Method and apparatus for determining visual latency
First Claim
1. A method of testing vision, including the steps ofproducing randomly time-separated groups of visual stimuli each group consisting of a predetermined number of successive stimuli, each stimulus in a said group being separated from the next stimulus in that group by a controllable-length time interval,varying the length of each said controllable-length time interval, andassessing the minimum said controllable-length time interval for which the subject under test can discern the separate stimuli.
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Abstract
Apparatus and methods for testing temporal resolution of vision in a human subject are disclosed in which a light source is repetitively energized to produce pairs of visual stimuli, and the time interval between two stimuli in each pair is varied so as to enable the assessment of the minimum interval for which the subject under test can discern the separate stimuli in the pair. Means are provided for fixating the center of the subject'"'"'s visual field, and the position of the visual stimuli within the visual field is varied so as to enable a map to be drawn showing the variation of the subject'"'"'s temporal resolution over his visual field. Temporal resolution measured in this way enables certain diseases to be diagnosed and distinguished.
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Citations
32 Claims
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1. A method of testing vision, including the steps of
producing randomly time-separated groups of visual stimuli each group consisting of a predetermined number of successive stimuli, each stimulus in a said group being separated from the next stimulus in that group by a controllable-length time interval, varying the length of each said controllable-length time interval, and assessing the minimum said controllable-length time interval for which the subject under test can discern the separate stimuli.
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13. A method of testing vision, comprising the steps of
producing a visual stimulus of periodically varying intensity for a small discrete portion of a subject'"'"'s visual field, changing the amplitude of the intensity variations, and assessing the minimum amplitude value for which the subject can discern the variations.
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19. Apparatus for testing vision, including
visual stimulus means, activating means connected to the visual stimulus means and operative to produce therefrom randomly time-separated groups of visual stimuli, each group consisting of a predetermined number of successive stimuli with each stimulus in a said group being separated from the next stimulus therein by a controllable-length time interval, and control means connected to the activating means to vary the said controllable-length time intervals so as to enable the minimum said interval discernible by a subject under test to be assessed.
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27. Apparatus for testing vision including:
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visual stimulus means, activating means connected to the visual stimulus means and repetitively operative to produce therefrom a group of visual stimuli containing a predetermined number of successive stimuli, and control means connected to the activating means to vary the time intervals between the stimuli in each group so as to enable the minimum interval discernible by a subject under test to be assessed; the visual stimulus means comprising first and second light sources each for producing light of a first predetermined color, third and fourth light sources each for producing light of a second predetermined color, a patterned partial-mirror carrying a pattern of light reflecting strips and being light-transmitting between the strips, means mounting the first and third light sources to direct light towards one surface of the mirror whence it is reflected by the said strips in a predetermined direction, means mounting the second and fourth light sources to direct light towards the opposite surface of the said mirror whence it passes through the mirror between the said strips and in the said predetermined direction, the first and second predetermined colors beings selected whereby when all four light sources are producing light of substantially equal luminance, the composite beam of differently colored light proceeding in the said predetermined direction produces a third predetermined color but when the luminance of the light from the first and third light sources is given a step change in a predetermined direction and, simultaneously, the luminance of the light from the second and fourth light sources is given an equal step change in the opposite direction, the said composite beam produces a pattern of the first and second colors, the luminances of the light sources being connected to be controlled by the said control means whereby the said visual stimuli are produced by changes in the form of the said composite beam.
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28. Apparatus for testing vision, comprising
fixation means for fixating the subject'"'"'s visual field, light source means for producing a small discrete visual stimulus in a portion of the visual field, means for altering the physical relationship between the fixation means and the light source means whereby to shift the small discrete visual stimulus to a different portion of the visual field, first control means for giving the visual stimulus a periodically varying intensity, and second control means for changing the amplitude of the intensity variations to assess the minimum amplitude value for which the subject can discern the variations.
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30. A method of testing a human subject'"'"'s vision, including the steps of
providing a fixation mark for fixating the subject'"'"'s visual field, providing a predetermined level of background illumination over the subject'"'"'s visual field, presenting, at a first position relative to the fixation mark, randomly time-separated groups of visual stimuli each group consisting of two stimuli separated by a controllable-length time interval, carrying out a series of tests during which the lengths of the controllable-length time intervals are varied and the minimum controllable-length time interval for which the subject under test can discern the separate stimuli in each group is assessed, and
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31. presenting further said groups of visual stimuli at another position relative to the fixation mark, and carrying out another said series of tests thereat.
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32. Apparatus for testing a human subject'"'"'s vision, comprising
fixation means for presenting a fixation mark to the subject for fixating the subject'"'"'s visual field, means positioned relative to the fixation means for providing a predetermined level of background illumination for the subject'"'"'s visual field, visual stimulus means arranged to produce visual stimuli which each occupy a small, discrete, portion of the visual field, means for supporting the fixation means and the visual stimulus means for relative movement whereby to move the visual stimulus means within the subject'"'"'s visual field, activating means connected to the visual stimulus means and operative to produce therefrom randomly time-separated groups of visual stimuli each group consisting of a pair of stimuli separated by a controllable-length time interval, and control means connected to the activating means to vary the length of the controllable-length time intervals so as to enable the minimum said interval discernible by a subject under test to be assessed.
Specification