Spatial frequency and contrast sensitivity test chart
Method and apparatus for objective determination of visual contrast sensitivity functions
Glaucoma detection utilizing pattern discrimination test
Method and apparatus for visual-evoked responses
Diagnostic screening procedure for identifying dysmetric dyslexia
Differential diagnosis of sensory abnormalities using a normalized, ratiometric analysis of steady state evoked potentials Patent #: 4832480
ApplicationNo. 398593 filed on 08/25/1989
US Classes:600/558, Eye or testing by visual stimulus351/222, Subjective type351/239, Including test chart or target351/246Methods of use
ExaminersPrimary: Cohen, Lee S.
Assistant: Pfaffle, K. M.
Attorney, Agent or Firm
Foreign Patent References
International ClassesA61B 003/02
Foreign Application Priority Data1988-08-26 AU
AbstractExisting 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.