| 摘要 |
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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