COMPUTER DISPLAY SCREEN SIMULATION FOR OPTOMETRIC EXAMINATION

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.