Patent Document ID: 5500699
Application ID: 08400913
Patent Status: 1

Claim One:
1. Vision sensitivity evaluation apparatus including: means for presenting a perceivable multiplicity of distinctly separated information areas; each of said information areas comprising successively dimmer regions between successive edges of said information areas, the regions of which have a substantially linear character and the contrast level and/or spatial frequencies or size of occurrence of which differ in different information areas; the edges of each information area successively tapered in said contrast level and/or frequency and/or size of occurrence to approach the level of a surround; the surround of said information areas having a value of mean luminance which tapers to the mean luminance of the information area being interrogated; indicia immediate the boundary of the location of each information area against said surround for indicating to the subject or system being tested the location of the information area for interrogation; and whereby successive information areas are presented in a range of contrasting luminance and spatial frequency or size of occurrence therein of the light and dark regions which upon observation by a person or system may be used as an accurate basis for determining the sensitivity and range of perception.