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Contrast is a feature of visual stimuli that characterizes the difference in brightness between dark and light regions of an image. Perception of contrast is affected by the temporal frequency and spatial frequency properties of a stimulus, and the sensitivity to contrast in sine wave stimuli is characterized by the contrast sensitivity function.
Contrast sensitivity is typically expressed as the reciprocal of the threshold contrast for detection of a given pattern (i.e., 1 ÷ contrast threshold). [15] Using the results of a contrast sensitivity exam, a contrast sensitivity curve can be plotted, with spatial frequency on the horizontal, and contrast threshold on the vertical axis.
The "LEA Numbers Test" was the second of the LEA tests that was developed and can be used to test the visual acuity of older children and even adults. This test has a layout similar to a typical Snellen chart, with lines of numbers decreasing in size towards the bottom of the page. Like the optotypes of the LEA Symbols Test, these numbers are ...
Colour sensitivity test - to assess the function of the Optic nerve; Contrast sensitivity test - to assess the function of rods photoreceptors; Visual field test - to know the extent of the individual's field that is sensitive; Near visual acuity - to assess the reading ability at near
Recordings of the primary visual cortex during contrast adaptation showed that it is the predominance of contrast sensitivity reduction that results in this adaptation. [13] Neural adaptation can affect the relative strength of the visual stimuli and can affect perceptual suppression in events such as binocular rivalry.
Another test, including Visual acuity (EVTS/OptimEyes), uses targets which change in size, contrast, and viewing time. This test was developed by Daniel M. Laby with colleagues and uses item response theory to calculate a vision performance score (core score). This specific test of visual function has been shown to correlate to professional ...
LMS (long, medium, short), is a color space which represents the response of the three types of cones of the human eye, named for their responsivity (sensitivity) peaks at long, medium, and short wavelengths. The numerical range is generally not specified, except that the lower end is generally bounded by zero.
Residual refraction cylinder (≤ 0.25 D) was 81.8% for the Contoura Vision group and 50% for the SMILE group (P < .001). Contrast sensitivity (6 cycles/degree) was 7.2 ± 1.01 in the Contoura Vision group and 6.20 ± 1.52 in the SMILE group.