SEARCH · PubMed Health
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
An improved chromatic rotatable refraction test for simultaneous spheric and astigmatic refraction is described. Its new features are interposition of a bright yellow stripe between the conventional red and green fields and a pair of parallel test lines, which traverse vertically all colored fields. Thereby astigmatic errors become easily visible.
Explore the source record for details and available documents.
The diagnostic value of Lüscher's colour test for the estimation of emotional state of children and juveniles (teenagers) with central nervous system's organic alteration and borderline psychopathological disturbances was analysed. Moreover a number of other additional tests were used namely the colour estimation of current and optimal state, the measurement of personal emotional anxiety according to Scott scale as well as the comparison of colour selection results and colour perception in dream. It was demonstrated that color selection results depended upon both neuroticism level and presence or type of psychopathological disturbances. They had their own specificity if organic CNS alteration took place and were determined by pathological focus localization. The psychological characteristics that were symbolized in colours according to Lüscher corresponded mainly to personal peculiarities in both neurosis-like and certain types of psychopathological alteration in which the definite colours were preferable.
Explore the source record for details and available documents.
A microcomputer program for the Apple II family of computers on a monochrome and a color screen is described. The program draws most of the tests used by ophthalmologists, and is offered as an alternative to a projector system. One advantage of the electronic generation of drawings is that true random orientation of Pflueger's E is possible. Tests are included for visual acuity (Pflueger's E, Landolt rings, numbers and children's drawings). Colored tests include a duochrome test, simple color vision tests, a fixation help with a musical background, a cobalt blue test and a Worth figure. In the astigmatic dial a mobile pointer helps to determine the axis. New tests can be programmed by the user and exchanged on disks among collageues.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Fifteen normal and 18 red-green-deficient subjects were tested with the Farnsworth Dichotomous Test of color vision (Panel D-15) and with an alternative version of the dichotomous test consisting of selected color chips from the Farnsworth-Munsell 100-Hue Test. Results indicate that the 100-Hue version of the dichotomous test is equivalent to the standard Panel D-15 with respect to detecting and differentiating among the more severe red-green deficiencies. These results confirm A. Pinckers' previous suggestion that the 100-Hue Test contains the components necessary for a Farnsworth Panel D-15.
The early diagnostic of glaucoma (before the appearance of visual field defects) can be made in some cases with the help of certain objective tests and, to a lesser degree, with subjective or psychophysical tests. Retinal nerve fiber layer photography is certainly the most rewarding objective test, providing the technique has been mastered and there is a clear fundus view without chorio-retinal atrophy. The identification of nerve fiber defects is an almost sure sign of glaucomatous damage in the absence of other pathology. An abnormally small neuroretinal rim area can also be an indicator of glaucoma. However, no conclusion can be drawn if the value is within the wide range of normal limits. Electrophysiological tests in glaucoma patients at the present time give results that show too much variability and overlap with those of normals to be of practical value. The same can be said for subjective tests such as spatial and temporal contrast sensitivity (the flicker test, for example). The specificity and sensitivity of the tests are too weak to be useful for the diagnosis of glaucoma in 1992.
Observation suggests that the chromatic changes which elicit an impression of transparency include translations and convergences in color space. Neither rotations nor shears in color space lead to perceived transparency. Results of matching experiments show that equiluminous translations, which cannot be generated by episcotister or filter models, give rise to the perception of transparency. This implies that systematic luminance change is not needed for transparency to be perceived. These results were used for the development of a method for detecting a transparent overlay within a color image and for separating the overlay from the underlying surfaces. The method tests for the coherence of chromatic change along contours through X-junctions to help detect the contour of a transparent region. The algorithm tests locally for translation and convergence to detect a transparent region. It estimates globally the chromatic parameters of the transparent overlay in order to separate the overlay from the underlying surfaces.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Patients with a history of retinal detachment were examined by the following tests: (1) setting of an isoluminant match between yellow and green constituent squares of a checkerboard and (2) measurement of the flicker fusion frequency for a contrast-reversal of this yellow-green pattern. The results suggest that the test may provide useful data for assessing the severity of any damage to a given part of the retina. The fusion frequencies range from over 10 Hz (normal) to about 2 Hz for a severely impaired retina. The data for the relative amounts of red and green light needed to achieve a match rarely show any abnormality; thus, a standard anomaloscope test or pseudoisochromatic plates would not detect these deficiencies.
A new test of peripheral color contrast is described. A high-definition color monitor driven by a personal computer with a graphics interface card displays an annulus subtending 25 degrees at the eye. The color contrast between the annulus and the background can be varied. Forty-five degrees of the annulus is randomly removed in one of four quadrants. Patients are asked to identify the position of the gap while fixating a central spot. The minimum color contrast between annulus and background at which the identification is possible is between 13-16% for the protan, deuteran, and tritan axis in normal subjects. This threshold value changes little with age, refractive error, or pupillary aperture, and test-retest variability is low. Testing one eye takes only 1-2 min. The test was applied to ocular-hypertensive and glaucomatous patients. All patients with glaucoma had thresholds greater than two standard deviations (SD) above the normal mean. In addition, 97% of glaucoma patients had thresholds greater than four SDs, and 95% had thresholds more than five SDs above the normal mean. Most patients with ocular hypertension and clinical signs indicating a low or medium risk of conversion to glaucoma had thresholds under the upper limit of normal. High-risk patients with ocular hypertension fell into two groups. One approximated to normal; the other had elevated thresholds, which in many cases were more than four SDs above the normal mean. The epidemiologic consequences of this test are discussed.
Simple color-difference formulae and pictorial images have traditionally been used to estimate the visual impact of color errors introduced by image-reproduction processes. But the limited gamut of RGB cameras constrains such analyses, particularly of natural scenes. The purpose of this work was to estimate visual sensitivity to color errors introduced deliberately into pictures synthesized from hyperspectral images of natural scenes without gamut constraints and to compare discrimination thresholds expressed in CIELAB and S-CIELAB color spaces. From each original image, a set of approximate images with variable color errors were generated and displayed on a calibrated RGB color monitor. The threshold for perceptibility of the errors was determined in a paired-comparison experiment. In agreement with previous studies, it was found that discrimination between original and approximate images needed on average a CIELAB color difference DeltaEab* of about 2.2. Although a large variation of performance across the nine images tested was found when errors were expressed in CIELAB units, little variation was obtained when they were expressed in S-CIELAB units.