Search results for " Binocular"
showing 10 items of 67 documents
Symptomatic accommodative and binocular dysfunctions from the use of flat-panel displays
2018
AIM: To determine the presence of symptomatic accommodative and non-strabismic binocular dysfunctions (ANSBD) in a non-presbyopic population of video display unit (VDU) users with flat-panel displays. METHODS: One hundred and one VDU users, aged between 20 to 34y, initially participated in the study. This study excluded contact-lens wearers and subjects who had undergone refractive surgery or had any systemic or ocular disease. First, subjects were asked about the type and nature of eye symptoms they experienced during VDU use. Then, a thorough eye examination excluded those subjects with a significant uncorrected refractive error or other problem, such as ocular motility disorders, vertica…
Effects of symmetry, texture, and monocular viewing on geographical slant estimation.
2018
Hills often appear to be steeper than they are. The unusual magnitude of this error has prompted extensive experimentation. The judgment mode, such as verbal vs. action-based measures, the state of the observer - whether exhausted or well rested - all can influence perceived geographical slant. We hold that slant perception is inherently shaky as soon as the slope in question is no longer palpable, that is if it is outside our personal space. To make this point, we have added symmetry, texture, and depression to the list of factors that might modulate slant perception. When the frontal slope of a hill is to be judged, it appears steeper when the side slopes are steep. We have used model hil…
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 …
Visual performance of two simultaneous vision multifocal contact lenses
2012
Purpose To evaluate and compare the visual performance of two simultaneous vision multifocal contact lenses (CLs). Methods In this cross-over study design 20 presbyopic subjects were fitted with two different simultaneous vision multifocal CLs (the PureVision Multifocal Low Add and Acuvue Oasys for Presbyopia) in random order. After 1 month, binocular distance visual acuity (BDVA) under photopic (85 cd/m2) and mesopic (3 cd/m2) conditions, binocular near visual acuity (BNVA), binocular distance contrast sensitivity function (CSF) under photopic and mesopic conditions, binocular near CSF and defocus curve were measured. Subjects were then refitted with the alternative correction and the proc…
Quality of vision with the Acri. Twin asymmetric diffractive bifocal intraocular lens system.
2007
To assess the quality of vision in patients who had implantation of asymmetric Acri. Twin bifocal diffractive intraocular lenses (IOLs) by evaluating distance and near visual acuities and photopic and mesopic contrast sensitivity under monocular and binocular conditions.Fernández-Vega Ophthalmological Institute, Oviedo, Spain.The study comprised 343 consecutive patients who had bilateral implantation of the Acri. Twin system: a distance-weighted 737D IOL and a near-weighted 733D IOL. Monocular and binocular best corrected distance visual acuities, best distance corrected near visual acuity, and distance contrast sensitivity under photopic (85 cd/m(2)) and mesopic (5 cd/m(2)) conditions were…
Visual function after implantation of a diffractive aspheric trifocal intraocular lens
2016
Purpose To evaluate distance, intermediate, and near vision after bilateral implantation of a diffractive aspheric trifocal intraocular lens (IOL). Methods This study enrolled 204 eyes of 102 patients who had bilateral implantation of the AT LISA tri 839MP IOL. Monocular and binocular uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA) (4 meters), monocular and binocular uncorrected near visual acuity (UNVA) and distance-corrected near visual acuity (DCNVA) (30, 40 centimeters), binocular uncorrected intermediate visual acuity (UIVA) and distance-corrected intermediate visual acuity (DCIVA) (50, 60, 70 centimeters), the defocus curve, and binocular photopic…
Fixation pattern analysis with microperimetry in nystagmus patients
2015
Objective: To assess the usefulness of microperimetry (MP) as an additional objective method for characterizing the fixation pattern in nystagmus. Design: Prospective study. Participants: Fifteen eyes of 8 subjects (age, 12–80 years) with nystagmus from the Lluís Alcanyís Foundation (University of Valencia, Spain) were included. Methods: All patients had a comprehensive ophthalmologic examination including a microperimetric examination (MAIA, CenterVue, Padova, Italy). The following microperimetric parameters were evaluated: average threshold (AT), macular integrity index (MI), fixating points within a circle of 1° (P1) and 2° of radius (P2), bivariate contour ellipse area (BCEA) considerin…
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…
Vision evaluation in people with Down's syndrome.
1994
We tested the colour vision of 72 people with Down's syndrome using the Ishihara test and an anomaloscope. We found that 13 of the subjects, 6 males and 7 females, had defective colour vision according to Pickford's classification. In monocular vision 10 eyes were protan (five simple, three extreme and two deviant), one eye was simple deuteranomalous and the remaining eyes were normal: in binocular vision four of the subjects were protan (two simple and two deviant), two subjects were deutan (one simple and one deviant) and the rest were normal. Many of our subjects had lens opacities, strabismus, nystagmus, hypermetropia, high myopia and astigmatism, confirming literature reports. The cont…
Symmetric bilateral implantation of a distance-dominant diffractive bifocal intraocular lens
2007
To assess visual results after symmetrical bilateral implantation of a distance-dominant bifocal diffractive intraocular lens (IOL).Fernández-Vega Ophthalmological Institute, Oviedo, Spain.Fifty patients had bilateral implantation of a distance-dominant diffractive bifocal 447D IOL (Acri.Tec GmbH) in a prospective study. Monocular and binocular best corrected distance visual acuities and best distance-corrected near visual acuity, binocular best distance-corrected intermediate visual acuity, and distance contrast sensitivity under photopic (85 cd/m(2)) and mesopic (5 cd/m(2)) conditions were determined.At the 6-month postoperative visit, the mean binocular best corrected distance acuity and…