Optics: eye examining – vision testing and correcting – Eye examining or testing instrument – Objective type
Reexamination Certificate
2000-09-08
2001-12-04
Manuel, George (Department: 3737)
Optics: eye examining, vision testing and correcting
Eye examining or testing instrument
Objective type
Reexamination Certificate
active
06325513
ABSTRACT:
BACKGROUND OF THE INVENTION
a) Field of the Invention
The invention relates to an arrangement for examination of vision functions, and, in particular, an arrangement for the subjective determination of refraction in the eye.
b) Description of the Related Art
There are various known spectacle type or helmet type frames which arrange screens in front of the eye of the observer or which reflect the image generated by screens or displays in front of the eye of the observer: U.S. Pat. Nos. 5,076,275, 4,361,384, 5,162,828, U.S. 4,869,575, Enhanced Vision. “V-max”, brochure 800-440-9476, 1996. “Virtual displays” of this kind are sold by Virtual Research Systems, Inc. (FAG), for example.
U.S. Pat. No. 5,369,415 and EP 562,742 describe “direct retinal scan displays” in which only very low outputs (not more than 20 micro watts) are required owing to direct “writing” of the image information on the fundus oculi of the observer. Video information (e.g., RGB signals) is modulated on one or more laser beams and the latter is/are deflected in the x-direction and y-direction via scanners (e.g., piezo-crystals) and reflected into the observer's eye via a plane surface which can be spectacle glass. Variable optics serve to focus the beams on the retina.
U.S. Pat. No. 5,467,104 and WO 94/09472 describe a “virtual retina display” with high resolution and color representation. Light from lasers or LEDs is modulated, transmitted via light guides, and projected directly onto the retina by means of microscanners and projection optics. The reflecting element can also be a splitter mirror, so that the projected image is superimposed on the surroundings.
In WO 96/17562, a scanning unit is provided on a spectacle type frame and projects an image onto the retina via the reflecting spectacle lenses or glasses.
A “pupil tracking system” monitors the position of the eyes and displaces the projection direction so as always to strike the pupil of the observer. In DE 4091126, the patient views a screen through spectacles with liquid crystal shutters, on which screen are displayed symbols for binocular vision testing.
DE 4326760 C2 describes a device for testing central vision functions, preferably for perimetric examinations, wherein a light-proof or light-tight spectacle type carrier contains image-generating display screens for generating test marks or optotypes and an optical imaging system for compensation of refractive anomalies. The natural visual impression is impaired by the part of the spectacles arranged in front of the eyes which has screens in the viewing direction.
Examination instruments such as phoropters in which, e.g., spherical or cylindrical test glasses are swiveled in front of the eye to determine defective eyesight based on information from the test subject are known for determining subjective refraction and for determining other functions of the human eye. A disadvantage herein is that the test subject does not assume a relaxed posture and the natural visual impression is corrupted.
Therefore, arrangements have been developed to enable so-called “free-vision” refractive testing (U.S. Pat. No. 3,927,933, DE 2647848 A1, DD 293045 B5, DD 282851 B5, DD 273771 A1).
Further, test equipment for determining other functions of the human eye are known (OCULU.S.-Binoptometer, Binotest) to acquire information on the visual performance (e.g., color vision, stereo vision, driving vision) of the patient's eyes based on information given by the patient. These arrangements also have the disadvantage that they take up a relatively large amount of space and are poorly suited for mobile use, e.g., in developing countries. When used for testing defective vision of persons, especially for the first time, the test subject will often exhibit objective shyness of the medical equipment, which makes the examination difficult or even impossible.
OBJECT AND SUMMARY OF THE INVENTION
The primary object of the invention is therefore to improve and facilitate examination of defective vision and other visual functions.
In accordance with the invention, an arrangement for determining subjective refraction and/or for determining other visual functions, comprises at least one light source, at least one light modulator which follows the light source, a driving unit for controlling the modulator for modulating video information, two dimensional deflecting means for the light for generating an image, optical transmission means for transmitting the light of the light source and optical projection means for projecting the image onto the retina of the eye to be examined.
The invention can be used for testing the most important vision functions and for refractive determination in humans.
The very compact construction and wearing of light spectacles eliminates the need to look into a device. There is no more swiveling of large examination units (phoropters) in front of the eye. It is possible to superpose generated images on the surroundings in combination with a comfortable, relaxed sitting posture. The very high resolution which is made possible is coupled with low power consumption. There can be separate displays for the right eye and left eye, which is important for all binocular tests, wherein the disadvantages of other image-separating methods which partially determine function (color separation, polar separation, shutter principle, mechanical separators) can be eliminated.
In particular, the following functions can be tested according to the invention:
I.
Visual acuity (far, near, monocular, binocular), e.g., by means of the reflector (spectacle glass) with two zones:
a) the far part (image from infinity—e.g., plane mirror) and
b) the near part (image from defined distance, e.g., 40 cm—e.g., concave mirror). All other test symbols can be generated; thus, a large selection is possible. Binocular testing is effected by a unit for each eye using the known adjustment possibilities of test spectacles and of eye tracking.
II.
Driving-related Eye Test
In this case, special testing processes are possible in accordance with the specifics of different nations.
III.
Stereopsis Examination
Display of test images (different lateral disparity possible) which are offset laterally relative to one another by displacement of the scanned images. The lateral displacement path is calibrated in angle minutes stereopsis.
IV.
Phoria (angular vision deficiency)
Display of two separate images of different content. A displacement of these images on the retina of the test subject is made possible by displacement at the scanner or screen, wherein the displacement path can be calibrated in angular vision deficiency (prism diopters).
V.
Color Vision Test
When three light sources (RGB or RGY) are used, different color tests are possible (e.g., color charts; two fields analogous to the anomaloscope).
VI.
Visual Field Test
This test can be conducted in a manner analogous to the perimeter (full vision field or screening—central field, e.g., 30°). The point of fixation is made in the center by a (blinking) dot. The vision field test is carried out by dot display corresponding to preselectable program sequences.
VII.
Sensitivity to Glare, Dark Adaptation
The blinding or dazzling of the eye is simulated by means of laterally disposed light sources; at the same time tests are performed which, in addition, can also be varied in contrast.
VIII.
Contrast-dependent Visual Acuity
Tests can be carried out with different gray steps by modulating the intensity of the beams. The contrast ratios of the performed tests can accordingly be changed and a dependency of the detected visual acuity step upon contrast can be determined.
IX.
Objective Refraction
Evaluation of the (preferably infrared) light reflected by the retina in a generally known autorefractor system. In cooperation with a retinal scan display, an alternative to the conventional phoropter/acuity projector/autorefractometer.
X.
Subjective Refraction
A sharp imaging of the displayed images on the retina can be achieved through the intermediary of variable spherical and cylindrical optics. The adjustment
Bergner Roland
Voigt Klaus-Ditmar
Carl Zeiss Jena GmbH
Manuel George
Reed Smith LLP
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