Search results for " Vision"
showing 10 items of 2709 documents
Effects of high doses of toluene on color vision.
1999
High exposure to toluene may cause optic neuropathy and retinopathy, both associated with dyschromatopsia. Another solvent, ethanol, is known to induce acute blue-yellow dyschromatopsia. This study investigated the acute effects of high doses of toluene on color vision. Eight male printshop workers were examined before and after cleaning printing containers with pure toluene. After cleaning, concentrations of toluene in blood were between 3.61 and 7.37 mg/l. Color vision was tested with the Farnsworth panel D-15 test, the Lanthony desaturated panel D-15 test, and the Standard Pseudoisochromatic Plates part 2. For control of possible acute effects, eight workers of a metal-working factory wi…
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…
Synergy of spatial frequency and orientation bandwidth in texture segregation
2021
Defining target textures by increased bandwidths in spatial frequency and orientation, we observed strong cue combination effects in a combined texture figure detection and discrimination task. Performance for double-cue targets was better than predicted by independent processing of either cue and even better than predicted from linear cue integration. Application of a texture-processing model revealed that the oversummative cue combination effect is captured by calculating a low-level summary statistic (\(\Delta CE_m\)), which describes the differential contrast energy to target and reference textures, from multiple scales and orientations, and integrating this statistic across channels wi…
On orienting the hand to reach and grasp an object.
1996
Subjects were required to reach and grasp a parallelepiped, the position, orientation and size of which were varied. The kinematics of reaching and grasping movements was studied in full vision and in no vision conditions. Both direction and movement amplitude of reaching were affected by object orientation. Conversely, both the time course of finger axis orientation and the angular displacement of the hand at wrist were influenced by object position. These results were not modified by the absence of visual control. Finger aperture during grasping was affected by both object size and orientation. This latter result was not due to a distorted size perception, as shown by a control matching e…
Recognition of Root Canal Orifices in Video Sequences as a Future Support System During Endodontic Treatment
2009
Abstract Introduction The objective of this study was to show the practical application of computer-aided techniques for detecting root canal orifices through the access cavity using a video camera mounted on a microscope. Methods A minimum distance classification image recognition algorithm was tested in an in vitro study to assess the possibilities of computer-aided recognition of root canal orifices. A Motic DM143 digital stereo microscope (Motic Germany GmbH, Wetzlar, Germany) was used because it includes a video camera that can be connected via USB1.1 to any computer. Results The newly developed software is capable of communicating with a video camera and can automatically detect the r…
The effect of spherical aberration on visual performance and refractive state for stimuli and tasks typical of night viewing
2018
Purpose: The aim of this work was to examine the impact of Seidel spherical aberration (SA) on optimum refractive state for detecting and discriminating small bright lights on a dark background. Methods: An adaptive-optics system was used to correct ocular aberrations of cyclopleged eyes and then systematically introduce five levels of Seidel SA for a 7-mm diameter pupil: 0, ± 0.18, and ± 0.36 diopters (D) mm−2. For each level of SA, subjects were required to detect one or resolve two points of light (0.54 arc min diameter) on a dark background. Refractive error was measured by adjusting stimulus vergence to minimize detection and resolution thresholds. Two other novel focusing tasks for si…
Electrophysiological findings of neuronal ceroid lipofuscinosis in heterozygotes.
1988
Nineteen obligate heterozygotes, 8 individuals at risk of being heterozygote, and 10 patients afflicted with four different forms of neuronal ceroid lipofuscinosis were examined electrophysiologically. The group of obligate heterozygotes was compared to age-matched control groups. Statistically significant differences were found between scotopic b-wave amplitudes, P-ERG amplitudes, and EOG light peaks of the obligate carriers of the juvenile type and the control subjects. The photopic L-ERGs and the latencies of the VEPs were mostly within the normal range. The findings represent the first evidence of functional ophthalmological changes in obligate carriers of neuronal ceroid lipofuscinosis…
Influence of optic quality on contrast sensitivity and visual acuity in eyes with a rigid or flexible phakic intraocular lens
2009
Purpose To determine whether the difference in optic quality between 2 types of phakic intraocular lenses (pIOLs) affects visual quality. Setting Fundacion Oftalmologica del Mediterraneo, Valencia, Spain. Methods Before implantation of a pIOL for myopia, all eyes had an examination including corrected (CDVA) and uncorrected (UDVA) distance visual acuity testing, corneal endothelial cell count (ECC), and intraocular pressure (IOP) measurement. The postoperative outcomes, determined at least 1 year after surgery, were CDVA; UDVA; contrast sensitivity function under photopic, mesopic, and mesopic with glare conditions; ECC; IOP; keratometry (Scheimpflug photography); and total ocular aberratio…
Effect of Color on Contrast Sensitivity with Two Different Accommodative Stimuli
1993
We studied the influence of color and accommodation on the contrast sensitivity function (CSF). At the same time, we measured the effect of axial chromatic aberration (ACA) on the CSF. The CSF's of two observers were determined using red, green, blue, and white light, at 5- and 0.5-m viewing distances. At 5 m the CSF's were measured with natural vision and also with lenses which compensated the ACA. Results show that the effect of ACA on the CSF is to reduce the sensitivity to blue with respect to the red. The difference in sensitivity between these two colors is between 50 and 150% and varies with the frequency and the subject. When the ACA is compensated the influence of the color on the …
Visual Acuity in Simple Myopic Astigmatism: Influence of Cylinder Axis
2006
Purpose. The relationship between astigmatic refractive errors and their associated visual acuity has been studied in recent years in the context of refractive power space. The influence of the axis of astigmatism remains a matter of controversy. Our goal in this study is to provide additional experimental evidence to clarify this subject. The influence of the simulated axis orientation was compared with other factors that affect visual acuity such as the particular design of the test and the differences between eyes. Methods. Simple myopic astigmatism from 0 to 3.00 D, in steps of 0.25 D, and with five different axes between 0° and 90°, were simulated on four healthy eyes of young observer…