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.

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.

Abstract: An improved vision tester apparatus and method are disclosed for use in conducting optometric examinations of patients who use video display terminals (VDTs). Specifically, the tester simulates images that are displayed to the patient by a typical VDT, so as to facilitate prescribing corrective lenses that will perform well for the patient when used with an actual VDT. The tester (10) includes a flat-panel electroluminescent light source (32) for illuminating a screen (14) without hot spots. The screen includes a colored ink layer (78,80,82) and an opaque ink mask (70) for forming pixel-like light elements (24). Lensing structures (52,56,58,60) degrade the image such that each light element exhibits a generally Gaussian light amplitude curve (FIG. 5B) characteristic of a pixel of an actual VDT. A rechargeable battery (34) coupled to a inverter circuit (30) provide portable power for the EL panel to complete a compact, portable tester.

Abstract: An optical instrument for use in conducting optometric examinations which generates an alphanumeric type display simulating the optical features of displays provided by video display terminals. The instrument comprises a light source and a multi-layered screen through which light from the source may be transmitted. The screen employs light from the source in forming characters which are comprised of pixel-like light elements similar to those making up VDT generated characters. Further, the screen is operative for degrading the image quality of the characters by transforming the light elements into Gaussian type spatial profiles typical of the pixels generated by VDTs.

Abstract: An optical instrument for use in conducting optometric examinations which generates an alphanumeric type display simulating the optical features of displays provided by video display terminals. The instrument comprises a light source and a multi-layered screen through which light from the source may be transmitted. The screen employs light from the source in forming characters which are comprised of pixel-like light elements similar to those making up VDT generated characters. Further, the screen is operative for degrading the image quality of the characters by transforming the light elements into Gaussian type spatial profiles typical of the pixels generated by VDTs.

Abstract: A simulation card for simulating the eye fatigue of a user of a display screen. The simulation card is adapted to mount in front of a lens changing apparatus. An opening in the card permits the eye doctor to examine the patients eyes while the patient focuses on images that surround the opening. A light source behind the card projects through a diffuser screen e.g., frosted "Mylar" plastic film to simulate, on the viewing screen, the images of a display screen.