Petitioner: Haag-Streit AG
`Petitioner: Haag-Streit AG
`
`Ex. 100(cid:27)
`
`EX. 1008
`
`

`

`|||I||lllllllllllllllllllllllllllllllllllllllllIllllllllllllllllllIllllllll
`U5005225859A
`5,225,859
`[11] Patent Number:
`Umted States Patent
`Fleischman
`[45] Date of Patent:
`Jul. 6, 1993
`
`
`[19]
`
`[54.] APPARATUS AND METHOD FOR CAPTURE
`AND PROCESSING OF OCULAR AND
`RETINAL IMAGES
`
`[75]
`
`Inventor:
`
`‘
`Jay A. Fleischman, Greenwrch,
`Conn.
`
`,
`_
`.
`.
`[73] Assrgnee: Eemozom Scientific, Inc., Tucson,
`112.
`[21] App]. No.: 775,689
`.
`[22] F‘led:
`0°" 10’ 1991
`[51]
`Int. Cl.5 ................................................ A6lB 3/14
`[52] US. Cl. .................................... 351/206; 351/221;
`351/246
`[58] Field of Search ................ 351/206, 205, 221, 246
`
`[56]
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`4,854,691
`8/1989 Sekine et a1.
`........................ 351/221
`.
`Primary Examiner—Rodney B. Bovemlck
`Assistant Examiner—Hung Xuan Dang
`Attorney, Agent, or Firm—Rosenbaum & Schwartz
`57
`ABSTRACT
`[
`1
`.
`.
`A combmed apparatus for the capture, processmg and
`archival recording of digital or analog images of the
`ocular and retinal anatomy by indirect ophthalmoscopy
`and fluorescence angiography.
`
`14 Claims, 2 Drawing Sheets
`
`VIDEO
`MONITOR
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`

`

`US. Patent
`
`July 6, 1993
`
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`US. Patent
`
`July 6, 1993
`
`Sheet 2 of 2
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`5,225,859
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`

`1
`
`5,225,859
`
`APPARATUS AND METHOD FOR CAPTURE AND
`PROCESSING OF OCULAR AND RETINAL
`IMAGES
`
`BACKGROUND OF THE INVENTION
`
`10
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`15
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`20
`
`25
`
`The present invention relates generally to fundus and
`ocular cameras and indirect ophthalmoscopes used by
`ophthalmologists or ophthalmic photographers to cap-
`ture and record images of the ocular and retinal anat-
`omy used in diagnosis of ocular and retinal abnormali-
`ties. More particularly, the present invention relates to a
`combined apparatus for the capture, processing and
`archival recording of digital or analog images of the
`ocular and retinal anatomy.
`Generally there are three methods used to photo-
`graphically document the retinal fundus with an eye
`fundus camera. The first method is to take a picture of
`the eye fundus using visible light, the second method is
`to take a picture of the eye fundus vasculature using a
`fluorescent dye, known as fluorescein angiography and
`the third method is to take a picture of the eye choroidal
`vasculature using and infrared light stimulated dye,
`known as indocyanine green angiography.
`Fluorescein angiography is a widely used method in
`which a fluorescent dye, typically sodium fluorescein
`(C20H1205Na), and more recently indocyanine green, is
`administered intravascularly to the patient and the eye
`fundus is exposed to light energy to excite the fluores- 30
`cein in the eye fundus vasculature. Excitation of the
`fluorescein causes a fluorescence which is visible to the
`practitioner when using certain optical filters and may
`be recorded by photography.
`Fluorescence is luminescence which is maintained 35
`only by exposure to a continuous excitatory energy.
`Fluorescence is emission of light immediately after exci-
`tation and cessation of emission immediately after cessa-
`tion of excitatory radiation. Luminescence refers gener-
`ally to the emission of light due to any cause other than 40
`high temperature. The second law of thermodynamics
`dictates that emitted energy must be less than the en-
`ergy absorbed. Thus, since energy and wavelength are
`reciprocally related, luminescence, and, hence, fluores-
`cence, always entails a shift from a shorter wavelength, 45
`i.e., higher energy, in the excitation radiation to a longer
`wavelength, i.e., lower energy, in the emitted light.
`Sodium fluorescein, for example, in solution at proper
`concentration and pH,
`is excited by light energy be-
`tween 465 to 490 nm in the blue portion of the light 50
`spectrum, and fluoresces at a peak wavelength of 520 to
`530 nm in the green-yellow portion of the light spec-
`trum. As with all known fluorescent materials, sodium
`fluorescein has an energy absorption curve which de-
`creases in the shorter wavelength and rapidly in the 55
`longer wavelengths, and a fluorescence which rises
`rapidly over the shorter wavelengths and diminishes
`slowly over the longer wavelengths. Sodium fluores-
`cein is known to fluoresce over a spectral curve range
`of 485 to 600 nm.
`Fluorescein angiography is typically conducted by
`intravenously injecting sodium fluorescein into an arm
`vein of the subject to be tested. The normal fluorescein
`angiogram can be divided generally into the following
`phases:
`i. early choroidal filling and choroidal flush;
`ii. retinal artery filling and increased choroidal filling;
`iii. arterio-venous filling and laminar flow;
`
`60
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`65
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`2
`iv. full arterio-venous filling;
`v. retinal venous phase; and
`vi.
`late arterio-venous recirculation phase with de-
`creased retinal and choroidal fluorescence.
`It usually takes about 5 to 10 seconds before the fluo-
`rescein enters the eye fundus vasculature. The early
`signs of fluorescence is referred to as the “choroidal
`flush” due to entry of the fluorescein into the choroid.
`This choroidal fluorescence is seen because unbound
`fluorescein molecules pass through the fenestra of the
`choriocapillaris and fill
`the extracellular choroidal
`space. One to two seconds after the choroidal flush is
`noted, fluorescence appears in the central retinal artery
`and the larger precapillary arteriole branches. The fluo-
`rescein then passes into the retinal capillaries, the post
`capillary venules and the major retinal veins and the
`central retinal vein. The early phase of the retinal ve-
`nous fluorescein pattern is often referred to as laminar
`flow. This laminar flow provides a characteristic pic-
`ture because the vascular flow is faster in the center of
`the larger retinal veins than on the sides. The fluores-
`cence along the walls of the veins becomes thicker, and
`eventually there is a complete fluorescence within the
`lumen of the vein. Fluorescence of the disc originates
`from the posterior ciliary vascular system and from the
`capillaries of the central retinal artery on the surface of
`the disc. The macular region of the normal fluorescein
`angiogram characteristically has a darker appearance
`than the surrounding region. Xanthophyll in the sen-
`sory retina partially blocks blue light
`transmission
`needed to excite the fluorescein in the choroid. Addi-
`
`tionally, the increased density of the melanin pigment
`granules in the retinal pigment epithelium underlying
`the macula also block some of the choroidal fluores-
`cence during fluorescein fundus angiography. In the
`case of indocyanine green fundus angiography, both the
`infrared excitation wavelength and infrared fluores-
`cence wavelength easily pass through the xanthophyll
`and melanine pigment layers to reveal details of the
`choriodal vasculature layer.
`During fluorescein angiography, a flash of white light
`from a retinal fundus camera passes through a blue
`excitation optical filter which passes blue light having a
`peak wavelength of 465 to 490 nm and strikes the fluo-
`rescein molecules in the ocular vasculature. The blue
`light excites the fluorescein molecules which fluoresce
`and emit a yellow green light with a peak wavelength of
`520 to 530 nm. Both yellow-green light as well as re-
`flected blue light emerges from the patient’s eye. A
`yellow-green optical barrier filter is used to block the ,
`blue light and transmit only the yellow-green wave-
`lengths onto camera film and to the viewing oculars.
`As noted above, angiography of the eye fundus typi-
`cally employs sodium fluorescein dye as the imaging
`medium. Information concerning the dynamics of reti-
`nal and choroidal,circulation have been derived princi-
`pally from fluorescein angiography. Except for the
`earliest choroidal arterial
`filling,
`i.e.,
`the choroidal
`flush, visualization of the choroidal circulation is lim-
`ited by both the spectral characteristics of the eye pig-
`ments and tissue and the rapid extravasation of fluores-
`cein from the choriocapillaris.
`As noted by Hochheimer, et al., US. Pat. No.
`3,893,447, choroidal circulation may be visualized sepa-
`rately from the retinal circulation by using indocyanine
`green dye. The methods and principles concerning in-
`docyanine green fundus angiography are essentially
`identical to fluorescein fundus angiography. The princi-
`
`

`

`3
`pal difference with fluorescein fundus angiography is
`that indocyanine green fluoresces in the infrared spec-
`trum and allows visualization of the choroidal circula-
`tion dynamics on infrared film or by and infrared detec-
`tor. As taught by Hochheimer, sodium fluorescein may
`be mixed with indocyanine green and the mixture in-
`jected intravenously. Angiograms of the separate circu-
`lation are simultaneously produced by two cameras
`mounted on a fundus camera equipped with an optical
`separation device. The light energy returning from the
`ocular fundus during each flash firing is split by the
`optical separator into two or more discrete beams. One
`split beam corresponds to the spectral range of the so-
`dium fluorescein fluorescence, i.e., 490—520 nm, in the
`retinal circulation, while the second split beam corre-
`sponds to the absorption spectrum of indocyanine
`green, which is near 800 nm, in the choroidal circula-
`tion. In the infrared spectrum at about 800 nm, macular
`xanthophyll and the pigment epithelium are relatively
`transparent and energy absorption by indocyanine
`green is detectable. The two cameras are equipped with
`appropriate optical filters to pass only the yellow-green
`light of the sodium fluorescein or the infrared light of
`the indocyanine green dye.
`,
`Fluorescein angiography typically employs two opti-
`cal filters; an exciter filter and a barrier filter. The ex-
`citer filter transmits blue light at 465 nm to 490 nm, the
`absorption peak of fluorescein excitation. The barrier
`filter transmits light at 525 to 530 nm, the fluorescent
`peak of fluorescein. Optimally, there should be little or
`no overlap between the filter curves to eliminate
`pseudofluorescence. Pseudofluorescence is non-fluores-
`cent light which passes through both the exciter and
`barrier filters. Pseudofluorescent
`light records onto
`black and white film and results in reduced contrast and
`artefactual
`fluorescence. Conventional optical ' filters
`are available as matched sets from Baird-Atomic, Spec-
`trotech and De Lori.
`
`Imaging of the peripheral retina using standard fun-
`dus cameras is a difficult task which requires a high
`degree of skill and practice. Problems with patient posi-
`tion. alignment and focusing are compounded by mar-
`ginal corneal astigmatism, unsteady patients, light re-
`flexes and awkward camera displacement. While vari-
`ous cameras employ different compensating mecha-
`nisms, peripheral imaging remains a significant short-
`coming of conventional fundus cameras.
`Finally, current fundus cameras employ a variety of
`films to record the fluorescent light emanating from the
`retina. The film most frequently used in Kodak “TRI-
`X" film which is a fairly fast film of ASA 400. Angiog-
`raphers also employ a variety of different film develop-
`ment techniques which enhance detail but compromise
`contrast. The developed negatives or prints made from
`the resulting negatives are often enclosed in patient
`record files. Videocameras may be employed in place of
`the film camera as illustrated by European Patent Ap-
`plication No. 153,570 published Jan. 16, 1985.
`Indirect ophthalmoscopy is a method which permits
`visualization of the peripheral retinal area. Examples of
`indirect ophthalmoscopes and methods of ophthalmos-
`copy are provided by U.S. Pat. No. 4,146,310 to
`Kohayakawa, Y., et al., U.S. Pat. No. 4,018,514 to
`Plummer, and U.S. Pat. No. 3,881,812 to Ben-Tovim.
`Each of these systems employ a lamp, a mirror worn on
`a harness placed on the observer’s head, and a lens
`which the observer must hold in front of the eye to be
`examined. Use of indirect ophthalmoscopes requires
`
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`5,225,859
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`4
`positioning of the light relative to the both the observ-
`er’s and subject’s eye, positioning the mirror at a proper
`angle and placing the lens at a defined distance from the
`subject’s eye and tilted to exclude reflexes. The retina is
`observed through the lens held in front of the patient’s
`eye. A film or video camera is sometimes used in con-
`juction with the indirect ophthalmoscope to photo-
`graphically record the retinal image.
`_
`Current fundus cameras cost tens of thousands of
`
`dollars and add-on video cameras or image processing
`equipment only adds to the total system cost. Moreover,
`processing and manipulating the current film or video
`images requires cumbersome and expensive digitization
`as a separate process which further increases cost and
`introduces a time delay into the diagnostic process.
`With the advent of floppy disc based video and still
`cameras, direct analog and digital processing of the
`retinal images obtained by either a fundus camera or an
`indirect ophthalmoscope is possible. Moreover, the use
`of optical barrier filters requires careful'matching to the
`exciter filter to minimize pseudofluorescence. There is,
`however, usually some remaining spectral overlap
`which tends to degrade image quality. Electronic imag-
`ing processing permits the elimination of the barrier
`filter by electronically filtering all wavelengths except
`that desired for imaging and recording purposes.
`SUMMARY OF THE INVENTION
`
`An indirect ophthalmoscopy/fundus camera is pro-
`vided which incorporates full visible spectrum, partial
`spectrum, or infrared sensitive still or video cameras, an
`analog or digital recorder, a beam splitter to pass 800
`nm wavelength signals to the infrared videocamera, in
`the case where indocyanine green dye fluorescence is to
`be recorded, electronic filters which process light emit-
`ting from the retina and passes only 520 nm wavelength
`yellow-green signals, and control processors for the
`purpose of color and fluorescent fundus imaging, in-
`cluding, for example fluorescein and indocyanine green
`fluorescent fundus imaging. The invention incorporates
`an automatic synchronization between an intravenous
`dye injector and the recorder operating sequences.
`BRIEF DESCRIPTION OF THE FIGURES
`
`FIG. 1 is a diagrammatic representation of the retinal
`imaging system of the present invention.
`FIG. 2 is a graph of the spectral curves of exciter and
`barrier optical
`filters,
`illustrating the pseudofluores-
`cence region.
`FIG. 3 is a graph illustrating the optimum spectral
`curves of exciter and barrier filters.
`
`FIG. 4 is a diagrammatic illustration generally repre-
`sentative of the process of fluorescein angiography.
`DETAILED DESCRIPTION OF THE
`
`PREFERRED EMBODIMENTS
`Turning now to the accompanying Figures, and with
`particular reference to FIG. 1, there is shown the imag-
`ing system 10in accordance with the present invention.
`Imaging system 10 consists generally of an foot pedal
`12, an injector 13, an indirect ophthalmoscope or fundus
`camera 16, a camera process controller 18, and analog
`or digital recorder/player 20 and, optionally, a video
`monitor 22, printer 24 or archival recorder 26. The foot
`pedal 12 is activated by the practitioner to initiate the
`imaging process. Foot pedal 12 causes the injector 14,
`preferably an automatic injector, such as are known in
`the art, to initiate injection of a bolus of a fluorescent
`
`

`

`5,225,859
`
`5
`dye, such as sodium fluorescein or indocyanine green,
`into an intravenous line placed in the patient’s arm. For
`purposes of illustration only, reference is made to the
`use of sodium fluorescein, and its spectral characteris-
`tics. Those skilled in the art will understand, however,
`that other fluorescent dyes suitable for human use are
`contemplated and may be used.
`The indirect ophthalmoscope or fundus camera 16 is
`used to visualize the fluorescent retinal image in a con-
`ventional manner as well as imaged onto a video camera
`or cameras. The camera controller 18 receives the elec-
`tronic video image of the fundus or ocular area and,
`when set for fluorescein or indocyanine green angiogra-
`phy,
`interposes electronic filters onto the energy to
`filter all but 520 nm wavelengths in the case of fluores-
`cein or about 800 nm wavelengths in the case of indocy-
`anine green. The electronic filter may consist of any
`opto-electronic coupling, such as a photo-sensor, which
`converts optical energy into electrical energy. The
`converted electric signals will correspond to the wave-
`length range of the optical signal. The correlation be-
`tween wavelength and electronic frequency establishes
`the selection of appropriate electronic filter to filter out
`all but the frequency corresponding to the 520 nm light
`energy wavelength. Camera controller 18 may, for
`example, be a charge coupled device (CCD) camera of
`the type which receives optical energy and converts it
`to electronic signals for digital recording. The use of
`CCD cameras in digital image processing systems for
`analysis of coronary arteriograms and ventriculograms
`has been shown by Lowinger, T., et al., Computers in .
`Cardiology, IEEE Computer Society, Los Alamitos,
`Calif. 1989, pp. 433—455, which is incorporated by refer-
`ence. Additionally, the use of CCD sensors for image
`processing in analysis of electrophoresis gels, digital
`microscope imaging or in computer-assisted quantita-
`tive analysis of angiographic images recorded on 35 mm
`film is illustrated by Muser, M. H., et al., Proceedings of
`SPIE— The International Society for Optical Engineering,
`V. 1448, p. 106—112 (1991), which is also hereby incor-
`porated by reference.
`Altemative camera types which electronically record
`images in analog form may also be employed. An exam-
`ple of such analog recording is a video-tape recording
`of an eye fundus image taken from signal outputs to a
`monitor television as described by Sekine, A., et al., in
`US. Pat. No. 4,854,691. Sekine, hereby incorporated by
`reference, discloses a laser-based eye fundus camera
`system in which a photomultipliers are input with light
`reflected from the eye fundus and a photoelectric ele-
`ment is input with a part of a laser beam. The photomul-
`tipliers provide a signal, which is amplified and input to
`an analog/digital converter. The resulting digital sig-
`nals are input to memory registers, which record the
`image frames, after the digital signals are output to a
`digital/analog converter to generate a video signal, for
`display on a monitor television. This type of analog/-
`digital to digital/analog conversion is not needed where
`CCD cameras are employed, but may be used in the
`present invention to provide analog signal processing.
`Cameras which record and store images on micro.
`floppy diskettes are known in the art and are available
`from Canon, Matushita or Sony. These types of cameras
`are capable of recording twenty-five high resolution or
`fifty lower resolution images in NTSC, high-definition
`format analog video images. Analog/digital recorder/-
`player 20 is preferably one of these types of analog
`camera recorders which receive the image from the
`
`6
`indirect ophthalmoscope or fundus camera and record
`the image, in analog or digital form, on a microfloppy
`diskette, for later playback and record keeping. The
`camera 16 may be optically coupled to the indirect
`ophthalmoscope or fundus camera in any manner as is
`well known in the art.
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`The camera processor controller 18 may be used to
`modify images previously stored on the microfloppy
`diskette, or the images may be modified by a computer
`equipped with software for video frame grabbing and
`graphic manipulation.
`Additionally, a video monitor 22 may be provided for
`viewing the image either directly from the camera con-
`troller 18 or as played from the analog digital recorder
`20. A printer 24 may be provided to provide hard copy
`output of the stored images.- Finally, an archival re-
`corder 26, such as a compact disc based optical recorder
`such as CD~WORM may be used for archival record
`storage.
`When used for color retinal photography, the camera
`controller 18 placed in its color setting 17 whereby all
`light spectra are transmitted to the camera recorder 20.
`However, when used for fluorescein or indocyanine
`green angiography, the cameral controller is placed in
`its angiography setting 15 appropriate for the type of
`angiography being performed. The angiography setting
`15 interposes the appropriate electronic filters on the
`signal transmitted from the camera controller 18, and
`passes only that signal corresponding to the fluores-
`cence wavelength of the fluorescent dye employed.
`FIG. 4 is a diagrammatic representation of the pro-
`cess of fluorescein angiography. Light energy 60, such
`as that provided by a flash unit (not shown), is passed
`through the exciter filter 62. Exciter filter 62 is selected
`to pass a peak light wavelength corresponding to the
`excitatory energy required for the selected fluorescent
`dye, i.e., sodium fluorescein ~465 nm to 490 nm, the
`absorption peak of fluorescein excitation or for indocya-
`nine green ~800 nm. The filtered light energy 64 is
`introduced into the eye and onto the eye fundus 66. The
`fundus vasculature is already perfused with the i.v.
`fluorescent dye 70. The fluorescent dye absorbs the
`excitatory light energy 64 and fluoresces at about 525 to
`530 nm. The fluorescent energy, combined with re-
`flected blue light form a returned light energy 72. A
`barrier filter 74 filters the returned light energy 72 to
`pass only the fluorescent energy at about 525 to 530 nm,
`and filter the reflected blue light at 465—490 nm. The
`filtered fluorescent energy 76 is passed through the
`barrier filter for viewing and/or recording.
`FIG. 2 is a graph depicting typical spectral curves for
`optical exciter 30 and barrier 32 filters. As noted above,
`the exciter filter 30 is typified by a slower absorption
`rate and a rapid decrease in light transmission. The
`barrier filter 32 is typified by a relatively faster absorp-
`tion rate and a slower decrease in light transmission.
`FIG. 3, however, is illustrative of optimum or desired
`light transmission characteristics for exciter filters 40 or
`barrier filters 42. As illustrated in FIG. 3, the exciter
`filter 40 is preferably characterized by an immediate
`increase from 0% light
`transmission to 100% light
`transmission at the desired activation wavelength 41, or
`over a very narrow wavelength bandwidth, a plateau
`transmission 43 at the upper limit of filter transmission
`and an immediate decrease to 0% transmission once the
`upper or extinction wavelength 45 is reached. The bar-
`rier filter spectral curve 42 has similar characteristics,
`with a specific or narrow bandwidth activation’wave-
`
`

`

`7
`length 47 and a plateau 49. The barrier filter may be
`selected to have an immediate cessation of transmission
`50 at an extinction wavelength 51 or may be configured
`for light transmission to a desired wavelength 52.
`When set to the color mode 17, the system 10 of the
`present invention operates by activating a light source
`or flash unit on the indirect ophthalmoscope 16 to gen-
`erate and image which is captured on the analog/digital
`recorder/player 20 for recording on a microfloppy
`diskette. The recorder/player 20 may be incorporated
`with or directly coupled to the indirect ophthalmo-
`scope 16 to receive the retinal image. The retinal image
`stored on the microfloppy diskette may then be re-
`trieved for playback and viewing on the television or
`video monitor 22, print out onto the printer 24 or archi-
`val storage on the archival recorder 26.
`When set to the angiography mode 15, the system 10
`of the invention operates in a like manner, except that an
`exciter filter is interposed in the flash unit or light
`source to provide the excitatory wavelength for the
`fluorescent dye employed. The exciter filter may be
`manually placed in the light path, or may be driven with
`a solenoid which permits strobing of the filtered excit-
`atory light. Preferably the strobing should provide an
`excitatory flash at a rate of about one per second. The
`camera processor/controller 18 will receive both the
`reflected excitatory light and the fluorescence from the
`retina, and impose an electronic barrier filter, in a man-
`ner described above, to filter the reflected excitatory
`light and pass only the fluorescent spectrum. In the case
`of sodium fluorescein peak fluorescence occurs at 520
`nm, hence, the electronic filter will pass electronic sig-
`nals corresponding only to the 520 nm wavelength. In
`the case of indocyanine green peak fluorescence occurs
`at about 800 nm, hence, the electronic filter will pass
`electronic signals corresponding only to the 800 nm
`wavelength. The signals passed through the barrier
`filter will be stored on the microfloppy associated with
`the analog/digital recorder/player 20, for subsequent
`retrieval, playing, printing or archival storage as previ-
`ously noted.
`-
`Thus, the present invention has been described with
`reference to its preferred embodiment. Those skilled in
`the art will understand, however, that changes in fluo-
`rescent dye selection, component parts, or processing
`parameters may be made within the scope of the present
`invention. The description of the preferred embodiment
`of the invention should not be construed as limiting the
`spirit and scope of the invention. For example, future
`developments in fluorescent dyes, fluorescent color
`spectra, and analog or digital color or monochrome
`processing may enhance the functionality of the present
`invention, without departing from the spirit and scope
`of the invention.
`I claim:
`
`1. An apparatus for visualizing, imaging and captur-
`ing ocular and retinal images, comprising:
`means for generating non-coherent light energy;
`portable means for directing generated light energy
`into an eye to be tested;
`filtering means for transmitting a desired wavelength
`of the generated light energy to the eye to be tested
`and passing a different desired wavelength of light
`energy emitted form the eye to be tested;
`signal processing means for receiving light energy
`emitted from the eye to be tested and converting
`the received light energy into at least one of an
`analog or digital electronic signal;
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`recording means for receiving at least one of an ana-
`log or digital electronic signal, recording the re-
`ceived electronic signal onto an archival recording
`medium thereby obtaining a substantially complete
`recorded image of the eye fundus and generating
`an output signal; and
`viewing means for receiving the output signal re-
`ceived from the recording means and viewing the
`retinal image.
`2. The apparatus according to claim 1, further com-
`prising:
`means for injecting a fluorescent dye into the ocular
`or retinal vasculature and synchronizing the re-
`cording means;
`.
`a fluorescent dye having known absorption and fluo-
`rescence wavelengths;
`an exciter filter which receives the generated light
`energy and passes only light energy corresponding
`to the absorption wavelength of the fluorescent
`dye; and '
`a barrier filter which receives at least one of the light
`energies corresponding to the absorption wave-
`length of the fluorescent dye reflected from the eye
`to be tested and the fluorescence wavelength of the
`fluorescent dye, and passes only the fluorescence
`wavelength of the fluorescent dye.
`-
`3. The apparatus according to claim 1 wherein said
`filtering means further comprises an electronic circuit
`which transmits generated light energy having a wave-
`length substantially corresponding only to an absorp-
`tion wavelength of a fluorescent dye injected into the
`eye to be tested, and passes only received light energy
`substantially corresponding to a fluorescent wave-
`length, of the fluorescent dye, emitted from the eye to
`be tested.
`
`4. The apparatus according to claim 1, wherein said
`recording means further comprises an electronic cam-
`era which records optical light energy as at least one of
`analog or digital signals on a recording medium.
`5. The apparatus according to claim 4, wherein said
`electronic camera further comprises an electronic cam-
`era electronically coupled to a recorder/reader for
`electromagnetically recording analog signals onto a
`magnetic medium.
`6. The apparatus according to claim 1, wherein said
`viewing means further comprises at
`least one of an
`analog or digital video display.
`7. An optical apparatus for combined indirect oph-
`thalmoscopy and angiography of the eye fundus, com-
`prising:
`a light generator for generating non-coherent light of
`a wavelength capable of generating fluorescence
`radiation from a fluorescent material circulating in
`blood vessels of an eye fundus of a person to be
`tested;
`,
`a portable light director for aiming light into the
`fundus of the eye of a person to be tested;
`a light receiver for receiving light emitted from the
`eye fundus of a person to be tested;
`a photo-electric converter for converting light signals
`received by the light receiver to electrical signals;
`an electronic circuit switchable to pass all electrical
`signals, for indirect ophthalmoscopy, and to filter
`the electrical signals such that only electrical sig-
`nals corresponding to the optical wavelength of the
`fluorescence pass through the electronic circuit,
`for angiography; and
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`a recorder/player for recording the filtered elec-
`tronic signals onto an archival recording medium
`and providing an output signal for viewing the
`recorded signals on a video display.
`8. The optical apparatus according to claim 7,
`wherein said recorder/player further comprises an elec-
`tronic camera which records optical light energy as at
`least one of analog or digital signals on a recording
`medium.
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`spectra of electronic signals corresponding to a
`identified wavelengths of received light;
`recording said processed electronic signals onto a
`recording medium; and
`viewing said processing electronic signals either di-
`rectly or from said recording medium on a video
`display capable of generating an optical
`image
`from the electronic signals.
`12. The method of claim 11, wherein said step of
`exposing the eye to be tested to a portable, non-coher-
`ent light source further comprises the step of generating
`fluorescence radiation from a fluorescent material cir-
`culating in a blood vessel of an eye fundus of a person to
`be tested.
`13. The method of claim 12, wherein said step of
`processing the electronic signals further comprises the
`step of selecting electronic signals corresponding to a
`peak optical wavelength of the fluorescence radiation,
`and filtering non-selected electronic signals, thereby
`allowing said selected electronic signals to pass to said
`recorder.
`
`14. The method claim 11, wherein said step of receiv-
`ing light emitted from the eye to be tested further com—
`prises the step of providing an electronic camera which
`records optical light energy as at least one of analog or
`digital signals on a recording medium.
`*
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`9. The optical apparatus according to claim 8,
`wherein said electronic camera further comprises an
`electronic camera electronically coupled to a recor-
`der/reader for electromagnetically recording analog
`signals onto a magnetic medium.
`10. The apparatus according to claim 7, wherein the
`video display further comprises at least one of an analog
`or digital video display.
`11. A method of visualizing ocular and retinal anato-
`mies, comprising the steps of:
`exposing an eye to be tested to a portable, non-coher-
`ent light source;
`receiving light emitted from the eye to be tested;
`converting said received light to electronic signals;
`processing said electronic signals by selecting one of 25
`a full spectrum of electronic signals corresponding
`to the full spectrum of received light or identified
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