Search results for " Monocular"
showing 8 items of 8 documents
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…
Accommodative stimulus-response curves to low-pass filtered natural images
2018
To assess how the monocular steady-state accommodative stimulus-response curve is modified when viewing low-pass filtered natural images. Eighteen adult subjects participated in the study. The accommodative stimulus-response curve was objectively assessed by means of a Hartmann-Shack wavefront sensor. Measurements were taken at different accommodative demands. Target images were low-pass filtered versions of a natural image that were obtained applying different digital spatial filters that limited the spatial frequency content of the natural image. Cutoff spatial frequencies were set at 30, 21, and 15 cycles per degree (cy/deg). Mean data obtained for each target were fitted to linear model…
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 …
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…
Monocular versus binocular pupillometry.
2004
Purpose To quantify differences between monocular and binocular pupil size measurement under scotopic and mesopic conditions. Setting Department of Ophthalmology, Johannes Gutenberg-University, and Department of Medical Biometry, Epidemiology and Informatics, University of Mainz, Mainz, Germany. Methods Computerized dynamic pupillometry (P2000 SA, Procyon Instruments Ltd.) was used at 3 illumination levels: scotopic at 0.03 lux, mesopic low at 0.82 lux, and mesopic high at 6.4 lux. One hundred forty eyes of 70 healthy volunteers without ocular pathology were examined. The subjects were divided into 2 groups. In the first group, the pupil diameter was measured binocularly first. In the secon…
Contrast sensitivity after refractive lens exchange with a multifocal diffractive aspheric intraocular lens
2013
Purpose: To evaluate distance and near contrast sensitivity (CS) under photopic and mesopic conditions before and after refractive lens exchange (RLE) and implantation of the aspheric AcrySof ReSTOR (SN6AD3 model) intraocular lens (IOL) Methods: Sixty eyes of 30 consecutive patients after RLE underwent bilateral implantation with the aspheric AcrySof ReSTOR IOL. The patients sample was divided into myopic [n=15, mean spherical equivalent (SE) -6.87± 2.03 diopters (D)] and hyperopic (n=15, mean SE +4.52±1.14 D) groups. Monocular uncorrected visual acuity at distance and near (UCVA and UCNVA, respectively) and monocular best corrected visual acuity at distance and near (BCVA and BCNVA, respec…
Visual Acuity and Contrast Sensitivity in Eyes Implanted with Aspheric and Spherical Intraocular Lenses
2009
Purpose To compare visual acuity and contrast sensitivity (CS) in eyes implanted with aspheric and spherical intraocular lenses (IOLs) after cataract surgery. Design Randomized, prospective study. Participants Five hundred twenty-four eyes from 262 cataract surgery patients implanted with 2 IOL models: the AcrySof IQ (262 eyes) and AcrySof SN60AT (262 eyes; Alcon Laboratories, Fort Worth, TX). Methods High-contrast photopic best-corrected distance visual acuity (BCVA) and CS under photopic (85 cd/m 2 ) and mesopic (6 cd/m 2 ) conditions were measured. Pupil diameter was analyzed for distance vision under both lighting conditions. Follow-up was carried out for 6 months in all patients. Main …
Visual Comparison of an Artificial Pupil Contact Lens to Monovision
2012
PURPOSE To assess and compare the effects of contact-lens based artificial pupil design and monovision correction on visual performance. METHODS In a cross-over study design, 22 presbyopic patients (age range 50 to 64 years) were evaluated using artificial pupil contact lens on the non-dominant eye and monovision. After 1 month, binocular distance visual acuity (BDVA), binocular near visual acuity (BNVA), defocus curve, binocular distance contrast sensitivity, binocular near contrast sensitivity, and stereoacuity were measured, under photopic conditions (85 cd/m2), in each patient after contact lens fitting. Moreover, BDVA and binocular distance contrast sensitivity were examined under meso…