WO2000021432A9 - Methods and apparatus for digital ocular imaging - Google Patents
Methods and apparatus for digital ocular imagingInfo
- Publication number
- WO2000021432A9 WO2000021432A9 PCT/US1999/023872 US9923872W WO0021432A9 WO 2000021432 A9 WO2000021432 A9 WO 2000021432A9 US 9923872 W US9923872 W US 9923872W WO 0021432 A9 WO0021432 A9 WO 0021432A9
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- eye
- path
- imaging
- fundus camera
- illuminating
- Prior art date
Links
Classifications
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
- A61B3/10—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions
- A61B3/14—Arrangements specially adapted for eye photography
- A61B3/15—Arrangements specially adapted for eye photography with means for aligning, spacing or blocking spurious reflection ; with means for relaxing
- A61B3/156—Arrangements specially adapted for eye photography with means for aligning, spacing or blocking spurious reflection ; with means for relaxing for blocking
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
- A61B3/10—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions
- A61B3/12—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions for looking at the eye fundus, e.g. ophthalmoscopes
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F9/00—Methods or devices for treatment of the eyes; Devices for putting-in contact lenses; Devices to correct squinting; Apparatus to guide the blind; Protective devices for the eyes, carried on the body or in the hand
- A61F9/007—Methods or devices for eye surgery
- A61F9/008—Methods or devices for eye surgery using laser
Definitions
- the invention relates generally to the field of digital ocular imaging for ophthalmological examinations and procedures, and more specifically to improved methods and apparatus for imaging the retina and other internal surfaces of the eye
- Fundus cameras and other ocular imaging devices have been used by ophthalmologists and optometrists to diagnose and record eye conditions
- Major manufacturers of fundus cameras include Canon, Kowa, Nikon, Topcon, and Zeiss
- a conventional fundus camera projects light through a dilated pupil and records images of the ocular surface on film
- a camera such as a conventional 35 mm camera or a digital camera is often used to record still images of the fundus
- Conventional fundus cameras require complex light projection and viewing systems with multiple lenses, filters, mirrors and other optics which greatly increase the cost and complexity of the camera
- Conventional fundus cameras typically utilize powerful light sources to provide sufficient illumination of the ocular surfaces because the multiple lenses and other optics cause significant amounts of light reflection and scatte ⁇ ng
- the high intensity light source and the large power supply which are constructed from expensive materials, further increase the cost of known fundus cameras
- the OIS product includes software that automatically overlays selected images, based on user identification of landmarks to be aligned between the two images
- the present invention provides an ocular fundus camera which digitally records one or a series of images of the inner portion of the eye
- the present invention does not use conventional recording media such as cameras which require film.
- the invention utilizes digital video images which can be instantaneously and continuously displayed and stored
- the invention provides for live, instantaneous imaging of the fundus
- the invention allows for single images to be selected from the video and these single images may be selected, for example, for further quantitative processing
- the digital images from the fundus camera of the invention can be displayed on a monitor or television system, and the images can be stored by a computer system or other data storage device.
- the computer system may also be used, for example, to compare stored images, map specific image features, filter particular elements, process the images for increased definition, highlight specific portions of an image, etc
- the present invention can be used with angiography which involves the injection of a dye such as fluorescein into the blood to visualize blood vessels in the eye
- Conventional angiography involves injecting dye into the arm of the subject and taking one or more pictures with a conventional fundus camera when the dye reaches the vessels in the eye.
- the present invention in contrast, provides for injecting dye into the arm while the operator views the blood vessels of the fundus on the monitor
- the operator can see the dye as it enters and flows through the blood vessels of the fundus Therefore, the operator can view and analyze the circulation of the blood in the eye, and the operator can simultaneously select and/or store one or more digital images of the eye.
- the live motion video imaging of the present invention provides the unique ability to capture and study specific and ongoing retinal dynamics, which is particularly important for procedures such as angiography Additionally, the live viewing by the operator of the inner portions of the eye makes the fundus camera of the present invention simpler and easier to use because the operator can focus and align the camera in real time
- the present invention also allows a sequence of digital images to be obtained and this permits better analysis and diagnosis by a health care provider than conventional fundus cameras with still pictures
- the digital video images may be used to watch blood flow through the small, complex vascular system of the eye
- the video images can be used to observe the expansion and contraction of the blood vessels as the heart beats, and the camera can provide information such as the size and location of various blood vessels or other retinal features
- the present invention may be particularly advantageous for clinical evaluation of vascular circulation.
- the digital images of the present invention may be used to identify specific structures such as pathologies in the eye. These pathologies may include, for example, retinal detachments or tears, macular degeneration, etc.
- the fundus camera of the present invention may also be used to view and/or track specific elements such as the optical nerve for diabetic retinopathy screening, glaucoma detection and other diagnostics Because the precise locations of these pathologies may be determined by the fundus camera at any given time, medical instruments such as lasers may be used to treat the pathologies with minimal damage or irritation to the surrounding tissue
- a fundus camera including a light source for illuminating a portion of the eye and an illumination path for directing light from the light source to the eye
- the fundus camera also includes an imaging path for viewing at least a portion of the eye and a receiving member which converts the light from the imaging path into electrical signals corresponding to digital images
- the light source includes a halogen lamp and the illumination path includes a filter, collimating lens, mirror, mask and objective lens
- the imaging path desirably includes an objective lens and a mask and, more desirably, the objective lens and the mask of the illumination path and the imaging path are common
- the objective lens is preferably aspherical and the illumination and imaging paths are preferably transmitted through only a portion of the objective lens
- the receiving member is preferably a CCD camera which continuously converts the light from the imaging path into electrical signals corresponding to digital images
- a fundus camera including a light source for illuminating the eye, an illumination path for directing light from the light source to the eye, an imaging path for viewing at least a portion of the eye and a receiving member
- the imaging path includes a relay lens, a mask and an objective lens
- the objective lens images a portion of the eye onto an image plane and the relay lens images the image plane onto the receiving member
- the mask is preferably located proximate the imaging plane
- Yet another aspect of the present invention is a fundus camera including a light source for illuminating at least a portion an eye, an illuminating path including an objective lens for directing light from the light source to the eye and an imaging path including the objective lens for viewing at least a portion of the eye
- the objective lens is configured to focus the illuminating and imaging paths onto the pupil of the eye
- a portion of the illuminating path is generally aligned with an illumination axis and the imaging axis is generally aligned with an imaging axis and, more desirably, the imaging axis is offset from the illuminating axis
- Still another aspect of the present invention is a fundus camera including a light source for illuminating at least a portion of the eye to be viewed
- the fundus camera also includes a collimating lens for directing light from the light source to a mirror, the mirror reflecting the light through an aperture in a mask to an objective lens and the light propagating through the objective lens and illuminating at least a portion of the eye
- the fundus camera also includes an imaging path for viewing a desired portion of the eye and a receiving member for receiving light from the imaging path
- the receiving member converts the light from the imaging path into electrical signals corresponding to digital images which can be simultaneously viewed by an observer and recorded
- the receiving member is preferably a CCD camera and the images are preferably stored as part of a computer system
- Yet another aspect of the present invention is a fundus camera which has a single illumination path and a single imaging path These two paths allow the eye to be illuminated and the camera is configured so that an observer can simultaneously view an interior portion of the eye and take images of the interior portion of the eye
- the camera uses the same light source at generally the same intensity for both observation and taking images of the fundus
- the fundus camera does not require any movable parts or components to select between different optical paths or to allow images of the interior portion of the eye to be taken
- Still another aspect of the present invention is a fundus camera with an illuminating path and an imaging path
- the illuminating path is focused proximate the pupil of the eye and the illuminating path forms an illuminating area.
- the imaging path is focused proximate the pupil of the eye and the imaging path forms an imaging area
- the illuminating area formed the illuminating path and the imaging area formed by the imaging path substantially overlap.
- the illuminating area and the imaging area on the pupil are substantially distinct
- Yet another aspect of the present invention is a fundus camera including an illuminating path including a mask and an objective lens, and an imaging path including the mask, the objective lens, and a relay lens and a receiving member
- the mask is positioned in the imaging path between the objective lens and the relay lens, and the objective lens images a portion of the eye onto an imaging plane and the relay lens images the imaging plane onto a receiving member
- the fundus camera of the present invention advantageously includes an improved optical system with simplified illumination and imaging paths
- the optical system of the present invention is much easier to use, operate and manufacture, and it is less costly than conventional systems because it has fewer optical components
- less light is lost by reflections and scattering and this allows a less powerful light source to be used
- the less powerful light source allows a smaller power supply to be used
- the fundus camera of the present invention provides better images of the inner ocular surfaces of the eye Specifically, the fundus camera has a larger depth of field than conventional fundus cameras and this results in clearer images of the retina Further, the present invention may use white light or infrared light and the optical system virtually eliminates undesired reflections These and other features of the present invention allow the fundus camera to obtain improved images of the eye
- Figure 1 is a schematic view of an optical system of a conventional fundus camera
- Figure 2 is a schematic view of an optical system of another conventional fundus camera
- Figure 3 is a schematic diagram of a preferred embodiment of the inventive integrated imaging system and fundus camera
- Figure 4 is a schematic diagram of an optical layout of an ophthalmological imaging camera according to a first embodiment of the invention
- Figure 5 is a schematic diagram of an optical layout of an ophthalmological imaging camera according to a second embodiment of the invention
- Figure 6 is an optical diagram showing convergence of the light beam and image at the pupil in the system of the present invention.
- Figure 7 is a schematic diagram of a lamp control circuit useful in the present invention.
- Figure 8 is a schematic view of an optical system of the ocular fundus camera in accordance with a preferred embodiment of the present invention.
- Figure 8 A is an enlarged cross section of an eye, illustrating the illumination path and imaging path
- Figure 9 is a cross sectional view along lines 4-4 of a portion of the ocular fundus camera shown in Figure 8, illustrating the mask
- Figure 10 is a block diagram of an ocular fundus camera in connection with another preferred embodiment of the present invention
- Figure 11 A is an enlarged schematic view of a portion of the eye, illustrating distinct illumination and imaging areas on the pupil
- Figure 1 IB is an enlarged schematic view of a portion of the eye, illustrating substantially overlapping illumination and imaging areas on the pupil
- Figure 12 is an enlarged schematic view of a portion of the eye, illustrating the overlapping illumination area and the viewing area on the fundus
- the conventional fundus camera 10 has many different optical components with multiple light paths
- the conventional fundus camera 10 includes an observation light path 11 with an observation light source 12, condensing lens 14, dichroic mirror 16, plate 18 with a ring-shaped slit 19, relay lens 20 and perforated mirror 22
- the dichroic mirror 16 is configured to transmit visible light and reflect infrared light Light emitted by the observation light source 12 is transmitted through the condensing lens 14 to the dichroic mirror 16, which reflects only the infrared light This reflected infrared illumination light is directed through the ring-shaped slit 19 of the plate 18, relay lens 20, and to the perforated mirror 22
- the infrared illumination light is reflected by the perforated mirror 22 to the objective lens 24 and the eye E which is to be tested or observed
- the infrared light forms an image in the vicinity of a cornea C of the eye E and the fundus F is illuminated with the infrared illumination light passing through the cornea
- the fundus camera 50 includes an observation light path 51 with an observation light source 52
- the observation light path 51 also includes a condenser lens 54, photographing light source 56, condenser lens 58, mirror 60, ring slit 62 with an annular aperture (not shown in the accompanying figure), relay lens 64, mirror 66 having an aperture 67 at its center, and an objective lens 68
- light from the observation light source 52 travels along the observation light path 51 to the eye E and the light allows the eye to be observed
- the known fundus camera 50 shown in Figure 2 also includes a photographic optical path 70 with a focusing lens 72, photographing lens 74 and movable mirror 76 which are sequentially arranged behind the mirror 66 with the aperture 67
- the movable mirror 76 is pivotable and in a first position it reflects the light along an observation path 80 which includes a field lens 82, mirror 84 and an eyepiece lens 86 This allows an observer E' to view the fundus F when looking through the eye piece 86
- the movable mirror 76 can also be pivoted upwardly as indicated by arrow 77 to a second position which allows the light to create an image on the film 78
- the observer E' can look through the eye piece 86 and along the observation optical path 80 and the photographic optical path 70 to the fundus F
- a solenoid 88 moves a reflecting member 90 with a concave mirror into the observation light path 51 between the condenser lens 54 and the photographing light source 56 (the reflecting member in the observation light path is shown in phantom), and the photographing light source 56 emits high intensity light which travels along the observation light path 51 to the fundus F of the eye E
- the movable mirror 76 pivots upwardly as shown by arrow 77 to allow the light to strike the film 78 and to prevent light from traveling along the observation optical path 80 to the eye E' of the observer
- the high intensity light illuminates the fundus F and the reflected light travels along the photographic optical path 70 to the film 78 where an image is formed After the picture is taken, the photographic
- Figure 3 shows a block schematic diagram of an optical system 100
- a video camera 122 of an imaging camera subsystem 101 is connected to a capture board 103 in computer 105 so that images from camera subsystem 101 are received and processed by computer 105
- Computer 105 is preferably a personal computer based on an open standard architecture, having an Intel (TM) processor and running Microsoft Windows (TM) or Windows NT (TM) operating systems
- Computer 105 incorporates input and output devices such as a keyboard, mouse, and video display
- Imaging camera subsystem 101 may be mounted on a chinrest and joystick assembly 1 11, which is a device for relatively positioning the imaging camera subsystem 101 and the patient's eye
- the subsystem may be handheld and may be manually positioned relative to the eye for use as a direct ophthalmoscope
- Figure 4 is a schematic diagram of a first embodiment of the optical imaging camera 101
- Camera 101 comprises halogen bulb 102, relay lens group 104, aperture 106, field lens 108, green bandpass filter 1 10, infrared bandpass filter 112, infrared blocking filter 1 13, illumination aperture 1 14, video lens 1 16, spacer 118, video camera 122 incorporating CCD 120, mirror 1 19, objective aperture 124, and objective lens 126
- Camera 101 illuminates the eye 128 using halogen bulb 102 and images internal features of the eye onto CCD 120
- video camera 122 transmits an image signal to capture board 103 (shown in Figure 5) for processing by computer 105 (also shown in Figure 5)
- Video camera 122 may be a device for relatively positioning
- Halogen bulb 102 may be a Welch- Ailyn #EXP 0427-1 20 watt bulb, arranged with its filament perpendicular to the optic projection plane
- the halogen bulb is preferred for its versatility and low cost
- a coherent or multiple wavelength, or Xenon flash light source could also be used if desired
- Bulb 102 is regulated by the lamp control powered by a 12V DC source 109
- the brightness control 107 varies the intensity of the bulb from 2 5 W to 20W under control of the brightness potentiometer Lamp control 107 is also provided with a timer which turns off bulb 102 after a predetermined time, such as nine minutes
- the brightness knob of lamp control 107 may be located on the housing of the device behind the video camera 122
- Power supply 109 is mounted separately and connected to brightness control 107 via a long cable
- Figure 7 is a schematic diagram of a lamp control circuit useful in the present invention
- aperture 106 may be a 1 5 x 3 0 mm aperture, again arranged perpendicularly to the optical projection plane
- Light is then collimated by field lens 108, which is a piano convex lens, for example with a focal length of 63 mm
- field lens 108 which is a piano convex lens, for example with a focal length of 63 mm
- the collimated light generated after the field lens 108 can be varied in intensity, which is inversely proportional to the cross sectional area of the beam, by adjusting the relative distance of the field lens 108 to the aperture 106
- the cross sectional area determines the illuminated area of the retina 128 The larger the area the wider the illuminated field
- the desired mix of intensity and illuminated area is set according to the application, color, red free, FA, or ICG
- Green filter 1 10 may be provided as a bandpass filter with 40 nm bandwidth centered at a 540 nm wavelength
- Infrared bandpass filter 1 12 may have a 60 nm bandpass width centered at a 750 nm wavelength
- IR blocking shortpass filter 1 13 blocks the region above 700 nm
- Infrared bandpass filter 1 12 and IR blocking shortpass filter 1 12 are preferably arranged together on a rotatable mechanism so that these two filters can be readily interchanged by the operator with a single motion
- the device can be used as a non-midriatic fundus camera, in which the infrared bandpass filter is used to set up the picture without constricting the pupil, and the infrared filter is then flipped out of the way and an image captured before the pupil constricts Additional filters may be provided to achieve particular results as desired
- Movement of the filters in and out of the light beam path is preferably manual, although an automated electromechanical system could also be provided if desired
- the light beam passes through illumination aperture 1 14, and is reflected off mirror 119 to pass through the aperture 124
- the beam is then projected by objective lens 126 to a filament equivalent point at the pupil of the eye, which illuminates the retina to an approximately 40 degrees horizontal and 25 degrees vertical segment
- the retina is imaged back by the same objective lens 126 to the objective aperture plane and then focused onto the CCD element 120 by the video lens 116
- the projection and viewing paths are aligned by the illumination aperture 1 14, mirror 119, and objective aperture 124 such that the illuminated and viewed parts of the retina overlap
- the objective aperture 124 is a rectangular mask centered with the optical axis of the CCD element 120 This axis is elevated with respect to the optical axis of the objective lens 126
- the upper and lower edges of the mask are adjusted so that all reflections from the objective lens 126 into the CCD 120 viewing area are eliminated
- the mirror 1 19 is adjusted so that maximum illumination passes through the mask 124 resulting in maximum retinal illumination as well as maximum overlap with the viewing area
- the illumination aperture 1 14 is also a rectangular mask where the edges are adjusted to eliminate reflections from the top edge of the mirror 1 19, and from the edges of the mask of the objective aperture 124
- a back aperture 118B is placed at the nodal point to eliminate further reflections
- a final image mask 120B is placed at the CCD plane
- Objective lens 126 is preferably a double aspheric lens 40 mm in diameter with an interchangeable focal length of 28mm (wide view) and is interchangeable with a 40 mm diameter 38 mm focal length lens for a more magnified view Objective lens 126 is
- the light beam output by the system is very small at the pupil plane
- Light output measurements for the prototype taken with a Graseby Optics radiometer/photometer model 350, showed that the illuminated area at the pupil plane was approximately 2 square mm, with a maximum intensity at the pupil plane of 0 68 mW over the 1 075 square mm aperture of the detector
- Total power projected at the pupil plane was 1 27 mW, while the retinal projected radiance was 0 003 W/(cmsq sr)
- a conventional Topcon TM 50X fundus camera when measured with the same equipment, produced a 50 square mm illuminated area at the pupil plane
- the Topcon camera had an 8 5 mW maximum intensity at the pupil plane with total power to the pupil plane of 425 mW Retinal projected radiance for the Topcon camera was 0 97 W/(cmsq sr)
- the present invention provides a much smaller illumination footprint at the pupil plane with a much lower
- the arrangement and alignment of the objective aperture 124 and the objective lens 126 are significant in that corneal and other reflections are substantially eliminated
- Objective aperture 124 is arranged to pass light through one side of objective lens 126, thus acting as an optical mask
- the offset of the optical axis of the viewing, illumination, and that of the objective lens 126 is equivalent to an apparent (slight) tilt of the objective lens
- This arrangement tends to limit the field of view of the CCD 120 such that a corneal reflection produced by the optical elements falls outside the field of view, and thus does not interfere with viewing the image
- Computer 105 may be provided with software that records individual frames in response to an operator trigger control and performs desired visual and analytical manipulation of the image information
- video sequences observed by the camera may also be recorded
- an entire fundus or slit lamp examination may be recorded by the capture software in an AVI or other standard format
- the software preferably has an automatic registration feature which allows comparing two images collected by the device
- the software may also incorporate a flicker chronoscopy feature in which two images collected at different times, after translation and rotation (but typically not warping) as appropriate for registration purposes, are alternately displayed in the same place on a video screen at a predetermined alternation rate Any differences in the two images as they alternate will create a flickering or flashing effect which draws the eye of the viewer, while in places where there is no significant difference the alternation of the two images will not be perceptible
- the software may perform shape and sector analysis variations of the optic nerve head to determine the likelihood and progression of glaucoma
- Topographical analysis of the optic nerve head may be used to diagnose glaucoma at an early stage in the manner disclosed in U S Patent 5,220,360, which is incorporated herein by reference
- the software may further apply global and sector (local) parameters derived from retinal images to predict glaucoma with clinical accuracy
- This software feature is provided in an analysis module which can be added to the other software.
- glaucoma may be detected using two dimensional gray scale and color retinal images using three types of composite variables Specifically, the system measures (1) average distance between horizontal and vertical rim width, (2) average rim intensity, normalized by average background (outside) intensity, and (3) image "vessel sharpness" index, estimating the presence, bending, and bunching of dark vessels in selected sectors, and uses these three composite variables as predictors of glaucoma Values for these variables which are indicative of glaucoma are determined empirically by analyzing images of eyes known to have glaucoma
- An eye coupler may be mounted on the housing of the ophthalmic camera of the present invention to create an improved direct digital ophthalmoscope
- the foam rubber of the eye coupler has a particular range of density so that some in- and-out motion against the eye is possible for focusing, yet there is resistance to motion against the eye
- the pressure of the foam against the face also has the effect of holding the eye open during an examination
- the foam portion is preferably disposable, and readily removable from the eye coupler for hygienic purposes
- the ocular fundus camera embodiment 200 includes a light projection component 202 for illuminating the fundus of the eye to be tested
- the light projection component 202 includes a light source 204 which is preferably a halogen lamp, but other lights, lamps or energy sources may be used
- a light source 204 which is preferably a halogen lamp, but other lights, lamps or energy sources may be used
- the light source 204 provides visible, white light but light of any color and/or infrared light, for example, may also be provided by the light projection component 202
- the light beam 206 from the light source 204 is directed by an illumination path
- the illumination path 208 includes a first section 209 with one or more filters 210 (Figure 8 illustrates only one filter for simplicity) which are used to provide light with desired characteristics, but the camera 200 may also be used without any filters
- the filter 210 may allow only infrared light to pass, eliminate impurities, polarize the light, allow light of only specific wavelengths to pass, orient the light in a specific direction, etc
- the filter 210 is preferably a spectrally selective filter with a generally circular outer diameter of about 1 0 inches
- the illumination path 208 also includes a collimating lens 212 which collimates the light beam 206, but the light does not have to be collimated
- the collimating lens 212 is circular with an outside diameter of about 1 5 inches
- the light projection component 202, filter 210 and collimating lens 212 are generally aligned parallel to an axis Y which, as shown in the accompanying figure, extends generally vertically
- the light beam 206 passing through the collimating lens 212 travels generally parallel to the axis Y towards a mirror 214
- the accompanying figures illustrate the axis Y as being generally vertically aligned, it will be understood that in use the axis can be at any desired orientation or angle
- the illuminating path 206 can also include other component lens such as focusing, relay or condenser lenses
- the mirror 214 is positioned at an angle a relative to the axis Y so that the mirror 214 reflects at least a portion of the light 206 from the light source 204 through an opening 216 in a mask 218 along a second section 219 of the illumination light path 208
- the mirror 214 is positioned at an angle a of about 235E relative to the axis Y and the mirror 214 reflects the light 220 at an angle a of about 45E relative to the axis X, which is orthogonal to the axis Y
- the mirror 214 is generally rectangular with dimensions of about 1 8 inches by about 1 3, and the mirror 214 is located in a fixed position relative to the X and Y axes, but the mirror can be adjustable to reflect light 220 at other angles a For example, if the mask 218 is moved, the mirror 214 may be adjusted so that the reflected light 220 is properly aligned with the opening 216 in the mask
- the mask 218 is preferably circular with an outer diameter of about 1
- the reflected light 220 passing through the opening 216 along the viewing path travels through the objective lens 226 which is preferably generally circular with an outside diameter of about 1 8 inches More preferably, although not shown in the accompanying figures, the lens 226 is a double aspheric lens which may be obtained from Volx Optical, Inc of Mentor, Ohio The double aspheric lens advantageously provides the same illuminating path for all colors of light
- the double aspheric lens 226 allows white light to be used to illuminate the fundus and this permits the fundus to be imaged in color, but any light with suitable characteristics may be used For example, infrared light may be used so that the pupil does not constrict, but the fundus image is then not in color
- the reflected light 220 only passes through the upper portion of the objective lens 226 and the objective lens converges the light 232 directed towards the eye
- the light 232 propagates through the cornea, anterior chamber, pupil and lens of the eye to illuminate the fundus
- the light 232 illuminates the portion of the eye containing the optic nerve, but any desired portions of the retina may be illuminated
- a light source 204 with a halogen lamp rated at about 24 watts is sufficient to illuminate the eye for purposes of the preferred embodiment of the fundus camera 200, but the lamp may be more or less powerful depending upon the intended use of the camera
- the light 232 passes through the cornea and it is focused proximate the pupil, but the light can also be focused on either side of the pupil It will be appreciated that if the light 232 is focused at the pupil, it will allow the maximum amount of light into the eye because the pupil will not block any of the illumination light Alternatively, if the light is not focused on the pupil, the pupil may block some of the illumination light As discussed below in connection with Figures 6 A and 6B, the light 232 forms an illumination area 235 on the pupil.
- the fundus camera 200 also includes an imaging or viewing path 240 in which the fundus of the eye is imaged
- the imaging path 240 includes a receiving member 242 and relay lens 244
- the receiving member 242 is preferably a CCD camera that receives imaging light from the imaging path 240 and it converts the light images into digital images
- the CCD camera 242 has a sensor which receives the light images and a real-time display that allows an observer to view the fundus while the images are being recorded
- the relay lens 244 is preferably a CCD relay lens which images the viewing light onto the sensor of the CCD camera, but the lens can be any suitable lens
- the CCD relay lens 244 is spaced proximate to and slightly upwardly relative to the mirror 214 and it is configured to receive the imaging light 246 As seen in Figure 8, only the upper portion of the lens 244 receives the imaging light 246, but
- the mask 218 also prevents reflected or scattered imaging light 246 from obscuring or blurring the quality of the image received by the CCD camera 242 As known in the art, light reflections are caused, for example, each time the light passes through a different medium Thus, reflections are caused by the imaging light 246 propagating through the front and rear surfaces of the objective lens 226 and the cornea of the eye The mask 218 blocks these light reflections from reaching the relay lens 244 and this improves the imaging by the camera 200 of the eye Additionally, the mask 218 is specifically positioned between the objective lens
- the objective lens 226 images the fundus onto an image plane A- A and the mask 218 is located at or near the image plane
- the relay lens 244 images the plane A-A onto the CCD camera 242
- the CCD camera 242 and the relay lens 244 are positioned so that the image of the eye through the objective lens 226 is imaged upon the CCD camera 242
- the imaging light 246 passes through the cornea and it is focused at or near the pupil Because the light 246 is focused to a small area proximate the pupil, the eye does not have to be dilated to allow adequate viewing of the fundus Preferably, however, the eye is dilated to allow more light 246 to pass through the pupil and this allows images to be more easily taken, as well as a larger part of the fundus to be imaged
- the fundus camera 200 is connected to a monitor or display 250 which allows images of the fundus to be instantaneously displayed and a storage device 252 which allows the images to be digitally stored or recorded
- the output from the CCD camera member 242 is provided to the monitor 250 and the storage device 252, and this output is preferably provided simultaneously
- the images may be displayed or stored in any desired format, such as color, black and white, etc and all or only a portion of the images may be displayed or stored
- the storage device 252 is part of a computer system with sufficient memory to store the images and sufficient processing abilities to process the images
- the computer system may be configured, for example, to compare the images with other images or manipulate the images, for example, by mapping, filtering or definition processing of the images
- the computer system may include other items such as displays, monitors, internal and external memory devices, etc
- the optical system of the fundus camera 200 described above is an improvement over conventional fundus cameras because it has a larger depth of field
- the objective lens 226 focuses the illuminating light path 208 on or near the pupil of the eye
- the objective lens focuses the imaging light path 240 on or near the pupil of the eye
- These small focus points positioned at or near the pupil allow the eye to be examined with or without dilation of the eye
- the portion of the illuminating light path 208 which traverses the pupil creates an illuminating area 235
- the portion of the imaging light path 240 which traverses the pupil creates an imaging area 247
- the illuminating area 235 and imaging area 247 on the pupil are positioned without any overlapping as shown in Figure 11 A
- the separate illuminating and imaging areas 235 and 247 decrease the reflections in the imaging path 240, which improves the quality of the image
- the illumination and imaging areas 235 and 247 are preferably each less than one-half the area of the pupil so that
- the fundus camera 200 is preferably mounted inside a support structure such as a case 260
- the case 260 provides mounting surfaces for the various optical components and it allows the operator to readily move the camera 200
- the camera 200 is movable about the eye so that images of different portions of the fundus can be obtained While the fundus camera 200 may be hand-held, the camera is preferably attached to a stand (not shown in the accompanying figures) which allows the camera to be moved about the eye More preferably, the stand allows the camera to move upwardly, downwardly, left and right in various arcs to image the eye at different angles and locations It will be appreciated that the camera 200 may be positioned in any desired location to image a particular portion of the eye
- the fundus camera 200 also preferably includes a positioner to position the camera a desired distance from the eye
- the position includes a chin rest and a forehead rest which the subject to be examined rests their head against
- the camera 200 is then moved about the eye of the subject
- the outer surface 230 of the objective lens 226 is configured to be positioned between about 20 mm and 30 mm from the cornea of the eye to be examined
- the camera 200 may also include a target such as a needle or light source in which the subject looks at during the procedure By moving the target, the examiner can have the subject move their eyes to the desired position
- the positioner is used to position the subject in the desired location with the objective lens 226 about 25 mm from the cornea of the eye to be examined, but use of the positioner is not required
- the camera 200 is then moved into the desired location to image the desired portion of the eye and the camera is focused by adjusting the positioning of the relay lens 244
- the camera 200 advantageously can focus on various parts of the eye such as the cornea, anterior chamber, pupil and retina, and this increases the diagnostic capabilities of the camera
- the operator watches the monitor 250 to focus the image and when the image is focused, the operator may take one or more digital images of the eye which are stored in the storage device 242
- the storage device 242 is preferably a component of a computer system which may be configured, for example, to print the images, compare the stored images with other images, or manipulate the images by mapping, filtering, definition processing, etc
- the digital images can be immediately taken and the operator can continually view the images on the monitor 240 during the recording of the images by the camera system
- the fundus camera 200 is useful during a variety of medical procedures because the operator can see exactly the portion of the eye in which a procedure is to be performed
- the camera 200 may be used in conjunction with a laser for treatment of an eye pathology
- the camera 200 may be used to identify an eye pathology and it may be used as part of a targeting system for the laser or other medical tool or device
- the laser can be accurately aimed at the pathology and this decreases if not eliminates collateral damage to the tissues or structures surrounding the pathology
- conventional fundus cameras do not allow simultaneous imaging and alignment of the laser, and thus the laser may not be accurately aligned because the eye or pathology may move Thus, there is a much greater risk of collateral damage with a conventional fundus camera
- the camera 200 may also be used in connection with any type of device or tool for treatment of the eye, or the camera may also be only using for viewing the eye or for collecting data about the eye Further, the fundus camera 200 may be used with lasers or other medical instruments which pass through the lens, or the lens may be moved out of the way
Abstract
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU12039/00A AU1203900A (en) | 1998-10-15 | 1999-10-15 | Methods and apparatus for digital ocular imaging |
Applications Claiming Priority (8)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10439298P | 1998-10-15 | 1998-10-15 | |
US10689498P | 1998-10-15 | 1998-10-15 | |
US60/104,392 | 1998-10-15 | ||
US60/106,894 | 1998-10-15 | ||
US18671098A | 1998-11-05 | 1998-11-05 | |
US09/186,710 | 1998-11-05 | ||
US32566999A | 1999-05-27 | 1999-05-27 | |
US09/325,669 | 1999-05-27 |
Publications (3)
Publication Number | Publication Date |
---|---|
WO2000021432A1 WO2000021432A1 (en) | 2000-04-20 |
WO2000021432A8 WO2000021432A8 (en) | 2001-04-12 |
WO2000021432A9 true WO2000021432A9 (en) | 2001-10-11 |
Family
ID=27493388
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1999/023872 WO2000021432A1 (en) | 1998-10-15 | 1999-10-15 | Methods and apparatus for digital ocular imaging |
Country Status (2)
Country | Link |
---|---|
AU (1) | AU1203900A (en) |
WO (1) | WO2000021432A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9538949B2 (en) | 2010-09-28 | 2017-01-10 | Masimo Corporation | Depth of consciousness monitor including oximeter |
Families Citing this family (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2006013579A1 (en) * | 2004-08-02 | 2006-02-09 | Satish Chander Gupta | A retinal or fundus camera |
DE102007046210A1 (en) * | 2007-09-27 | 2009-04-02 | Carl Zeiss Meditec Ag | Arrangement and method for generating images with extended dynamics |
US20100157248A1 (en) * | 2008-12-22 | 2010-06-24 | Edwards R A | Color tinting of light in ophthalmic fiber optic illumination systems |
US9775545B2 (en) | 2010-09-28 | 2017-10-03 | Masimo Corporation | Magnetic electrical connector for patient monitors |
DE102010050693A1 (en) * | 2010-11-06 | 2012-05-10 | Carl Zeiss Meditec Ag | Fundus camera with stripe-shaped pupil division and method for recording fundus images |
WO2016057553A1 (en) | 2014-10-07 | 2016-04-14 | Masimo Corporation | Modular physiological sensors |
CN110236484B (en) * | 2019-06-28 | 2024-02-13 | 佛山科学技术学院 | Large-view-field fundus high-resolution imaging system |
CN111616800B (en) * | 2020-06-09 | 2023-06-09 | 电子科技大学 | Ophthalmic surgery navigation system |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5993001A (en) * | 1997-06-05 | 1999-11-30 | Joslin Diabetes Center, Inc. | Stereoscopic imaging system for retinal examination with remote examination unit |
-
1999
- 1999-10-15 WO PCT/US1999/023872 patent/WO2000021432A1/en active Application Filing
- 1999-10-15 AU AU12039/00A patent/AU1203900A/en not_active Abandoned
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9538949B2 (en) | 2010-09-28 | 2017-01-10 | Masimo Corporation | Depth of consciousness monitor including oximeter |
Also Published As
Publication number | Publication date |
---|---|
WO2000021432A1 (en) | 2000-04-20 |
WO2000021432A8 (en) | 2001-04-12 |
AU1203900A (en) | 2000-05-01 |
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