Abstract: An image display system comprises polarization spectacles having different polarization axes with or without .lambda./4-foils of both polarization lenses forward of the eyes of the person to be tested. The system of the invention further includes an image display device for generating light with a specific direction of polarization or a specific rotational direction of the circularly polarized light. The image display device comprises essentially at least one vectograph film and at least one image screen. This arrangement can so influence the light coming from the image screen that test figures or parts thereof can be seen by only one eye or by both eyes. If the image display system is to be used as a vision testing system and the test figures are to be changed, then there is a corresponding command of a drive circuit via a memory. The drive circuit drives the image screen in a suitable manner. A color display can be provided by making an appropriate modification to the image display device.

Abstract: A patient-user interactive psychotherapy apparatus for use in Eye Movement Desensitization and Reprocessing treatment is disclosed. The psychotherapy apparatus includes a pair of visual displays, each for displaying an image having an emotional impact on a particular patient-user. The visual displays are positioned horizontally spaced from one another in the patient-user's field of view. The visual displays are each operable between two operational states including: a first operational state, wherein the image is highly, visually perceptible by the patient-user; and a second operational state, wherein the image is less visually perceptible by the patient-user. A pair of hand held switch inputs for switching between the two operational states of each visual display is also provided. In use, the patient-user alternately actuates the hand held switch inputs which causes the image to be alternately displayed as a highly, visually perceptible image in a back and forth manner on the two visual displays.

Abstract: A method and system for presenting two successive images on a video display unit as a dichoptic stimulus of substantially equal intensity, wherein a first image is displayed at a predetermined intensity so as to be seen by a first eye of an observer only, an optical shutter being used to prevent the displayed image from reaching the second eye of the observer. The first image is then extinguished and the state of the optical shutter reversed so that the first eye can no longer see the video display unit whilst a second image is presented to the second eye. In order to prevent the second eye from seeing an after image of the first image, a neutral density filter or polarizer is disposed within the light path and the second image is illuminated at a correspondingly higher intensity so as to compensate for the attenuation factor of the neutral density filter or polarizer.

Abstract: A vision screening apparatus and screening method that includes a myopic screening test image and a hyperopic screening test image. In one embodiment, each screening test image includes a test letter member superimposed on a colored background member that, in combination, form the myopic screening test image portion and the hyperopic screening test image portion. In a preferred embodiment, the myopic test image is formed by a test image member, such as a letter, superimposed on a red colored background. The hyperopic screening test image is formed by a test image, such as a letter, superimposed on a green colored background. Alternatively, the test images may be colored, while the background remains a neutral color.

Abstract: A simple and relatively inexpensive system has been developed for screening people both with normal vision and those with ocular and optic nerve disease using the Pulfrich stereo-illusion phenomenon. The system uses an audio/visual recording showing a ballerina moving in a pendulum fashion in front of a cone. The person to be tested uses a device which sequentially has no filters and filters of varying density whereby the patient with normal vision will see the ballerina moving back and forth in front of the cone and then rotating around the cone clockwise and counter-clockwise. The audio/visual recording may be shown to the person to be tested on a television set or a tv monitor.

Abstract: A vision testing system includes polarization spectacles having different polarization axes with or without .lambda./4 filters for the two polarization lenses forward of the eye of the patient to be tested. This system also includes a vision testing apparatus for generating light having a specific polarization direction. The vision testing apparatus includes essentially two polarization filters and two LCD-displays which are mounted alternately one behind the other. This arrangement can so influence the light coming from the light source that test figures or portions of the test figures can be seen by one eye or by both eyes. If a test figure is to be changed, then a corresponding command is issued via a key pad to a switching unit which drives two drive circuits of the two LCD-displays in a desired manner. By making appropriate modifications of the vision testing apparatus, a patient can be tested as to color-vision acuity.

Abstract: Apparatus for use in optometry to determine the degree of stereo acuity present in a patient comprises a frame having a proximal end adapted to engage against the face, particularly the chin of the patient, and carrying a support structure for receiving a plurality of standardized stereograms to be capable of selectively being brought into the patient's line of vision. A test procedure utilizing the apparatus is also disclosed.

Abstract: 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.

Abstract: By using a viewing device and the proper configuration of visual stimulus material, one can create competition between the two eyes and determine what is perceived by a binocular observer. Where one eye sees light or pattern in a zone of the visual field, surrounded by a dark boundary, and the other eye sees stimulus material which does not have such a boundary, the material which is contained within the dark boundary will dominate the binocular perception. With some stimulus configurations the observer will see a bright, "lustrous" form which appears to float slightly above the stimulus surface. In other cases patterns presented to each eye will be dissected and combined into a composite perception which is determined by the presence of the dark boundary. Applications for the invention include testing of patients for impairment of vision and producing special effects in movies and other forms of entertainment.

Abstract: Pre-literate children are screened for amblyopia utilizing a simple device. A pair of eyepieces are mounted by a static structure so that the fields of view through the eyepieces are segregated. A card having two different, spaced pictorial representations of common physical objects or beings is mounted to the static structure so that the pictorial representations are visible through the eyepieces. If the pre-literate child is not able to accurately report both of the different pictorial representations on the card, the child is sent for more detailed testing.

Abstract: An optical test chart for testing binocular vision. The chart has three lines of text, with the middle line printed or marked in letters or characters which have no polarizing effect. The line above this middle line is marked in letters or characters which have the effect of polarizing light reflected from them, in a plane of polarization in one direction, while the line below the middle line is similarly marked with letters or characters having the effect of polarizing reflected light but with the plane of polarization in a different direction at a substantial angle, preferably a right angle, to the direction of polarization caused by the upper line. The person whose vision is being tested views the test chart through polarizing spectacles, the spectacle in front of one eye having a plane of polarization corresponding to that of the upper line of text on the chart, and the spectacle in front of the other eye having a plane of polarization corresponding to that of the lower line of the text.

Abstract: A portable visual function tester and testing method is described for rapid and accurate measurement of several human vision parameters, including critical fusion frequency, stereopsis, Snellen visual acuity and visual resolution, cyclophoria, eye dominance, and lateral and vertical phoria, which comprises, first and second illuminated visual displays disposed for viewing by respective left and right eyes of a subject along respective parallel first and second optical axes, each display comprising an array of visual display patterns, one pattern of each display comprising a pair disposed for simultaneous viewing by the subject in the measurement of a corresponding vision parameter; the display patterns include an illuminated blinking disk for measurement of critical fusion frequency, a rectangular array of four-dot sets for measurement of stereopsis, an array of Snellen E designs of various sizes and orientations for measurement of visual acuity, and a resolution fan comprising a pattern of a plurality of rad