visual acuity

physiology

Learn about this topic in these articles:

major reference

  • cross section of the human eye
    In human eye: Visual acuity

    As has been stated, the ability to perceive detail is restricted in the dark-adapted retina when the illumination is such as to excite only the scotopic type of vision; this is in spite of the high sensitivity of the retina to light under…

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  • cross section of the human eye
    In human eye: Visual acuity

    Although the resolving power of the retina depends, in the last analysis, on the size and density of packing of the photoreceptors in the retina, it is the neural organization of the photoreceptors that determines whether the brain will be able to make…

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practice in perceptual learning

  • ambiguous picture
    In perception: Effects of practice

    …example, effects of practice on visual acuity were studied by requiring observers to detect simple orientation (left or right) in a row of leaning letters; e.g., . Practice tended to lower acuity thresholds, defined as the lowest intensity of illumination at which each observer could detect the orientation. Or, observers…

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test for eye function

  • LASIK
    In eye disease: Ophthalmological examination

    …important subjective test is for visual acuity. This is usually performed by having the patient read, from a set distance, an eye chart with a series of letters of graded sizes, which become increasingly smaller as the chart is read from top to bottom. The person is asked to read…

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