Abstract: An eye chart presentation device includes a display to display an eye chart image on a screen, a reflection mirror to reflect light flux emitted from the display, and a convex lens system to form a virtual image of the eye chart image from the light flux reflected by the reflection mirror, the focal length of the convex lens system being greater than 800 mm. The screen is positioned within the focal length of the convex lens system, and the display emits the light flux from a lateral direction with respect to sightline of the eye. The reflection mirror includes a first mirror to directly reflect the light flux from the display and a second mirror to reflect the light flux reflected by the first mirror to the convex lens system.

Abstract: A pixel light source apparatus, system and method are disclosed for a stimulus source for visual pathway testing. A representative system includes a plurality of pixel light sources and a control and driver circuit. The pixel light sources are coupled to each other to form a partially-spherical dome, with each pixel light source arranged to emit light directed to a convergent location of the partially-spherical dome. The control and driver circuit implements a selected stimulus protocol to selectively energize each pixel light source to generate light stimulation to any arbitrary or selected portion of the retina of an eye of a human subject. A representative pixel light source comprises at least one elongated and optically opaque side wall; a rear wall; an illumination source; a first optical element defining a first light chamber; and a second optical element defining a second light chamber.

Abstract: A head mounted display includes a lens disposed at a position facing a user's cornea; a plurality of infrared light sources disposed in a periphery of the lens that emit infrared light toward the user's cornea; a hot mirror that reflects the infrared light; a camera that captures an image projected into the hot mirror; an output unit that outputs an image captured by the camera to an eyesight direction detection unit that detects an eyesight direction of the user; and a housing, wherein when the periphery of the lens is divided into four regions: a first corresponding to the outer corner side of the eye, a second corresponding to the inner corner side, a third corresponding to the top side of the head, and a fourth corresponding to the jaw side, the plurality of infrared light sources are disposed in any of the first region and the second region.

Abstract: A method for interactive adjustment of a parameter of a continuously variable optical lens involving having a subject view an eye chart through a variable lens frame comprising at least one continuously variable optical lens, applying a modulation to a selected parameter of said continuously variable optical lens around an average value, and tuning said average value by minimizing the flickering visible to the subject and due to the modulation.

Abstract: This invention relates to a method for providing markers for evaluating and/or practicing the visual field recognizable by an eye, and/or eyes, and/or visual system of a person. The method relies on the reporting of the person of identifications of fixation objects only identifiable when the eye or eyes of the person are accurately fixated on the fixation object. Accordingly active monitoring of a saccade, if a saccade triggering stimulus is employed; or smooth pursuit, if smooth pursuit triggering stimulus is employed, of the eye of the person is not needed for determining whereto to eye or eyes are fixated. The present invention also relates to the use of a system employing the method of the invention. The present invention further relates to a system for the method of the invention and a software product for the system.

Abstract: A method and apparatus for treating visual field loss by disassociating and differentiating between the ambient and focal visual information of a patient. This is achieved by providing a stationary target for the patient to focus on and a moving, spinning or rotating background relative to the stationary target.

Abstract: In a perimeter, luminance judging means measures a sensitivity of an examinee, sensitivity deviation computing means obtains a sensitivity deviation, means for computing ratio to p value obtains a ratio to p value, and means for adding ratios to p value adds ratios to p value of respective measurement positions. The sensitivity deviation at the position where sensitivity dispersion is large is low evaluated and the sensitivity deviation at the position where the sensitivity dispersion is small is highly evaluated. Then, an element of the position where the sensitivity was changed can be also considered in a graph showing test results of perimetry periodically conducted with time.

Abstract: A perimeter of the present invention including: visual field scanning screen generating means; fixation image displaying and controlling means; visual target scan line parallel setting means; visual target displaying and controlling means; statically displaying and controlling means for a specific time; static display position storing means for a specific time; kinetic display and control starting means for giving rise to another of the visual target kinetically based on the start point of a specific time from the position which the static display position storing means stores; detecting means; detection position storing means; distance storing means; and scanning continuation means.

Abstract: An adapter to be applied in contact with an anterior corneal surface. The adapter includes a contact glass portion having a corneal contact surface curvature that is flatter than the undeformed anterior corneal surface. When the contact glass is applied the cornea assumes a deformed state corneal curvature that is parallel to the flatter corneal contact surface curvature. A mount portion circumferentially surrounds the contact glass portion and defines a suction duct that is structured to secure the adapter to the cornea by negative pressure when the suction duct is brought into contact with a surface of the eye surrounding the contact glass portion. The suction duct is partially defined by a peripheral edge of the mount that extends outwardly away from the mount portion and toward but not intersecting or extending beyond a geometric continuation of the corneal contact surface curvature.

Abstract: A perimeter has fixation state judging means for individually judging a fixation state of an examinee in connection with each presented stimulus, and the fixation state judging means individually judges the fixation state whenever the stimulus is presented. Even if defective fixation is judged, retest is conducted on only a point where the stimulus was presented, which was judged to be defective fixation. Then, examiner's burden and examinee's burden can be lightened, the test time can be made shorter and test efficiency can be improved in comparison with a case where the whole test is retried from the first as a conventional way.

Abstract: A virtual sensitivity value which is obtained, variously changing a pupil diameter is measured in advance for many examinees, and volume of correction which is necessary at the time when the sensitivity value is corrected into one in a standard pupil diameter is stored as correction volume database. An apparatus has measurement means for measuring the pupil diameter of the eye to be examined, computing means for computing a shape parameter rate of the measured pupil diameter to the standard pupil diameter, and judgment means for computing volume of correction by referring to the correction volume database from the shape parameter rate and correcting the virtual sensitivity value obtained by measurement of the eye to be examined and for judging a sensitivity step of the eye to be examined.

Abstract: A perimeter performs a kinetic visual field examination on the basis of a response as to whether a subject visually recognizes a displayed stimulus for kinetic visual field examination. The stimulus is displayed a series of times on an inner surface of a visual field dome. An operation is performed in which the subject is made aware of an operating sound of the perimeter while no stimulus is actually displayed. The operation is performed at a predetermined frequency during the display times of the stimulus, and a duration of the operation is determined in accordance with a response time by the subject to the displayed stimulus. The reliability of the kinetic visual field examination is evaluated on the basis of the response of the subject in the performed operation.

Abstract: A device to carry out tests of the macula of a subject's eye to identify disease such as age related macular degeneration. The device includes a stimulus light source comprising a stimulus spheroidal chamber with a stimulus light located therein to emit light through an aperture in the stimulus spheroidal chamber into the eye of a subject. The stimulus light source may include a plurality of light emitting diodes of differing colors. A controller controls the intensity and the color of the light emitted through the aperture of the stimulus spheroidal chamber to the subject. There is also an adapting light source comprising a light contained within an adapting spheroidal chamber. The adapting light source provides a bright light that can be used to remove the subject's dark adaption. There is also an alignment detection system that verifies that the gaze of the subject is toward the stimulus light source.

Abstract: A virtual sensitivity value which is obtained, variously changing a pupil diameter is measured in advance for many examinees, and volume of correction which is necessary at the time when the sensitivity value is corrected into one in a standard pupil diameter is stored as correction volume database. An apparatus has measurement means for measuring the pupil diameter of the eye to be examined, computing means for computing a shape parameter rate of the measured pupil diameter to the standard pupil diameter, and judgment means for computing volume of correction by referring to the correction volume database from the shape parameter rate and correcting the virtual sensitivity value obtained by measurement of the eye to be examined and for judging a sensitivity step of the eye to be examined.

Abstract: Perimeter has input means for inputting identification data of an examinee and a kind of perimetry to be conducted, means for judging whether or not the examinee has already received the perimetry, means to read examinee measurement information, means to judge whether or not a kind of inputted perimetry is different from the past perimetry, means to compute and determine initial stimulus luminance of the perimetry to be conducted from now on as a value equal to the sensitivity which is shown in sensitivity distribution data or closer thereto from the sensitivity distribution data of the past perimetry if different kind is judged, and means for starting the perimetry with the determined initial stimulus luminance.

Abstract: There is provided a perimeter that allows a reliability evaluation to be performed in a kinetic visual field examination. A stimulus for examination is displayed onto an inner surface of a visual field dome and moved at a constant speed on a meridian toward the center of the dome. A subject responds to the stimulus for examination when he visually recognized the moving stimulus. There is displayed a false-negative stimulus, which is more visible than the stimulus for examination, or a false-positive stimulus, which corresponds to the operating sound of the perimeter without any stimulus display. The visual field examination results are evaluated on the basis of a response made by the subject to the false-negative and the false-positive stimuli. This arrangement allows the reliability of the examination results in a kinetic visual field examination to be satisfactorily evaluated.

Abstract: A perimeter for examining a visual field condition of an examinee's eye, includes: a target presenting unit a response unit brain activity detecting unit which detects an activity condition of a visual cortex of the examinee; and an operation unit which determines if the response with the response unit with respect to presentation of the target is resulted from a fact that the examinee can perceive the target based on a detection result of the brain activity detecting unit and which obtains the visual field condition on the basis of the presentation condition of the target and the response result in consideration of the determination result of the brain activity detecting unit.

Abstract: A device for examining the visual field of the human eye which includes a cup-shaped screen, onto the base of which one or several test marks are projected, and usable for both kinetic and also static perimetry testing and offers test marks of a uniform size and brightness over the entire testing area. The screen consists for this purpose of a transparent material, whereby the test marks are projected from the back side onto the screen approximately parallel to the surface normal. The test mark is thereby arranged to move parallel and relative to the back side of the screen, so that each test mark is moved at an equidistant spacing from the screen.

Abstract: A method and apparatus are disclosed for using Virtual Reality for testing and quantifying visual information from the eye, the visual pathways, and the brain. Head-gear configuration allows the patient to observe a field of view into which sequenced test stimuli are presented by an excitation device commanded by a computer. Interactive sensory feedback both to and from the patient enables computer-driven presentation and modulation of test stimuli to measure with precision such parameters as visual field performance, visual acuity, and color vision. Using the system allows the patient unprecedented freedom of movement of the head and body, thus minimizing or even eliminating the stress and fatigue common with conventional non-Virtual Reality visual field testing systems.

Abstract: An embodiment of the present invention is a refractively corrected, wavelength selective, transparent visual field test occluder for a non-tested eye used in a visual field testing apparatus which uses a stimulus that produces light in a first color spectral range and a background illumination that produces light in a second color spectral range, the visual field test occluder comprising: (a) a base; (b) a fastener configured to fasten the base over a subject's eye; (c) a mounting affixed to the base configured to hold a filter and a refractive lens; and (d) a filter held in the mounting; wherein the filter substantially prevents transmission of light in the first color spectral range and substantially transmits light in the second color spectral range.

Abstract: An apparatus for measuring a visual field of a patient, especially characteristics of X ganglion cells, displays a series of targets to a patient. A ramp stimulus is used to measure characteristics of X ganglion cells. A target size setting device sets targets of various sizes. A stimulus intensity changing device changes the intensity of the stimulus in accordance with the size set by the target size setting device. A response device measures the response from the patient, that is, whether the patient senses the target. A memory stores the intensity of stimulus and target size corresponding to the patient's responses.

Abstract: A training device for the therapy of, in particular, brain-damaged patients having perception defects, includes a large number of signalers (6) arranged on one surface (4) for the production of perceptual stimuli, a marking element that is firmly attached in a specific location on the surface (4) and on which the patient must focus his eyes during the therapy, a start-signaling device (16) for producing a starting signal, a control mechanism (20), a reaction-detecting device (22), and a time-determining device (24).

Abstract: A perimeter capable of objectively adding useful testing points without relying on an operator's intuitional judgment, and capable of performing a reliable test of the field of vision without imposing a useless burden on a subject. The perimeter includes a CPU 11 and a display portion 18. The CPU 11 forms data, which include estimated values, on a visual field characteristic distribution by making an interpolation between tested values of a subject's eye which are obtained by exhibiting a plurality of targets. The display portion 18 displays an unreliable distribution WP indicating a domain estimated to be distant from the tested values on the basis of data on the visual field characteristic distribution and data, which include the tested values, on a distribution of an estimated neighborhood of the tested values.

Abstract: In a method of checking the threshold values of a subject's perception of visual stimuli, for each one of a selection of test series, the estimated error of a threshold value estimate of the test series is used to judge whether the test series is to be continued or not. This means that a test series may be discontinued as soon as the threshold value thereof can be determined with acceptable accuracy. Preferably, a posterior probability function is used for estimating the error. An apparatus for carrying out the method includes a control unit operating according to the method.

Abstract: An apparatus and method for automated perimetry. A patient interface is adjustable with respect to a previously positioned patient rather than requiring the patient to position him or herself with regard to the perimeter. Fine adjustment of the patient interface with respect to the patient is possible while a perimeter dome is moved away from the patient and patient interface. Once positioned, the perimeter dome is moveable to a position adjacent the patient. A visual stimulus generating and directing device is preferably contained in a first module attachable to the dome. The visual stimuli are directed to various locations in the dome. An optional feature includes an eye sensing device which continuously monitors the size and position of a patient's pupil and correlates this information to the projected stimuli to verify the patient's fixation during testing. The eye sensor is preferably contained within a second module attachable to the dome.

Abstract: A method of analyzing serial automated visual field data calculates a total field vector of the threshold sensitivity of points in a visual field and compares the total field vector with a calculated normal field vector for a given patient. The vector angle between the total field vector and the normal field vector is calculated to determine the distribution of threshold sensitivities to characterize the localization and the magnitude of field changes. In one embodiment, the sensitivities of each point in the visual field with respect to normal sensitivities for each point is plotted for each of a series of time spaced visual field tests. The single plot uses a line symmetrical about a zero axis whose magnitude reflects the difference from the norm for each point in each exam and forms a graphic depiction of changes in the visual field at each point over a series of visual field tests.

Abstract: A perimeter is disclosed in which the projection surface of the bowl includes a hemispherical section bounded by a cylindrical perimeter to impart to the interior projection surface of the instrument a "bullet shaped" profile. The perimeter of preferred dimension includes a reduced diameter hemisphere occupying the central 45.degree. of solid angle from the fixated patient's eye. The cylindrical perimeter is joined to the hemisphere and is generated about a cylindrical axis commencing at the spherical center of the hemisphere and extending outward normally from the hemisphere to the point of patient eye placement. The diameter of the cylinder matches and forms a projection continuum with the radius of the hemisphere.

Abstract: The present invention discloses an automatic perimeter capable of easily adding or deleting the inspecting points.

Abstract: A field test apparatus is disclosed which is interactive both in the automated positioning of trial lenses (used to correct the patient's focal distance to the tester hemispherical projection screen) as well as providing automatic gaze direction determination through automated video surveillance of the patient's eye. A moveable trial lens holder is provided. This trial lens holder is remotely moveable horizontally and vertically and carries light sources for illuminating the eye preferably in the infrared spectrum at oblique angles preferably towards the center of the eye from the periphery of the trial lens holder. In the gaze direction determination system, a gaze direction determination infrared source--preferably on the surface of the screen near the center of the screen--generates a gaze direction determination reflection on the cornea of the eye--this reflection being near the apex of a normal spherical cornea.

Abstract: A method of diagnosing glaucomatous field defects of particular use in diagnosing the early stages of glaucoma and ocular hypertension is disclosed. The method comprises displaying an image comprising an annulus of a first color on a background of a second color to the patient, the annulus having a gap in it at a variable position. The patient is asked to identify the location of the gap and the tonal contrast between the first color and the second color is varied to determined the color contrast sensitivity threshold of the patient. Also disclosed is an apparatus for performing the method.

Abstract: The present invention relates to a perimetric instrument for measuring a range of a visual field of an eye of a man, and more particularly to a perimetric instrument which includes an abnormal visual field pattern analogical inferring section using a multilayer neural network and can analogically infer an abnormal visual field pattern of a measurement object person. Further, the present invention provides a perimetric instrument which can automatically make a determination of an additional target.

Abstract: A perimeter has a predetermined index to be projected onto a fundus of an eye to be examined and an index projection imaging optical system which can form an intermediate image of the index in front of the eye. An optical system as being at least a part of the index-projection imaging optical system, is movable to displace the position of the index image on the fundus of the eye. The index-projection imaging optical system has an image forming section which moves the intermediate image in the direction of the optical axis.

Abstract: A method for the detection of glaucoma which permits the early detection of glaucoma without expensive equipment or a technician. The device for the method comprises a planar surface having a fixation target thereon for focusing a test eye during testing, a mark positioned in a blind spot area outside of the user's area of peripheral vision and at least one additional mark in the field of vision of the user. To perform the method for the determination of glaucoma, the user of the device focuses the test eye on the fixation target eliminating the mark in the blind spot area from the user's vision and ascertaining the visibility of each additional mark.

Abstract: Method and apparatus for visual testing. In one embodiment, for perimetry testing, the method uses threshold light-stimulus values determined at multiple seed locations in a visual field to calculate expected stimulus threshold values at locations which are nearest-neighbors of the seed locations. The expected values at the nearest-neighbor locations are compared with subject responses at these locations, and the correspondence between the two is used to refine and guide line stimulus level presentations at the nearest-neighbor locations. The test is continued until a selected confidence level of response at nearest-neighbor locations is reached.

Abstract: An improvement is described in regard to a target which is useful in a process for measuring eye movement of a subject. The target includes a support member with a flat or planar bottom surface which can rest upon the top edge of the arcuate member which is used in measuring eye movement. The target can be easily moved along the arcuate member in a smooth and steady manner, with the support member resting on the arcuate member.

Abstract: A first light is moved and illuminated by an x-y plotter mechanism on a rear projection screen under computer control so as to be continuously fixated by an eye of a test subject. The computer also causes one or ones of fixed-position second lights, typically sixteen in number positioned in a regular array, to momentarily illuminate at various times corresponding to various positions of the moving first light. The test subject indicates detection or non-detection of the momentary illuminations to the computer by voicing the numbers "1", "2", "3", etc. From successive illuminations and test subject responses the computer is able to survey the entire visual field of each subject's eye in all directions. The surveyed visual field is plotted on graph paper with the same x-y plotter mechanism that is otherwise and at other times used for moving the first light source.

Abstract: Apparatus and method for visual-field testing. The apparatus includes an ocular device which fits over a subject's eye and which has a cavity-like inner surface dimensioned to encompass the subject's visual field. The ocular device is constructed to provide a background glow against which a fixed light image and a series of transient, different-position light image in the subject's visual field can be perceived. The images are preferably formed by a Badal-optical system which allows the images to be perceived without the need for corrective lenses. Also disclosed is a tandem-optics system for coordinately focusing fixed- and movable-position light image assemblies.

Abstract: A method for diagnosing deficiencies in and expanding the size of a person's "Useful Field Of View" (UFOV). The UFOV is determined by the eccentricity (in degrees of visual angle) at which peripheral targets (presented within an embedding context) can be localized 50% of the time while performing a concurrent visual task in central vision. The method provides multiple blocks of trials, each block of trials consists of displaying a plurality of times before a subject's vision a set of four sequentially presented images having specific characteristics, and the specific characteristics of each block of trials is changed each time a new block of trials is displayed before the subject.

Abstract: A cornea-borne image and light display device (10) comprising a pair of scleral-rider devices (10), (20) similar to contact lenses, which mount on the corneas of the viewer's eyes to present images within the viewer's eyes. The images to the devices is supplied through a respective fiber-optic bundle (14), (16) that derives its light from a light projector (12). Two embodiments are presented, in one, the fiber-optics directly transmit the light source from the projector (12), in the second the optic fibers reflect the light from a plurality of mirrors embedded within the device.

Abstract: A perimeter having an image projection system which projects an undistorted line target across the full range of a patient's field of vision is disclosed. The image projection system includes a projector, a bundle of optical fiber elements, and lenses associated with the optical fiber elements adapted to focus the target onto the observation hemisphere of the perimeter. The perimeter may also be provided with a fixation monitor system which monitors the patient's gaze and which will interrupt projection of the target when fixation is lost. The fixation monitor includes at least one sensor for detecting the intensity of infrared light reflected off the patient's eye, and a comparator adapted to compare the output signals from each sensor during the examination with base signals obtained at fixation. Any signal variation will indicate that fixation has been lost and projection of the target will be interrupted. Projection will resume once fixation has been reestablished.

Abstract: An automatic perimeter comprising stimulus presentation unit for presenting stimuli to examine a patient's eyesight, an examination program memory for memorizing a plurality of examination programs which present stimuli under different presentation conditions, a selector for selecting a first examination program for the first examination, and a presentation controller for controlling said stimulus presentation unit so that stimulus presentation for said first examination is carried out under a presentation program selected by a selecting command if the selecting command is applied to the selector and carried out under a predetermined presentation program if the selecting command is not applied to the selector.

Abstract: In an eye field tester, a vidicon camera observes the eye being tested and relays the resultant low light level image to the periphery of a digital display. The digital display contains both an image of the eye on the periphery and the plot of the visual field of the eye under test in the center. The vidicon observing the position of the eye has its horizontal and vertical sync pulses software generated to presettable counters. These counters generate corresponding delayed horizontal sync and vertical sync pulses for the vidicon. As a result of the delayed sync pulses, the central eye image of the vidicon is offset to the periphery of the digital screen (typically to the upper left-hand portion thereof). The offset image is gated into character spaces on the digital screen utilizing software generated character attribute.

Abstract: A method for controlling the fixation of the eye of a patient during measuring of the sensitivity of the retina of the eye using a perimeter tester having a plurality of spaced testing light points of adjustable brightness, including the steps of adjusting the testing light point which lies in the center to the threshold value of the center of the eye of the patient, and thereafter repeatedly illuminating this testing light point with the threshold value or a super-threshold value near the threshold (1-4 dB superthreshold) to facilitate control of the fixation during the entire examination.

Abstract: An automatic perimeter automatically presenting stimuli in a plurality of conditions, in which the presentation of stimuli can be readily stopped by an operator during the presentation, and an accurate examination of eyesight is carried out in accordance with eliminating the few latest perception signals before the stimulus presentation is stopped during an examination of eyesight.

Abstract: In an eye field tester, a vidicon camera observes the eye being tested and relays the resultant low light level image to the periphery of a digital display. The digital display contains both an image of the eye on the periphery and the plot of the visual field of the eye under test in the center. The vidicon observing the position of the eye has its horizontal and vertical sync pulses software generated to presettable counters. These counters generate corresponding delayed horizontal sync and vertical sync pulses for the vidicon. As a result of the delayed sync pulses, the central eye image of the vidicon is offset to the periphery of the digital screen (typically to the upper left-hand portion thereof). The offset image is gated into character spaces on the digital screen utilizing software generated character attribute.

Abstract: This invention relates to a cupola-type visual stimulation ophthalmological pparatus for examining the visual field of a patient and performing electrophysiological examinations. It comprises a projection screen consisting of the inner surface of a hemispherical cupola, the patient's eye being disposed centrally of the cupola during the examination. A device for projecting visual stimuli on the screen is provided in the upper portion of the cupola and comprises essentially a casing incorporating a light source, filter means, an object mask, a lens and a movable reflecting mirror located in the vicinity of the cupola center. This mirror is adapted to project toward any desired point of the screen a luminous stimulus perceived by the patient for measuring the extent of the patient's visual field. Moreover, with the projection device it is possible to illuminate the complete visual field according to criteria relating specifically to electrophysiological examinations.

Abstract: A field tester wherein a patient's tested eye is located at the center of an interior hemisphere defining a projection surface and wherein a light spot is projected onto said surface from an eccentric location is disclosed. Optics in common with the projector assure that the off-center projected light is of constant intensity and diameter as selected for each test sequence according to test criteria. Specifically, a filament light source is projected to a collimating lens. The light source is re-imaged to a system lens stop. There is a movable aperture between the collimating lens and the first lens of telescopic optics for projecting the image of the aperture onto the projection surface of the sphere. By using a coordinate transform to predict the distance from the point of light source projection to the projection surface of the sphere, the movable aperture is registered to a conjugate distance with respect to the telescope optics.

Abstract: A method and apparatus for providing a uniform testing field for visual field mapping includes a concave viewing screen and a plurality of selectively illuminated test points spaced thereabout. A testing device selects test points randomly and sequentially and records a subject response to map the visual field. Those test points not selected at any given time are strobed with a pulse intensity, duration, and repetition rate to render the test points equal in luminance to the surrounding background areas of the screen.

Abstract: The invention relates to an arrangement for test mark positioning in spheric perimeters particularly for use in ophthalmological examinations. A semi-spherical perimeter screen has a central portion upon which a fixed mark is projected by a double projector the back-projection of which is indicated upon a visual field chart which permits recording of said back-projected fixed mark. A further projector connected to the displaceable visual field chart carrier produces discrete test marks via light cables around the central portion of said screen. Thus it is feasible to continuously detect the visual field of a patient's eye by cooperation between the patient's eye, the fixed mark and the discrete marks and by respective displacements of the projectors and hence the marks involved.

Abstract: A device for measuring the field of vision for a person wearing a mask indes a mask support to which the mask can be clamped and which is horizontally movable for aligning one of the subject's eyes with a horizontal axis. A scale support carries a scale member that is rotatably mounted around the horizontal axis and which carries a slidable indicator which can be slid to angles from 0.degree. to 90.degree. with respect to the axis. A mirror is attached to the scale support and lies on the axis for aiding and aligning on the subject's eye with the axis. A pointer is connected to a far end of the scale member and is used to locate the vertical perpendicular position of the subject's eye on the horizontal axis. The scale member is rotatably mounted on the scale support about the horizontal axis and the scale support is movable vertically to bring the horizontal axis into alignment with the subject's eye.