Determination apparatus for contrast threshold of visually impaired

摘要

The apparatus includes a device for setting the optical test objects in different presentation positions. An optical test disc with several test objects is rotated by a motor driven system, and generates and sets continuous contrast values. An optical test object is presented to the patient at random. A microcomputer system with software generates and sets continuous contrast values with respect to red-weak-sightedness or red-blindness. Two coupled optical test discs are used to set continuous brightness values, and a screened light source is used to measure the contrast under standardised back-lighting conditions. The re-adaptation time is measured after being exposed to glare.