
BACKGROUND: Disparities exist in access to outpatient pediatric orthopaedic care. The purpose of this study was to assess whether disparities also exist in elective pediatric orthopaedic surgical procedures such as implant removal, and to determine which demographic and socioeconomic factors may be associated with differences in treatment. METHODS: Children aged 7 to 18 inclusive who sustained femoral shaft fractures between the years 1997 and 2010 were identified in the New York State SPARCS database...
July 2016: Journal of Pediatric Orthopedics
Bram-Ernst Verhoef, Kaitlin S Bohon, Bevil R Conway
Binocular disparity is a powerful depth cue for object perception. The computations for object vision culminate in inferior temporal cortex (IT), but the functional organization for disparity in IT is unknown. Here we addressed this question by measuring fMRI responses in alert monkeys to stimuli that appeared in front of (near), behind (far), or at the fixation plane. We discovered three regions that showed preferential responses for near and far stimuli, relative to zero-disparity stimuli at the fixation plane...
April 29, 2015: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
C Speeg-Schatz, S Gottenkiene, J S Raul, A Sauer
Whiplash is a lay term combining all the complications of a cervical sprain or distortion associated with an extension. It may lead to cervical or back pain, but patients may also complain about functional visual impairment. These visual complaints: fixation disparity, heterophoria or convergence insufficiency, are frequently neglected and difficult to quantitate and treat. Establishing the relationship between the indirect cervical trauma and the visual signs may be challenging for the medical-legal expert and must include consideration of the previous oculomotor status of the patient...
May 2015: Journal Français D'ophtalmologie
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"