Visual faculty testing apparatus Patent #: 4293200
ApplicationNo. 06/394040 filed on 06/30/1982
US Classes:351/205, Objective type351/211, Including projected target image351/243, Illuminated600/544, Detecting brain electric signal600/558Eye or testing by visual stimulus
ExaminersPrimary: Bovernick, Rodney B.
Attorney, Agent or Firm
International ClassesA61B 3/02 (20060101)
A61B 3/06 (20060101)
A61B 3/09 (20060101)
A61B 5/0476 (20060101)
A61B 5/0484 (20060101)
AbstractA method and apparatus for objectively determining the visual contrast sensitivity function of a human subject involves subjecting the vision of the human subject to a plurality of sine wave gratings differing in spatial frequency and contrast levels. As the subject views the grating patterns on a video monitor, the brain wave activity of the subject is detected and steady state Fourier spectra of the activity are recorded. In each spectrum corresponding to a grating pattern of a particular spatial frequency, a visual evoked potential component may be distinguished from noise by adjusting the contrast level of the grating pattern. A contrast threshold used in deriving the visual contrast sensitivity function is identified for each grating pattern of a particular spatial frequency by pinpointing the contrast level at which the visual evoked potential component becomes indistinguishable from noise in the spectrum.