Abstract: A novel contrast sensitivity test utilizing an adaptive contrast threshold algorithm is proposed. The contrast sensitivity test is embodied as a two-alternative forced choice examination using grating stimuli of randomly interleaved spatial frequencies. The stimulus's orientation is either tilted to the left or right of vertical. During an examination, a succession of grating stimuli is presented to the subject, and the subject asked to indicate the orientation of each stimulus. The contrast level for the next stimulus is varied depending on the subject's response to the previous one using an adaptive weighted up-down algorithm. For each correct response, the contrast level is reduced, whereas for each incorrect response the contrast level is increased. Importantly, the amount by which the contrast level is lowered is different from the amount by which it is raised, and as the examination progresses, the amount changes.

Abstract: A novel visual field test utilizing oscillating visual stimuli is proposed, which may be used to diagnose for eye disorders, such as glaucoma or macular degeneration. Such visual stimuli oscillate in color, polarity, saturation, luminance or intensity. Preferably, the visual test pattern consists of oscillating visual stimuli arranged in a pattern, such as a repeating or grid pattern, covering substantially all of the field of vision being tested. And, may include the use of frequency doubling visual stimuli. In use, the visual field test pattern is positioned in front of the patient so as to cover substantially all of the field of vision being tested, typically about a solid angle of 40° or more. The eye under examination is fixated, and the patient asked to indicate areas where the oscillating visual stimuli are dissimilar, such as by outlining those areas different from the rest of the visual field test pattern.

Abstract: The present invention provides a method for establishing fixation during computerized visual field perimetry, requiring the subject to fixate on a stationary target for a brief instance as he/she moves a secondary target towards the stationary target. In a preferred embodiment, the subject interactively moves the secondary target in the shape of crosshairs toward the stationary fixation target displayed on a monitor using the operations of a computer mouse. The stationary fixation target has preferably the shape of a small red circle in order to make it readily identifiable by the subject. The computer mouse pointer when contacted attaches itself to the secondary target. The subject then moves his head so that the fixation target is directly in front of him/her, and, while staring at the fixation target, moves the secondary target towards the stationary fixation target.

Abstract: A technique for evaluating the topography of a cornea is disclosed, which utilizes a virtual image/object of a keratoscope pattern. The disclosed topography system includes a structured light source to create the keratoscope pattern or another diagnostic pattern, an optical assembly to focus the created pattern upon or behind the cornea, and for capturing the image reflected off the patient's eye and directing the reflected image toward an imaging system for processing. Light emitted by the light source is preferably not in the visible range, to minimize discomfort to the patient. Since the topography is evaluated with a projected virtual image, there is no nose or brow shadow, thereby allowing better corneal coverage. The optical system includes an aperture stop which is preferably conjugate with a point behind the corneal surface approximating the center of a normal cornea.

Abstract: A novel psychophysical visual test based on the visual response of the eye to alternating chromatic complementary colors or achromatic grays of varying saturation, luminance and/or contrast is proposed for the early detection of glaucoma, and other diseases. In one embodiment, although the luminance level remains constant, the visual stimulus alternates between two complementary or counter phase colors, preferably against a gray background at about 40 times a sec, for example, between blue and yellow. When the colors are alternated in this manner, the visual stimulus appears white or gray to an observer, instead of either blue or yellow. As the saturation is reduced, however, the alternating colors appear grayer, and then eventually cannot be perceived. Persons suffering from glaucoma and other diseases, however, find it more difficult than normal people to distinguish the visual stimulus as the saturation and/or luminance is reduced.