Visual faculty testing apparatus

US4293200A · kind A · utility

Inventors

• John Dobson · Paris, CA
• Peter Davison · Sumner, US

Key dates

• Filing date: Mar 10, 1980
• Grant date: Oct 6, 1981
• Expiry date: Mar 10, 2000

Classification

• Technology area (CPC A): Human Necessities
• CPC primary: A61B3/063
• WIPO field: Medical technology
• WIPO sector: Instruments

Abstract

Visual faculty testing apparatus is proposed to facilitate contrast sensitivity assessment. Existing procedures are limited and involve the presentation to a subject of a target of which the overall contrast is varied to determine the minimum level at which it is detectable. The present apparatus differs by presenting a target array of light and dark areas alternating in one direction, and with the luminance of at least one set of areas varying towards that of the other set in another direction, the apparatus including control means affording adjustment of the rate of this luminance variation whereby points of minimum contrast detection can be moved across the target. The amount of adjustment for each movement to prescribed subjectively judged positions or target patterns then gives a comparative basis for contrast sensitivity. The existing procedures commonly involve successive presentation of grating targets of respectively different uniform spacial frequency, with the minimum contrast detection levels being plotted against frequency in a contrast sensitivity function characteristic, and is time-consuming. The procedure can be compacted by use of the present apparatus in a prefer…