An optotype projector apparatus provided with variable contrast, and having a large variety of optotypes and matrices for providing tests for stereoscopic vision of chromatic balance and comprising a projector for producing contrasting variations of the optotype images operating on the basis of two complementary light sources, one provided by a primary body and the other provided by a secondary body, both of which are remotely controlled so that by diminishing the intensity of one source, a consequent increase of the other source takes place. The primary body is provided with a ferrule for controlling the movement of a guide to focus an objective lens, and the primary body emits a first light beam towards the objective lens along a first axis, the secondary body emits a second light beam along a second axis, a beam controller directs the second light beam through the objective lens along the first axis onto a specific area of the screen, and the optotypes are moved past the path of the first light beam to vary the optotype projected onto the screen, and the matrix is moved past the first light beam.

The inventive method and apparatus are based on the display of a striped target with constantly accurate contrast to the patient for finding a visual function disturbance associated with such eye diseases as glaucoma or diabetic repinopathy at their earlier stage. A sight target of striped pattern is formed on the screen having a uniform brightness, the striped target is oscillated in the direction orthogonal to the striped pattern while varying the contrast of striped target and showing it to the patient, and the threshold of the pattern contrast which can be recognized visually by the patient is measured.

A lightweight, pocket-sized, hand-held near vision test apparatus that selectively retroilluminates different near vision test objects located on an interchangeable near vision test card, or alternatively, selectively displays near vision test objects on a flat panel display screen. The apparatus allows the examiner to electronically direct the patient's attention to selected near vision test objects, while providing a baseline amount of contrast illumination.

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.

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.