Abstract: An automatic perimeter wherein the eye to be examined is maintained in a predetermined position to look at an eyepiece which focuses enlarged images of a series of stimuli on the retina. Stimuli are presented by a light emitting diode in combination with a diaphragm and are projected into selected locations around the optical axis of the eye. The perimeter operates without a cupola and is further provided with a system for illuminating the area in front of the eye as well as with a camera which images the eye onto the screen of a monitor so that the person in charge can ascertain whether or not the eye is focused upon a reference point on the optical axis of the eyepiece.

Abstract: A visual function tester with binocular vision testing capabilities is disclosed, which includes a video display monitor and optical means, such as stereo vision glasses, to control the patient's viewing of the display. The opening and closing of the apertures of the glasses is synchronized to the display of a variety of visual acuity images. Certain images are made visible to each eye but not visible to the other, and certain images are displayed such that they appear out of the plane of the images. Methods for use of the apparatus are also disclosed.

Abstract: A method is disclosed for measuring glare-induced vision blockage in a subject, as are apparatus for performing the method. According to the method, a glare-inducing light is shined in the subject's eyes. A series of visually-perceivable patterns of varying apparent sizes, each pattern arranged around the light, is presented to the subject. Each pattern comprises a sequence of alternating light and dark segments. The pattern is preferably in the form of a broken outline of a circle centered on a window through which the glare-inducing light passes. For each pattern presented, the subject is asked to indicate which if any dark segments he perceives. The subject may also be asked how many dark segments he sees and in what locations. The smallest pattern whose dark segments can be perceived by the subject indicates the size of the subject's glare-induced vision blockage.

Abstract: An optical instrument for use in conducting optometric examinations which generates an alphanumeric type display simulating the optical features of displays provided by video display terminals. The instrument comprises a light source and a multi-layered screen through which light from the source may be transmitted. The screen employs light from the source in forming characters which are comprised of pixel-like light elements similar to those making up VDT generated characters. Further, the screen is operative for degrading the image quality of the characters by transforming the light elements into Gaussian type spatial profiles typical of the pixels generated by VDTs.

Abstract: A method and optometer apparatus for measuring the accommodative state of eye of a subject is disclosed. In a preferred embodiment, the optometer apparatus includes: a pinhole aperture plate having a center and a plurality of apertures in the pinhole aperture plate for viewing by the subject's eye; a positive lens disposed near the pinhole aperture plate and having an optical axis coincident with the center of the pinhole aperture plate; and scaled means inclined away from the positive lens for indicating to the subject the accommodative state of the subject's eye in diopters.

Abstract: The apparatus serves for triggering optically evoked responses in the patient, and the response is acquired by means of a measuring equipment. The apparatus comprises a stimulation signal generator having a surface on which an optical stimulation signal is displayed, a waveguide having a first end and a second end, a first lens system for imaging the signal on the surface into the first end of the waveguide, a second lens system arranged at the second end for imaging the image at the second end onto a presentation surface and a mount for mounting the second lens system and presentation surface a fixed distance from the patient's eyes. In order to reduce possible magnetic interference with the measuring equipment, at least the mount, the second lens system and the waveguide are formed of non-magnetic material.

Abstract: In a preferred embodiment, the optometer apparatus includes: a pinhole apure plate having first and second horizontally positioned apertures disposed on opposite sides of a first optical axis; first and second orthogonally-oriented polarizing filters respectively covering the first and second horizontally positioned apertures; a positive lens having an optical axis on the first optical axis and being positioned at a distance of approximately one focal length from the pinhole aperture plate; a lens system having an optical axis on the first optical axis; a slit aperture plate having a vertical slit and being disposed on the first optical axis and between the positive lens and the lens system; third and fourth vertically positioned polarizing filters selectively disposed adjacent to the slit aperture plate to divide the slit vertically, the third and fourth polarizing filters being respectively oriented parallel to the first and second polarizing filters; a monochromatic light source for propagating light along

Abstract: A foveal vision evaluation instrument and procedure enables a precise evaluation of the visual function of the fovea centralis (macula) area of the retina. A foveal profile is developed to document the presence and state of foveal degeneration manifested by foveal segmentation and incremental changes and abnormalities in foveal vision, such as are caused by age related macular degeneration.Beam source optics 10, beam polarization optics 20 and image selection system 30 provide a polarized projection beam PPB that transmits an image array obtained by directing one component of polarized projection beam PPB through an image transparency IT. Image element blanking optics 40 enables the individual elements of the image array to be selectively blanked using a multi-cell electro-optic shutter 45.

Abstract: A visual deficiency screening system (8) includes a display (14) and a means (10, 18) for generating a series of randomly differing images (12). A hood (24) and eyepiece (26) are provided for properly positioning a test subject relative to the display (14).

Abstract: A visual acuity testing system includes a patient video display operated under control of a compact control unit which is located adjacent the phoropter used in acuity testing. The control unit and phoropter are located in a common operating area, thus eliminating the need to shift from one position to another to operate different devices during visual acuity testing. The control unit operates in conjunction with a graphics interface processor to provide random character generation, variable character contrast, duochrome testing, automatic timing of character display, audio prompting and generation of complex test patterns such as an astigmatic clock pattern. The use of high resolution bit-mapped and vector graphics generation techniques maximizes the quality of character displayed on the patient display unit.

Abstract: To provide for an easy and accurate color vision tester, a plurality of yellow, red and green lights are mounted, or projected, onto a display, with the yellow lights providing for the background luminance while the red and green lights providing for a mixture of red and green luminance. Different patterns on the display are formed by a combination of the red and green lights. A particular pattern can be selected from among the various patterns by a pattern select circuit. The intensity of the red to green lights can be inversely varied so that different ratios of intensity for the selected pattern may be presented to an observer. Each of these ratios corresponds to a certain type of color vision. Therefore, by determining whether an observer is able to discern the pattern from the background in a particular intensity setting, the type of color vision an observer has can easily be ascertained.

Abstract: A fixation sight apparatus for an ophthalmological instrument is disclosed. It has a unique arrangement including light source and mirrors for presenting a plurality of fixation mark images on a measuring optical axis. An eye to be tested selectively fixedly gazes at the most clearly sightable one among the plurality of fixation mark images according to the sight confirmation characteristic thereof.

Abstract: A method of separating an oscillatory potential wave from an electroretinogram of a subject which contains an "a" wave, a "b" wave and said oscillatory potential wave that overlap each other. The electroretinogram ([1]) is produced by light stimulation to the retina of an eye of the subject, and is detected by a suitable device. The peak-to-peak distances of the detected electroretinogram are determined, and a mean period (T) of the oscillatory potential wave ([10]) to be separated from said electroretinogram is obtained. Then, a tentative start point (A) of the oscillatory potential wave is determined, and an OP-free waveform ([7], [9]) free of said oscillatory potential wave is obtained by obtaining moving averages of a first intermediate waveform ([6], [8]) which is determined based on the electroretinogram and the determined tentative start point (A). The oscillatory potential wave ([10]) is extracted by subtracting the OP-free waveform ([7], [9]) from the electroretinogram ([1]).

Abstract: A device for detecting localized retinal damage derives focal responses of the retina from the global response of the retina to patterned stimuli in one's visual field. The stimuli comprises a series of patterns which spatially vary according to a function of a family of orthogonal functions. Each pattern also varies temporally either by being flashed before the patient or by being reversed in contrast at a fixed frequency. An electroretinogram (ERG) or magnetoretinogram (MRG) response of the patient's eye to the series of patterns is fed back into a computer generating the patterns. The responses are used by the computer to determine the coefficients of the transform of the function of the retinal response. The computer calculates the inverse transform associated with the orthogonal functions and provides the retinal response as a function of position on the retina. Contrast, intensity and temporal frequency of the patterns are chosen for a linear response of the eye.

Abstract: Glare testing apparatus enclosed in a housing includes multiple discrete light sources for creating a glare condition in the field of view from an individual being tested to a target, and provision is made for selecting the location or locations of active glare sources, which includes a centrally located source of headlight glare, and a plurality of peripheral sources which can be energized selectively or collectively. Provision is also made for adjusting target luminance, glare intensity and the apparent distance between the target and the eye position in order to test near and far visual acuity under varied conditions of luminance and glare.

Abstract: An anomaloscope for testing the human color sense which includes an optical device for producing a stimulus field including a red/green light mix and light of a yellow spectral color, a device for the mixing of the spectral colors green and red by apportioning them, such that upon strengthening one of them, the respective other one is reduced correspondingly. The anomaloscope further includes intensity control and indicating means for the spectral colors as well as for the portions of green and red determining the anomal quotient. For mixing the red and yellow spectral colors and for creating the stimulus field with a red/green light mix and a field of yellow spectral color, there is provided a partially translucent beam-splitting device arranged at approximately 45.degree. relative to the optical axis of the anomaloscope. The first spectral color yellow and the second spectral color (green or red) illuminates from one side the beam-splitter plane approximately parallel to the optical axis.

Abstract: A brightness acuity tester to assess functional visual acuity in bright light conditions and to test for recovery of visual activity after photostressing the retina is disclosed. The tester essentially comprises a device closed in one direction and open in an opposite direction, an aperture provided in the device, a source of illumination mounted within the device, a plug designed removably to be positioned in the aperture to seal the same, and a power source coupled to the source of illumination via a switch. Preferably, the source of illumination is provided with anintensity control and the power source with a voltage regulator. Preferably, the device comprises a reflector having diffusely reflecting characteristics. Preferably, the power source is a battery, making the tester a hand-held one.

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: A system for examining the color vision response of a human being utilizes substantially identical multicolor LEDs to function as reference and comparison color light sources. In one embodiment, the colors emitted by the LEDs are controlled by respectively associated voltage dividers. The voltage divider which cooperates with an LED to produce a reference color, is provided with a switching arrangement whereby one of a plurality of reference color compositions can be selected. The comparison color light is controlled by a voltage divider which is substantially continuously adjustable.

Abstract: A hyperacuity testing instrument is adapted to evaluate visual function by selectively changing the relative position of two spots or points of light that function as visual stimuli for observation by a patient. The instrument includes a laser that emits a single beam of light that is split into two beams when it passes through a bi-prism. The beams of light are visually shown as two spots on a display screen for recorded perception by a patient. A rotary adjustment selectively varies the rotational positions of the spots relative to each other whereas a linear adjustment selectively varies the separation gap between the spots. The recorded data enables a surgeon to determine whether corrective surgery to remove an ocular media opacity will, in fact, improve vision, i.e., the test procedure "penetrates" the opacity to assess visual function at the retinal-neural level.

Abstract: An optical instrument and method for measuring susceptibility to glare of a human vision system is described which comprises a glare light source of preselected intensity sufficient to generate glare in the vision system of a subject, an acuity target having first opaque or partially transparent areas and second translucent areas defining a pattern of recognizable indicia on the target, a housing supporting target and source side-by-side for simultaneous viewing by the subject, and a reflective surface within the housing for directing light from the source onto the back surface of the target for substantially uniform transillumination of the target with light from the source. Optional optical filters may be placed between the source and subject, target and subject, or source and reflective surface, for selectively filtering light viewed by the subject. A movable cover plate may be included for selectively exposing the source to the subject in certain glare susceptibility measurements.

Abstract: A vision tester having a casing horizontally adjustable with respect to a base. Inside the casing a rotating drum has a first end rotatably fixed to the casing and a second end unconnected to the casing and having an open portion. An illumination device is removably mounted to the casing and inserted inside the rotating drum through the open portion. The illumination device provides illunination to a plurality of test slides mounted to the surface of the rotating drum. A viewing device is mounted to the casing and provides left and right lenses simulating a far vision of the illuminated test slide. A pair of near vision lenses is rotatably mounted inside the viewing device and may be rotated to overlap the far vision lenses to simulate a near vision of the test slide. Peripheral vision is tested by light provided from an illumination source through fiber optic cables to peripheral vision test locations on the viewing device.

Abstract: The present invention relates to a device for detecting and/or measuring visual deficiencies in which an image observable by a patient presents several series of test signs, each corresponding with one of the various levels of visual acuity, wherein each sign corresponding to a level of visual acuity is associated to a reference sign corresponding to a lower level of visual acuity and wherein frame 1 contains signs corresponding to a visual acuity of 1/10, another frame 2 to 2/10 and following frames correspond to visual acuities ranging by steps of 2/10 respectively from the value 4/10 to the value 10/10.

Abstract: An ocular position measuring apparatus comprising a pair of fixation marks capable of emitting visible flickering beams for being watched by patient, a first pair of half mirrors positioned between the patient's eyes and the marks and an observing system for observing images of the patient's eyes on produced by light beams reflected by the half mirrors.

Abstract: An automatic optometer provided with a first visual target for measuring the visual power of a subject, a response input unit for the subject to input a response corresponding to the visual target, a control unit for determining the accuracy of the subject's response input and for presenting additional different visual targets, a counter, the counter being reset each time a visual target is presented, a comparison unit for comparing the output of the counter with a predetermined value, and request means for requesting the subject's response input in accordance with the output of the comparison unit.

Abstract: A novel optical device and method for measuring intraocular light scatter in a human vision system of a subject is described which comprises first and second light sources of respective predetermined intensities, the images of which are optically folded along a common optical axis and projected into the vision system of the subject, the first source being of intensity sufficient to generate intraocular haze in the vision system of the subject, the second source being movable in a plane substantially perpendicular to the axis along which its image is projected whereby the second source image as viewed by the subject may be selectively viewed with respect to the first source image to measure the apparent peripheral extent of the haze surrounding the first source image.

Abstract: In an apparatus for assessing visually-evoked response, wherein stimulus means are provided to present a variable visual pattern to an observer and analyzing means are provided to analyze scalp potentials of the observer responsive to said pattern; the improvement wherein the stimulus means comprise means for temporal modulation of the pattern at a determined rate and simultaneously sweeping another visual parameter, in a determined period, in a range which crosses an observer's visual threshold for said other parameter, said analyzing means comprising means for synchronously demodulating said scalp potentials employing said determined rate of the temporal modulation as a reference, at a plurality of different phases with respect to said reference, for producing a display of the scalp potentials demodulated with different phase reference.

Abstract: The present invention psychophysically detects earliest signs of loss of vision due to nerve loss in glaucoma and ocular hypertension. An instrument employs a dynamic random dot background field and a movable target that consists of a circular area in which the dots are spatially and temporally coherent. Thus, visual fields will be based on pattern discrimination rather than on conventional measures of luminance discrimination.

Abstract: A G force acceleration effects monitoring apparatus involving a pair of LED or other visual stimulus arrays, one randomly patterned by an electronic driving apparatus and one patterned by the manipulation of a G force test subject. The electronic driving apparatus preferably includes a sum of sines algorithm and the test subject manipulations are received preferably from a joystick controller. Mounting of the apparatus in a centrifuge gondola and also in off-line training stations and use of the invention by animals are also disclosed.

Abstract: A novel instrument and method for measuring the accommodative amplitude and speed of the eye of a subject is described. The instrument for making the measurements according to the present invention comprises a pair of illuminated or luminous visual displays disposed for viewing along an optical axis, the images of the displays superimposed upon each other for viewing by a subject, one of the displays comprising a pattern having a plurality of distinct and recognizable orientations with respect to the axis along which it is viewed, an orientation generator for randomly and alternately generating one of the orientations for viewing by the subject, a switch operable by the subject for turning the displays off and indicating the observed orientation of the random pattern, and a recorder for recording the last displayed orientation and the time the displays were on or the time between presentation of one display and the correct identification of the other.

Abstract: A novel vision test device and method for measuring the ability of a subject to perceive contrasts is described, which comprises a chart for display to the subject having a plurality of visual test shapes systematically organized thereover in a predetermined array on a background of preselected luminance or reflectance level, each test shape having a preselected luminance level providing maximum contrast relative to background at its center and substantially zero contrast relative to background at its edges, the luminance (or reflectance) level of each test shape varying radially from its center outwardly according to a Gaussian distribution of preselected distribution factor.

Abstract: A novel device and method for determining the contrast sensitivity of a subject is provided and comprises a test chart including a plurality of patches systematically organized in a predetermined array, each patch having a plurality of adjacent patterned areas, at least one of which is a pattern of alternate light and dark regions of predetermined contrast, and the remaining patterned areas are solid gray patterns of predetermined reflectance, each contrast pattern being characterized by a space average reflectance equal to the predetermined reflectance value of the adjacent gray patterned areas. The spatial frequency and contrast of the alternate dark and light regions may be varied in the array of patches. In the method for determining the visual contrast sensitivity of the vision system of a subject, a chart of the invention is displayed to the subject at successively shorter distances, and the greatest distance at which the subject can resolve each contrast pattern is determined and recorded.

Abstract: The present invention relates to an apparatus for eye sight examination, allowing to test both of the patient's eyes, especially to detect his common failures and vision defects, for far and close vision, and eventually intermediary distance vision.The test-image are borne by at least one ribbon or band mounted in a block of two winding spools, housed in a body forming an easily removable tape box of an adequate support of body of the apparatus.The invention applies to the automatic or semi-automatic detection of visual defects of a patient.

Abstract: A simulation card for simulating the eye fatigue of a user of a display screen. The simulation card is adapted to mount in front of a lens changing apparatus. An opening in the card permits the eye doctor to examine the patients eyes while the patient focuses on images that surround the opening. A light source behind the card projects through a diffuser screen e.g., frosted "Mylar" plastic film to simulate, on the viewing screen, the images of a display screen.

Abstract: Apparatus for displaying eyesight tests for patients comprising a viewing station a test support having a plurality of eyesight tests selectively visible from the viewing station along first and second optical paths, the first optical path being for near vision and devoid of optical focusing means and the second optical path being for far vision and having optical focusing means. The optical paths have a common section running from a selected test support panel. Each of the optical paths comprises a mirror for bending the viewing axis toward the viewing station, the mirror for the first optical path being rockably mounted or semireflecting for providing access to the second optical path.

Abstract: A novel vision tester and vision testing method is described which comprises a pair of translucent displays, each transilluminated by electroluminescent lighting panels, the images of the two patterns being superimposed to provide a combined image characterized by a pattern of variable contrast. Light sensors near each light panel provide a measure of the relative intensities of the two images, which provides a measure of the contrast of each combined image. Contrast may be directly read out by processing the signals from the light sensors. The tester may be battery powered for portability.

Abstract: The invention refers to an arrangement for the carrying out of eye examinations by means of an optotype mask which is illuminated from behind. It consists therein that the optotype mask is arranged in front of the picture screen of a video tube which serves as source of illumination and that means are provided by which the picture-screen presentation can be controlled with respect to brightness, color, contrast, partial or full surface illumination and blending-in of additional static or moving structures in order to carry out different eye tests. In this connection the optotype masks may be exchangeable or be moved over the picture-screen surface by a mechanical drive between different eye tests. Furthermore, the optotype mask may consist of flexible material which may be moved past the surface of the picture screen between different eye tests.

Abstract: A visual examination apparatus for administering a photostress recovery test. The photo pigments of the cones of the subject eye are conditioned to a steady state by exposure to a dim light which retro-illuminates an optotype. The size of the optotype is related to the visual acuity of the subject eye. A bright light source of repeatable duration and intensity and spectral distribution of energy is directed to bleach the photo pigments of the cones of the macula. A common switch triggers the flash and starts a digital timer. After the flash, a different optotype of the same size as the initial one is substituted therefor. When the subject eye recovers from the dazzling flash sufficiently to detect the different optotype, the timer is stopped. The length of time required for the cones of the macula to regenerate photo pigment is dependent upon whether the cones are normal and on their apposition to the retinal pigment epithelium.

Abstract: A method is provided for testing the ability of a subject to visually perceive contrast between adjacent fields of different luminance. The subject is presented with a series of visual test patterns, each one of which includes at least two fields of differing luminance resulting in a contrast edge at the interface between the fields. The subject's ability to perceive the edge between the fields is monitored. A series of different test patterns are presented electronically to the subject on a computer-controlled screen which includes one field of constant or fixed luminance and one field of variable luminance. The luminance level of the variable field may be predetermined and varied by the computer in one protocol or controlled by the subject using a subject operated control device as an alternative protocol.

Abstract: This invention involves measurement of the visual contrast sensitivity (modulation transfer) function of a human subject by means of a linear or circular spatial frequency pattern on a cathode ray tube whose contrast is automatically decreasing or increasing depending on the subject pressing or releasing a hand-switch button. The threshold of detection of the pattern modulation is found by the subject by adjusting the contrast to values which vary about the subject's threshold thereby determining the threshold and also providing by the magnitude of the contrast fluctuations between reversals some estimate of the variability of the subject's absolute threshold.

Abstract: A method and apparatus for objectively determining the visual contrast sensitivity function of a human subject involves subjecting the vision of the human subject to a plurality of sine wave gratings differing in spatial frequency and contrast levels. As the subject views the grating patterns on a video monitor, the brain wave activity of the subject is detected and steady state Fourier spectra of the activity are recorded. In each spectrum corresponding to a grating pattern of a particular spatial frequency, a visual evoked potential component may be distinguished from noise by adjusting the contrast level of the grating pattern. A contrast threshold used in deriving the visual contrast sensitivity function is identified for each grating pattern of a particular spatial frequency by pinpointing the contrast level at which the visual evoked potential component becomes indistinguishable from noise in the spectrum.

Abstract: An improved eye testing apparatus is provided which permits the operator thereof to precisely and clearly designate certain characters of the eye test pattern. The device includes an external stage, a duplicate test pattern on the stage, and a mask having separate designation locations for designating a character of the test pattern at a vision station within the device while simultaneously designating an identical character of the duplicate test pattern.

Abstract: A vision testing system is disclosed in which a collimated beam of coherent light waves is passed through a transparency of an object such as a grating, a Snellen letter or a portrait to produce the diffraction pattern of the object. Then the light waves forming the diffraction pattern pass through a lens to produce the Fourier transform (the diffraction pattern) at the focal plane of the lens. A variable spatial frequency filter is positioned at the focal plane. Then the spatially filtered light waves are passed through a second lens to produce the inverse of the Fourier transform at the image plane of the second lens. That image is the spatially filtered object. By varying the degree and type of spatial filtering the resultant image can be used to test for contrast sensitivity or character (object) recognition.

Abstract: A perimeter for testing visual field light-sensitivity presents a moving spot or a set of fixed spots visually to a patient. The spot or spots have ill-defined edges so that the effect of visual acuity is minimized. A hand-held device is proposed whereby mass monitoring, particularly for the effects of glaucoma, is possible.

Abstract: A Friedmann analyser wtih an arrangement of fixed and rotatable shutters for displaying different patterns of light spots to a subject has a screen for displaying to the operator each light spot pattern selected by illumination of a series of light-emitting elements at fixed positions over the screen area. The light-emitting elements are actuated by a fixed array of infra-red emitting and receiving elements that direct radiation onto a binary-coded reflective pattern displaceable with the rotatable shutter and sense the radiation reflected by said pattern so that with the displacement of the shutter different reflected code signals are sensed associated with respective shutter light patterns displayed to the subject.

Abstract: A vision testing device, wherein projected or transilluminated indicia in the form of characters and/or symbols of different sizes and recognizabilities are shown to a subject under a test in a test field. The characters or symbols appear bright with a luminance of preferably about 70 cd/m.sup.2. A darker field surrounds the characters or symbols, with the darker field having a luminance of about one-fifth to one-eighth of the luminance of the characters or symbols. Brighter areas with a luminance of 250-1000 cd/m.sup.2 are provided adjacent the darker surrounding field.

Abstract: A method and apparatus for increasing visual acuity of a person wherein a target is selectively moved toward or away from the person to different positions at accurately determined distances therefrom. At each of the positions, the person is required to identify the appearance of the target which is randomly changed to any one of a plurality of different appearances. The concept includes the moving of the target further away from the person whenever the identification of the target appearance is correct at a given position and moving the target closer to the person whenever the identification is incorrect. The invention comprehends moving the target incrementally at smaller distances away from the person than toward the person. A Badal lens is interposed between the person and the target for causing the focal points to be at the nodal point of the eye of the person.

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. The mode change system includes a first mirror for folding the optical paths when the instrument is used for subjective testing at a distance and near vision testing.

Abstract: An apparatus for testing glare susceptibility of a subject. A planar member having an opaque target is surrounded by a contrasting surface which is surrounded by a translucent surface. Light is directed to one side of the planar member and the subject's ability to see the target against the contrasting surface against a glare of light through the translucent surface determines the glare susceptibility of the subject.

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