Importance

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Abstract

A test card for use in eye examinations emulates the light return profile of a video display screen such as those commonly used in connection with computers. The test card is used for prescribing corrective lenses for a computer user. The test card is formed on an opaque planar medium and has a plurality of characters formed thereon for reading by the patient, each character formed by a plurality of pixel elements. The pixel elements may be formed by designing a pattern of dots on a computer system using graphic software for representing the resulting pattern in a machine-readable graphics file. The graphics file is used to control a compatible imagesetter machine for forming the desired pattern on photographic film. According to an alternative method, a film master is prepared in which each pixel is a solid black dot. The test card is prepared by printing the image onto photographic paper through a diffusion element so as to create an approximately Gaussian light return profile across each pixel.

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First Claim