The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 29, 2004
Filed:
Mar. 12, 2002
Jeffrey L. Stewart, Greenwich, CT (US);
Stewart Weiss, Jackson Heights, NY (US);
Visionrx, Inc., White Plains, NY (US);
Abstract
A novel contrast sensitivity test utilizing an adaptive contrast threshold algorithm is proposed. The contrast sensitivity test is embodied as a two-alternative forced choice examination using grating stimuli of randomly interleaved spatial frequencies. The stimulus's orientation is either tilted to the left or right of vertical. During an examination, a succession of grating stimuli is presented to the subject, and the subject asked to indicate the orientation of each stimulus. The contrast level for the next stimulus is varied depending on the subject's response to the previous one using an adaptive weighted up-down algorithm. For each correct response, the contrast level is reduced, whereas for each incorrect response the contrast level is increased. Importantly, the amount by which the contrast level is lowered is different from the amount by which it is raised, and as the examination progresses, the amount changes. A maximum likelihood method is then employed for finding the best estimation of the contrast threshold from the subject's responses to known contrast levels.