Method for use in diagnosis of glaucoma
First Claim
1. A method of testing a person to determine the presence of glaucomatous destruction of ganglion cells in a retina of that person, said method comprising the steps of:
- (a) monocularly presenting the person with a sinusoidal grating pattern having generally elongate striations, the contrast of the pattern being modulated at a frequency in the range of from about 10 Hz to about 50 Hz, the contrast of the grating pattern being such that the person can observe a frequency-doubled grating pattern;
(b) reducing the contrast of the grating pattern until a contrast value at which the frequency-doubled pattern is no longer observed is attained; and
(c) comparing said attained contrast value at which the frequency-doubled pattern is no longer observed with the highest contrast value at which the frequency-doubled pattern is no longer observed by persons of normal vision.
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Abstract
Existing techniques for diagnosis of glaucoma, namely observation of a scotoma, measurement of intraocular tension and assessment of color vision defects have drawbacks. The present invention overcomes those drawbacks by a psychophysical test in which a sinusoidal grating pattern is presented to a subject with the contrast of the pattern modulated at a frequency in the range from about 10 Hz to about 50 Hz, so that the subject can observe a frequency-doubled pattern of the grating. The contrast of the pattern is then reduced until a threshold value is reached, at which value the frequency-doubled pattern is no longer observed. The threshold value is then compared with the threshold value for persons of normal vision. A higher than normal threshold value indicates that the subject may be suffering from glaucoma. Persons with well-developed glaucoma have threshold values that are approximately twice the threshold value of a person with healthy vision. The pattern is conveniently established on the screen of a cathode ray tube, controlled by a programmed microprocessor.
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8 Claims
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1. A method of testing a person to determine the presence of glaucomatous destruction of ganglion cells in a retina of that person, said method comprising the steps of:
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(a) monocularly presenting the person with a sinusoidal grating pattern having generally elongate striations, the contrast of the pattern being modulated at a frequency in the range of from about 10 Hz to about 50 Hz, the contrast of the grating pattern being such that the person can observe a frequency-doubled grating pattern; (b) reducing the contrast of the grating pattern until a contrast value at which the frequency-doubled pattern is no longer observed is attained; and (c) comparing said attained contrast value at which the frequency-doubled pattern is no longer observed with the highest contrast value at which the frequency-doubled pattern is no longer observed by persons of normal vision. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification