Search results for "fixation disparity"
showing 4 items of 4 documents
Subjective fixation disparity affected by dynamic asymmetry, resting vergence, and nonius bias.
2011
PURPOSE This study was undertaken to investigate how subjectively measured fixation disparity can be explained by (1) the convergent-divergent asymmetry of vergence dynamics (called dynamic asymmetry) for a disparity vergence step stimulus of 1° (60 arc min), (2) the dark vergence, and (3) the nonius bias. METHODS Fixation disparity, dark vergence, and nonius bias were measured subjectively using nonius lines. Dynamic vergence step responses (both convergent and divergent) were measured objectively. RESULTS In 20 subjects (mean age, 24.5 ± 4.3 years, visual acuity, ≥1.0; all emmetropic except for one with myopia, wearing contact lenses), multiple regression analyses showed that 39% of the v…
Monocular Versus Binocular Calibrations in Evaluating Fixation Disparity With a Video-Based Eye-Tracker
2015
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. This study includes a test of the precision of both monocular and …
Relation between fixation disparity and the asymmetry between convergent and divergent disparity step responses
2007
Abstract The neural network model of Patel et al. [Patel, S. S., Jiang, B. C., & Ogmen, H. (2001). Vergence dynamics predict fixation disparity. Neural Computation, 13 (7), 1495–1525] predicts that fixation disparity, the vergence error for a stationary fusion stimulus, is the result of asymmetrical dynamic properties of disparity vergence mechanisms: faster (slower) convergent than divergent responses give rise to an eso (exo) fixation disparity, i.e., over-convergence (under-convergence) in stationary fixation. This hypothesis was tested in the present study with an inter-individual approach: in 16 subjects we estimated the vergence step response to a 1 deg disparity stimulus with a subje…
Fiksācijas disparitāte un konverģences nepietiekamība.
2020
Maģistra darbs ir uzrakstīts angļu valodā uz 47 lapām, tas satur 19 attēlus, 14 tabulas un 51 atsauci uz literatūras avotiem. Mērķis bija novērtēt fiksācijas disparitātes saistību ar konverģences nepietiekamību. Pētījumam bija divas daļas: 1. grupā bija 5 dalībnieki ar konverģences nepietiekamību, kas veica 12 nedēļu ilgu redzes terapiju, lai izvērtētu tās ietekmi uz binokulārajām funkcijām, lasīšanas ātrumu, CISS vērtējumu un fiksācijas disparitāti; 2. grupā bija 51 dalībnieks, kuri aizpildīja CISS aptauju un veica fiksācijas disparitātes mērījumus, lai izvērtētu šo divu parametru saistību. Redzes treniņi būtiski uzlaboju konverģence tuvuma punktu un pozitīvās fūzijas rezerves, kā arī sama…