Abstract: An apparatus for testing twilight vision and blinding sensitivity includes a housing having openings in opposite sides thereof, a person to be tested being able to look through the housing along a line of sight extending through both openings. A filter is provided for one of the openings to limit external light entering such opening. A concave mirror is arranged in the housing with its optical axis normal to the line of sight, and a semi-transparent mirror is arranged at the intersection of and at 45.degree. angles with respect to the line of sight and the mirror optical axis. A screen arranged at the focal point of the mirror is simultaneously illuminated by two projectors, a test figure being arranged in the beam of one projector and the light intensities of the two projectors being inversely proportionally controlled. Two filters are provided which can each be inserted in the beam of a respective one of the projectors to further reduce the light intensity.

Abstract: An optical testing and exercising device including a stereo film viewer having a pair of eyepieces and one or more lenses which can be interposed along the user's line of sight to change the apparent distance of an image. The viewer also includes a housing with a pair of juxtaposed eyepieces and an opening to receive a film having a series of frames bearing images to be viewed. A frame advancing mechanism advances successive frames of the film into the line of sight of the device for viewing by the user through the juxtaposed eyepieces. The frame advancing mechanism also changes one or more lenses mounted in the housing between the eyepieces and the film receiving opening into the viewer's line of sight. The interposed lenses can be utilized for various effects, such as to change the apparent distance of the image from the viewer, thus causing the eye muscles to be exercised.

Abstract: A compact refraction instrument for use in both the objective and subjective examination of human eyes. The instrument incorporates an alignment mode, a retinoscopy mode, a distance mode and near mode. For carrying out the functions associated with these modes, the instrument includes a Brewster stereoscope and a system for supporting a plurality of binocular/monocular vision testing slides. Positioned along the pair of optical paths between the Brewster stereoscope and the slide supporting system are: a first mask/septum system; a mode change system; a second mask/septum system; and a horizontal/vertical target mask system. The instrument also includes a refractor system and apparatus for suspending the refractor system in the optical paths before the Brewster stereoscope. The slide supporting system includes two rotatable concentric drums. Each drum is formed from a plurality of vision testing slide holders supported between a pair of ring gear members. The drums are supported by at least two shafts.

Abstract: The apparatus and method comprise means to evaluate the interocular latency difference known to exist in individuals afflicted with multiple sclerosis. The apparatus includes two horizontal rows of 10 light emitting diodes separated by a horizontal partition. The upper row of diodes is seen by the eye and a lower row of diodes is seen by the other eye. Although the two rows are separated vertically, they are made to overlap optically and appear as one row by means of two periscopic eye pieces. The ten diodes in each field of view are energized (strobed) sequentially for 1/10 of the time required to scan a horizontal row. The directions of scanning in the two rows are opposite to each other. A separate diffraction line ruling is placed in each optical path to produce elongated diffraction images of each energized diode in one row which are at 45 degrees to the horizontal and at right angles to the elongated diodes in the other row.

Abstract: An apparatus for measuring torsional rotation of an eyeball about the visual axis by means of an afterimage. The apparatus includes a frame mountable to a patient so as to be fixed with respect to the patient's skull. Mounted on the frame are means for creating a transitory bright image to imprint the retina of the patient's eye with an afterimage and means for creating a target image alignable with said afterimage. Measuring means is included in the apparatus so as to indicate the angular displacement of the target image relative to a preset reference position corresponding to a different stimulus condition. In the preferred embodiment, the apparatus is a tubular assembly supported by a bite bar.