Development of a Spatio-temporal Contrast Sensitivity Test for Clinical Use (original) (raw)
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Spatio-temporal Contrast Sensitivity in the Cardinal Directions of the Colour Space. A Review
Journal of Optometry, 2010
We review the psychophysics of the spatio-temporal contrast sensitivity in the cardinal directions of the colour space and their correlation with those neural characteristics of the visual system that limit the ability to perform contrast detection or pattern-resolution tasks. We focus our attention particularly on the influence of luminance level, spatial extent and spatial location of the stimuli-factors that determine the characteristics of the physiological mechanisms underlying detection. Optical factors do obviously play a role, but we will refer to them only briefly. Contrast sensitivity measurements are often used in clinical practice as a method to detect, at their early stages, a variety of pathologies affecting the visual system, but their usefulness is very limited due to several reasons. We suggest some considerations about stimuli characteristics that should be taken into account in order to improve the performance of this kind of measurement.
Factors Affecting Contrast Sensitivity in Healthy Individuals: A Pilot Study
Turkish journal of ophthalmology, 2017
To determine the demographic and ocular features affecting contrast sensitivity levels in healthy individuals. Seventy-four eyes of 37 subjects (7-65 years old) with refractive errors less than 1.0 diopter, no history of ocular surgery, and 20/20 visual acuity were included in the study. The participants were divided by age into three groups: group 1, 7-19 years, n=11; group 2, 20-49 years, n=15; and group 3, 50-65 years, n=11. All subjects underwent anterior and posterior segment evaluation, intraocular pressure measurements, refraction measurements, and clinical evaluation for strabismus. Contrast static test was performed using Metrovision MonPack 3 vision monitor system after measuring pupil diameter. Photopic and mesopic measurements were taken sequentially from right eyes, left eyes, and both eyes together. Contrast sensitivity at intermediate and high spatial frequencies was lower with increasing age. Binocular measurements were better than monocular, and mesopic measurements...
Contrast sensitivity to patch stimuli: Effects of spatial bandwidth and temporal presentation
Spatial Vision, 1993
Allstrad-Modeis ofthe spatial response ofhuman vision are important for applied work, but the available contrast sensitivity function (CSF) data vary widely due to the diverse spatiotemporal stimuli used over the years. To assist selection, this paper: (I) reports measurements of the effects on the CSF of varying the spatial and temporal windows of grating patches; (2) demonstrates that the widely discrepant CSFs from previous studies can be accounted for by using these results; and (3) discusses simple criteria for choosing CSFs for practical applications. CSFs were measured for several combinations of spatial and temporal waveforms, using the same subjects under otherwise identical conditions. The CSF was measured over the range of 0.5-10c/deg using Gabor-type patches of 1.0-, 0.5-, 0.25-, and 0.125-octave spatial bandwidths using both abrupt and gradual temporal presentations. The results were compared with the CSF obtained with a fixed aperture (4 deg x 4 deg) grating pattern. Increasing the number ofcycles resulted in increased sensitivity at intermediate frequencies, changing the CSF to a narrower bandpass shape. For each patch bandwidth. the gradual presentation CSF had a narrower spatial pass band than with the abrupt presen tation. The relevance ofthe large differences in the CSFs obtained with different stimuli to our understand ing of visual performance is discussed.
Contrast Sensitivity Studies and Test- Review
Biomedical Journal of Scientific & Technical Research, 2020
Contrast sensitivity (CS) expresses the quality of human vision. This article presents the main points for the interpretation of CS and what structures of the eye and brain contribute to achieving it. There is still information on the ways and types of CS clinical examination, factors and conditions affecting it, and the latest technological developments in its measurement.
Contrast Sensitivity Studies and Test- A Review
International Journal of Ophthalmology and Clinical Research, 2020
Contrast sensitivity (CS) expresses the quality of human vision. This article presents the main points for the interpretation of CS and what structures of the eye and brain contribute to achieving it. There is still information on the ways and types of CS clinical examination, factors and conditions affecting it, and the latest technological developments in its measurement.
Objective measurement of contrast sensitivity function using contrast sweep visual evoked responses
British Journal of Ophthalmology, 1998
Aim/background-The contrast sensitivity function (CSF) measurement provides information that is not accessible by standard visual acuity determinations. The contrast sweep pattern reversal visual evoked responses (CSVER) technique was used to objectively measure the CSF in clinical practice. Methods-The contrast thresholds were measured at five spatial frequencies in 10 normal subjects. The CSVER were recorded with sinusoidally modulated vertical gratings at 10 contrast levels (96, 64, 48, 32, 16, 8, 4, 2, 1, and 0.5%) presented in five spatial frequencies (0.5, 1.0, 2.0, 4.0, and 8.0 cycles per degree). Each of 10 contrast levels was displayed for 2 seconds at the desired spatial frequency. The CSVER amplitudes at the second harmonic were calculated by discrete Fourier transform. The results were compared with those obtained using a psychophysical method. Results-An inverted U-shaped CSF which peaked at 2.0 cycles per degree with a contrast sensitivity of 34.5 (contrast, 2.9%) was observed. The CSF assessed electrophysiologically was 0.62 to 0.79 log units lower than the sensitivity measured using the psychophysical method. However, the overall shapes were highly correlated. Conclusion-One can objectively measure CSF with CSVER and this may be useful in patients in whom the psychophysical method is limited. (Br J Ophthalmol 1998;82:168-173)
Psychophysical scaling of contrast sensitivity in three different spatial frequencies
F1000Research, 2014
Introduction •Contrast Sensitivity (CS) is the fundamental measurement regarding the basis of the spatial vision. •A typical CS function shows a band-pass shape with higher sensitivity between 2 to 6 cpd. • Regarding the extensive studies of contrast sensitivities very few are focused in the suprathreshold perception. • According to Steven’s Law the sensation magnitude (ψ) grows as a power function of the stimulus magnitude (φ):
Precision and Normative Values of a New Computerized Chart for Contrast Sensitivity Testing
Scientific Reports, 2019
The purpose was to define a normative database for a grating test for contrast sensitivity, based on a chart monitor with high-definition liquid crystal display, and validate its measurements by assessing their repeatability and determining responsiveness to cataract surgery. Three samples were analyzed: (1) healthy volunteers to assess the repeatability of measurements, (2) healthy subjects to develop the normative database, (3) patients undergoing cataract surgery. All subjects were tested with the grating contrast sensitivity test (Vision Chart, CSO) at 1.5, 3, 6, 12 and 18 cycles per degree. The instrument software progressively reduces the contrast of the gratings according to the Quick Estimate by Sequential Testing (QUEST) procedure. In the subjects of the first sample, three consecutive measurements were taken and repeatability was assessed on the basis of the intra-session test-retest variability and the coefficient of variation. The test offered high repeatability, with te...
Neuroscience & Medicine, 2011
We developed a psychophysical paradigm for the clinical assessment of the contrast sensitivity (CS) mediated by the ON-and OFF-systems of the Magnocellular and Parvocellular pathways. We designed a stimulus considering two dimensions: two spatial frequencies (0.5 and 4.5 cpd) and two temporal rates of flicker (33 ms and 1500 ms). To evidence the ON-and OFF responses, the CS was measured for two polarities of light with luminance changes of 0.6 dB steps above and below the medium luminance grey background. We tested 38 healthy volunteers. The results shows that Magnocellular contrast sensitivity was higher than Parvocellular for the 33 ms flickering stimulus and the Parvocellular contrast sensitivity was higher than Magnocellular for 1500 ms stimuli. The reliability of the test was checked and confirmed. We concluded that the test performs a rapid measurement of the CS mediated by the ON and OFF systems of Magnocellular and Parvocellular pathways. It is useful in clinical protocols due to its high sensitivity and good reliability.