Optics: eye examining – vision testing and correcting – Eye examining or testing instrument – Objective type
Reexamination Certificate
2000-08-25
2001-10-02
Manuel, George (Department: 3737)
Optics: eye examining, vision testing and correcting
Eye examining or testing instrument
Objective type
Reexamination Certificate
active
06296358
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the field of ocular imaging, and, more particularly, to devices for imaging the ocular fundus.
2. Description of Related Art
The term ocular fundus refers to the inside back surface of the eye containing the retina, blood vessels, nerve fibers, and other structures. The appearance of the fundus is affected by a wide variety of pathologies, both ocular and systemic, such as glaucoma, macular degeneration, diabetes, and many others. For these reasons, most routine physical examinations and virtually all ophthalmic examinations include careful examination of the ocular fundus.
Routine examination of the ocular fundus (hereinafter referred to as fundus) is performed using an ophthalmoscope, which is a small, hand-held device that shines light through the patient's pupil to illuminate the fundus. The light reflected from the patient's fundus enters the examiner's eye, properly focused, so that the examiner can see the fundus structures.
If a hard copy of the fundus view is desired, a device called a fundus camera can be used. However, to use existing fundus cameras successfully is a very difficult undertaking. The operator must (1) position the fundus camera at the correct distance from the eye, (2) position it precisely in the vertical and horizontal directions in such a way that the light properly enters the pupil of the patient's eye, (3) refine the horizontal and vertical adjustments so that the light reflected from the front surface of the eye, the cornea, does not enter the camera, (4) position a visual target for the patient to look at so that the desired region of the fundus will be imaged, and (5) focus the fundus image. Al these operations must be performed on an eye that is often moving. Therefore, the use of existing fundus cameras requires a significant amount of training and skill; even the most skilled operators often collect a large number of images of a single eye in order to select one that is of good quality.
In existing fundus cameras, alignment and focusing are performed under visual control by the operator. This usually requires that the patient's eye be brightly illuminated. Such illumination would normally cause the pupils to constrict to a size too small to obtain good images. Therefore, most existing fundus cameras require that the patient's pupil be dilated by drugs.
U.S. Pat. No. 4,715,703 describes an invention made by one of the present inventors and discloses apparatus for analyzing the ocular fundus. The disclosure in this patent is incorporated herein by reference.
SUMMARY OF THE INVENTION
The present invention is in the nature of a fundus camera which automatically and quickly performs all the aligning and focusing functions. As a result, any unskilled person can learn to obtain high quality images after only a few minutes of training and the entire imaging procedure requires far less time than existing fundus cameras. Moreover, all of the automatic aligning and focusing procedures are performed using barely visible infrared illumination. With such illumination, the patient's pupils do not constrict and for all but patients with unusually small natural pupils, no artificial dilation is required. The fundus images can be obtained under infrared illumination and are acceptable for many purposes so that the patient need not be subjected to the extremely bright flashes required for existing fundus cameras. To obtain standard color images using the present invention, it is sometimes necessary to illuminate the eye with flashes of visible light. However, such images can be obtained in a time appreciably shorter than the reaction time of the pupil, so that the pupil constriction that results from the visible flash does not interfere with image collection. Unlike existing fundus cameras, the present invention provides for automatic selection of arbitrary wavelengths of the illuminating light. This facility has two significant advantages. First, it is possible to select illuminating wavelengths that enhance the visibility of certain fundus features. For example, certain near-infrared wavelengths render the early stages of macular degeneration more visible than under white illumination. Second, by careful selection of two or more wavelengths in the near infrared, it is possible to obtain a set of images which, when properly processed, generate a full color fundus image that appears very similar to a color image obtained with white light. Thus, it is possible to obtain acceptable color fundus images without subjecting the patient to bright flashes.
It is therefore a primary object of the present invention to provide a fundus imager which automatically positions fundus illuminating radiation to enter the pupil while preventing reflection from the cornea from obscuring the fundus image, irrespective of movement of the eye or the patient's head within the head restraint.
Another object of the present invention is to provide automatic focusing of the fundus image based upon the image itself.
Yet another object of the present invention is to provide automatic positioning of one or a sequence of fixation targets to select the sections(s) of the fundus to be imaged.
Still another object of the present invention is to provide a fundus imager for collecting a set of images that can be arranged in a montage to provide a very wide angle fundus image facilitated by the capability of the fundus imager to automatically align and focus the images.
A further object of the present invention is to provide automatic setting of video levels in a fundus imager to use the full range of levels available.
Yet another object of the present invention is to permit aligning and focusing a fundus imager under infrared illumination to permit imaging without drug induced dilation of the pupil.
A yet further object of the present invention is to provide for automatic selection of illumination wavelength.
A yet further object of the present invention is to provide a colored image from a fundus imager by sequential imaging and registration of images.
A yet further object of the present invention is to provide an apparently normally colored image generated by two infrared wavelengths.
A yet further object of the present invention is to provide for automatic acquisition by a fundus imager of a stereo image pair having a known stereo base.
A yet further object of the present invention is to provide a head positioning spectacle frame for use with a fundus imager.
A yet further object of the present invention is to accommodate for astigmatism and/or extreme near and far sightedness by placing a lens of the patient's glasses in the path of illumination of the fundus imager.
A yet further object of the present invention is to provide a method for automatically positioning the illuminating radiation of a fundus imager to prevent corneal reflections from obscuring the fundus image obtained.
A yet further object of the present invention is to provide a method for automatic focusing in a fundus imager.
These and other objects of the present invention will become apparent to those skilled in the art as the description thereof proceeds.
REFERENCES:
patent: 3915564 (1975-10-01), Urban
patent: 4187014 (1980-02-01), Kato et al.
patent: 4283124 (1981-08-01), Matsumura
patent: 4405215 (1983-09-01), Sano et al.
patent: 4436388 (1984-03-01), Takahashi et al.
patent: 4469416 (1984-09-01), Isono
patent: 4579430 (1986-04-01), Bille
patent: 4715703 (1987-12-01), Cornsweet et al.
patent: 5090799 (1992-02-01), Makino et al.
patent: 5129400 (1992-07-01), Makino et al.
patent: 5233517 (1993-08-01), Jindra
patent: 5371557 (1994-12-01), Nanjho et al.
patent: 5382988 (1995-01-01), Nanjo
patent: 5508760 (1996-04-01), Kobayashi et al.
patent: 5572266 (1996-11-01), Ohtsuka
patent: 5764341 (1998-06-01), Fujieda et al.
patent: 5844658 (1998-12-01), Kishida et al.
patent: 5912720 (1999-06-01), Berger et al.
patent: 5914771 (1999-06-01), Biber
patent: 6086205 (2000-07-01), Svetliza
Abstract of U.S
Buck Gary F.
Cornsweet Tom N.
Cahill Sutton & Thomas P.L.C.
Manuel George
Visual Pathways, Inc.
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