WO2011042721A1

WO2011042721A1 - Improvements in and relating to ophthalmic instruments

Info

Publication number: WO2011042721A1
Application number: PCT/GB2010/051635
Authority: WO
Inventors: Adrian Carl Beasley
Original assignee: Keeler Limited
Priority date: 2009-10-05
Filing date: 2010-09-30
Publication date: 2011-04-14
Also published as: GB2474082A; GB0917420D0; GB2474082B

Abstract

An ophthalmic instrument such as an indirect ophthalmoscope comprises viewing means through which, in use, an eye under examination is viewed by a user of the device; image capture means (2.5) for capturing an image, corresponding to the view seen through the viewing means, of said eye and display means for displaying said image, wherein the display means comprises a hand held viewing screen (4; 104).

Description

Improvements in and relating to Ophthalmic Instruments Field of the Invention

This invention relates to an ophthalmic instrument and more particularly, but not exclusively, to an indirect ophthalmoscope for use in teaching.

Background to the Invention

Indirect ophthalmoscopy, in particular binocular indirect ophthalmoscopy, is a procedure commonly used to examine the fundus of an eye. The technique involves using a hand held condensing lens which is placed between the user and the subject. This lens produces an aerial image of the retina that is viewed through the observation system of the ophthalmoscope.

Typically, an ophthalmoscope is head mounted and comprises a light source from which a beam is projected towards the eye under examination via the hand held condensing lens. The ophthalmoscope includes viewing means, usually binocular viewing optics through which an examiner or user can obtain a view of the image of the fundus of the eye under examination.

A teaching ophthalmoscope is arranged to provide one or more students not wearing the ophthalmoscope with a view corresponding to the image being seen by the examiner/user, so that these students can see not only how the examiner/user is operating the instrument, but also how the examiner/user interprets the images being viewed through the instrument. To that end, indirect ophthalmoscopes may offer a "teaching mirror" comprising a semi-silvered mirror placed in front of the viewing optics to allow a third person to see what the examiner/user sees. However, for this system to work the third person must stand next to the user and mimic his/her movements. Also since the image is split between the user and the third person both images are of a reduced intensity, and only two additional people can view the reflected image (one on each side of the ophthalmoscope). It is also known to equip an ophthalmoscope with a camera that detects an image reflected from a half silvered mirror in front of the viewing optics and transmits this image to a computer for display. In this situation, the position of each student is less critical, more students can see the detected image and the reduction intensity can (at least in the displayed image) be obviated by the camera settings or by subsequent processing of the detected images. This also means that a greater portion of light can reach the viewing optics. However, this apparatus is relatively expensive since it requires a computer. Furthermore, the position of the display of the computer might not always be entirely suitable for a student, who may need to have a simultaneous view of the user and the detected image to be able to appreciate how the user is operating the instrument in order to obtain that image.

Summary of the Invention

According to the invention there is provided an ophthalmic instrument comprising viewing means through which, in use, an eye under examination is viewed by a user of the device; image capture means for capturing an image, corresponding to the view seen through the viewing means, of said eye and display means for displaying said image, wherein the display means comprises a hand held viewing screen.

A hand held viewing screen is a screen which is light enough to be easily held in one or both hands for the duration of the use of the instrument (in a teaching session), and to that end is preferably a weight not exceeding 250g.

Furthermore, in order to be hand held, the screen needs to be of a size large enough to enable the displayed image to be readily seen, but not so large as to be unduly cumbersome, for example by obscuring the student's direct view of the examination being conducted by the user or being too difficult to hold in either or both hands.

Thus the screen is preferably rectangular, having a diagonal dimension in the range of 9- 18cm. Preferably, the screen is separate from the instrument. Preferably, the image capture means comprises a camera, preferably a video camera.

The video camera gives the student a real time display on the screen, corresponding to what is being seen by the user of the instrument, and in this case, the screen functions as a hand held, non inverting teaching mirror.

Preferably, the viewing screen is a dedicated display device. Such a device, unlike a computer, does not need to boot-up, but instead can operate almost immediately after being switched on. In addition, the need to include a computer in the apparatus (and the additional costs associated therewith) is avoided.

The display means is preferably physically connected to the image capture means by a cable along which image data from the image capture means is transmitted to the display means.

This provides an easy method of connection of the camera and display means. If the display means were not hand held, there would be a risk that the connecting cable would act as a tether which could impede the movement of the user. However, a student holding the display means of the present invention is likely to ensure, in use, this does not happen.

Advantageously, the display means in this instance includes power supply means for supplying electrical power for operating both the display means and the image capture means. Thus the power supply for the camera does not have to be carried on the instrument.

Conveniently, where the image capture means comprises a video camera, this is operable to generate a composite video signal.

Preferably, said cable is a USB cable, the video signal being transmitted along a connection not usually used in USB, for example pin 5 of the mini-B type USB connector.

Preferably, the display means comprises an LCD or OLED display screen. Preferably, the viewing means comprises viewing optics, constituted by an arrangement of optical elements for forming a focussed image of the eye under examination.

The display means may to advantage include a solid state digital video recorder for recording the images/footage captured by the image capture means. A example of such a display means is the HQR-2 Mpeg 2/4 digital video recorder supplied by dogcam. This provides power to the image capture means (video camera in this case), a screen to view realtime footage and the facility to record this onto a compact flash card.

Such a screen has numerous possible applications such as tele medicine where the images/videos wiH be sent to a third party for analysis/diagnosis; record keeping where the recorded images/video are kept for comparison to subsequent examinations for monitoring progress of condition or effectiveness of treatment; database accumulation to provide reference images/videos across a large number of patients; or record keeping as support to a doctor later chaiienged to have not identified a condition which develops later.

Consequently this screen need not necessarily i3e used to dispiay images to students, but could instead be used simply to enabie the user to monitor the footage being recorded. To that end, the display means may to advantage include means for mounting and retaining the screen on the user's forearm.

Where the instrument is an indirect ophthalmoscope, the screen can thus be situated adjacent the hand held lens so that the detected image can be viewed through the ophthalmoscope's viewing o tics.

To that end the display means may be attached to a strap or band (for example similar to the type of band that attaches a personal music player to the arm). Preferably, the display means is one of a plurality of such display means connectable in series so that all the display means receive the same signal from the image capture means.

Thus, in use, a first display means may be connected directly to the image capture means, a second to the first display means and each remaining display means (if any) to the previous display means.

In an alternative arrangement, the camera may include a wireless transmitter for transmitting a video signal for receipt by a wireless receiver on the or each display means.

In this case, power for the camera may be provided by a battery pack on the back of the instrument. The video signal will feed a composite video repeater or be connected to a microprocessor based system (such as the Gumstix stand alone computer) for digitised transmission.

Brief Description of the drawings

The invention will now be described by way of example only, with reference to the accompanying drawings in which: -

Figure 1 is an isometric view of a first embodiment of instrument in accordance with the invention;

Figure 2 is an isometric view of a second embodiment of instrument in accordance with the invention;

Figure 3 comprises a block circuit diagram of some of the components of the instrument shown in Figure 2;

Figure 4 is a similar diagram of a hand held screen for use with the instrument; and Figure 5 is an isometric view showing a modification to the first embodiment. Figure 6 is a schematic side view of viewing optics and illumination optics of either embodiment of the instrument; and

Figure 7 is a schematic view of part of the illumination optics. Detailed Description

With reference to Figure 1, the first embodiment of instrument in accordance with the invention comprises an indirect ophthalmoscope generally referenced 1 having a camera connected by a USB cable 2 to a hand held LCD screen 4. The ophthalmoscope 1 is attached to the front of a headband 6 which enables the instruments mounted on the head of a user. The rear of the headband 6 carries a battery pack 8 which provides the power for operating a light source in the ophthalmoscope 1. The intensity of light emitted by that source can be controlled by an intensity control 10 on the headband 6.

The ophthalmoscope 1, headband 6, battery pack 8 and control 10 constitute a product already supplied by the existing applicant under the Trade Mark KEELER VANTAGE PLUS LED DIGrrAL. The ophthalmoscope 1 comprises a housing 12 in the general shape of an inverted T. The housing contains illumination optics (including the light source mentioned above) and left and right eye viewing optics. The viewing optics constitute a viewing means through which, in use, an eye under examination is viewed.

The illumination optics are housed within the vertical stem of the housing 12 and comprise the light source and an angled mirror 209 (Fig.6) positioned under the light source to reflect light from the latter out through a window 14 in the front face of the housing. The mirror is positioned immediately above viewing optics 21 1 (Fig. 6, 7) contained within the cross-piece 16 of the housing 12. Two side controls 18 and 20 enable the angle of that mirror to be adjusted.

The illumination and viewing optics (and associated controls) of the instrument are as described in the applicant's US Patent Specification No. US 6280033, the contents of which are incorporated herein by reference. An angled half silvered mirror 22 is situated in front of the viewing optics on a mount which enables the angle of the mirror 22 to be adjusted by means of two side controls 24 and 26. The mirror 22 reflects light incident thereon up into a digital camera 25 situated in the stem of the housing 12 above the mirror 22. The adjustment provided by the controls 24 and 26 enables the user of the ophthalmoscope to adjust the field of view of the image detected by the camera so that it coincides as far as possible with what is being seen by the user through the viewing optics.

In use, 30% of the light is reflected up into the camera, the remaining 70% passing to the viewing optics, so that the mirror does not unduly degrade the image seen through the viewing optics.

The camera is a USB2 Powered Board camera which, as indicated above, forms part of the current applicant's exiting VANTAGE PLUS DIGITAL (TM) ophthalmoscope. The camera has a USB socket via which it is connected to a corresponding USB connector at one end of the cable 2. A similar connector is provided at the other end of the cable 2 and is plugged into the corresponding socket in the top of the hand held screen 4. The screen 4 contains a further USB socket (not shown) which enables a number of such screens to be 'daisy chained', i.e. connected together in series so that they receive the same video signal from the camera in the instrument 1.

The screen 4 includes a rechargeable 3.6V battery pack (not shown) that is connected to the USB power connection of the socket connected to the cable 2. The battery pack is connected to a switch mode converter that provides a 5V rail to power the display and head off to the headset via pin 5 of the USB socket. The camera has power terminals which are connected to the corresponding connections in the socket in the housing 1 , so that the power for operating the camera is supplied from the battery pack in the hand held screen 4 via the cable 2.

The screen 4 is generally rectangular, having the following external dimensions:

Width 85mm; length 60mm; thickness 5mm. The screen 4 can be connected to a PC or USB hub via the USB socket and this enables the battery pack in the screen 4 to be re-charged, from an external power source.

The camera produces a composite video signal which is supplied to the screen 4 along a normally unused connection on the USB connector, in this case pin 5. The screen 4 includes a video driver which is also powered by the battery pack, and which accepts the composite video signal and causes the LCD screen to display the images represented by the signal.

The composite video signal that is received by the screen 4 is also split so that it can in addition be fed to the second USB socket in the screen 4 to allow for the series connection described above.

As can be seen from Figure 1 , the headband 6 includes a pair of cable clips 7 and 9 either of which can accept the cable 2.

In use, the user will operate the ophthalmoscope 1 in the usual way, whilst the image received by the camera is viewed by a student on the screen 4. The image will correspond to the binocular image seen by the user. The screen 4 is of a size which is such that it can be conveniently held, the image can be properly seen, but the screen does not obscure the student's view of the user, so that the student can appreciate the adjustments being made to the instrument to achieve the view being seen on the screen 4. The student can also position the screen 4 so that the user and the image can be viewed simultaneously.

The embodiment of instrument shown in Figure 2 is similar in many respects to the first embodiment, and corresponding features are denoted by the references of Figure 1 raised by 100.

In this case, however, the ophthalmoscope 101 differs from the VANTAGE PLUS DIGITAL (™) in that it includes a wireless RF transmitter that modulates the composite video signal generated by the camera onto a RF carrier wave as a digital video stream (such as one according to IEEE802.i l) which is then wirelessly transmitted to a corresponding receiver in the screen 104. In this case, the power needed to operate the camera and modulation and RF transmission circuitry is obtain from the battery pack 108.

The battery pack shown in Figure 3 is connected to the camera 25 and to a video compressor and transmitter 150 which includes a mini 5.8GHz transmitter connected to an omni-directional whip antenna. An example of a suitable transmitter is the TMX-5808 produced by Videocom Technology. The composite video signal produced by the camera 25 is sent to the video compressor and transmitter 150 which converts the composite signal into a digital data stream representative of the video footage and then modulates the digital stream onto an RF carrier wave signal for transmission via the antenna.

This signal is received by a receiver 152 in the hand held screen (see Figure 4) the power for operating which is obtained from a battery 154 within the screen. An example of such a receiver is the RMX-5808LG mini 5.8GHz receiver produced by Videocom Technology. The receiver demodulates the signal and then converts the digital data stream back into a composite video signal proceeding to the driving circuitry for the display screen 156.

Figure 5 shows an ophthalmoscope which is also intended for use with a hand held screen connected to the ophthalmoscope along a USB cable 158. The ophthalmoscope is identical to that shown in Figure 1 save for the inclusion of two LED screens 160 and 162. The other components of the ophthalmoscope have been denoted by the same reference numerals as are used in Figure 1. Thus each of the LCD screens sits above one of the eye pieces of the binocular viewing optics, on top of the crosspiece 16 of the housing 12. The ophthalmoscope also includes driving circuitry (not shown) for operating the screens 160 and 162 and the output of the camera is split so that the composite video signal is fed to the screens as well as to the USB cable 158. In front of each screen is provided a converging lens that enables the user to focus on the image on the screen at a close distance. It will be appreciated that the screens allow the user easily to check whether the image detected by the camera corresponds to what is being viewed through the viewing optics. Power for operating the screens 162 and 160 can be obtained from the battery pack within the hand held screen or alternatively from the battery pack 8. With reference to Figures 6 and 7, the illumination optics comprise a light bulb or LED 207, at the top of the housing 12, and an angled mirror 209 positioned underneath the light source so as to reflect light from the latter out through the window 14 in the front face of the housing 12. The mirror is positioned immediately above the viewing optics 21 1 (situated in the cross-piece of the housing).

With reference to Fig.7, the viewing optics 211 comprise a pair of laterally spaced mirrors 213 and 215 which are mounted on triangular mirror blocks (217 and 219). The mirrors 213 and 215 are angled so as to direct light travelling into the viewing optics through the mirror 22 (along the viewing paths 221 and 223) horizontally outwards to the reflective surfaces of the mirrors 225 and 227 mounted on triangular mirror blocks 229 and 231 which have apertures (233 and 235) to allow the light to reach the mirrors 225 and 227. Further apertures (237 and 239) in the blocks 229 and 231 enable the light reflected by the mirrors 225 and 227 to travel to eyepieces (not shown) situated behind the platform 241 on which the mirror blocks are mounted. The spacing between the mirrors can be adjusted in order to adjust the stereopsis of the ophthalmoscope.

It will be appreciated that many variations to the instrument designs are possible without departing from the scope of the invention as defined in the claims. Thus, for example, the viewing means can comprise any suitable arrangement of optical and/or electronic elements that can form an image of the eye under examination for viewing by the user. Thus the viewing means could comprise a camera (possibly the existing camera) in the ophthalmoscope, the output of which camera is displayed on one or more viewing screens within the user's field of view (e.g. behind the eye pieces of the ophthalmoscope).

Claims

1. An ophthalmic instrument comprising viewing means through which, in use, an eye under examination is viewed by a user of the device; image capture means for capturing an image, corresponding to the view seen through the viewing means, of said eye and display means for displaying said image, wherein the display means comprises a hand held viewing screen.

2. An ophthalmoscope according to claim 1, in which the hand held screen is separate from the instrument.

3. An instrument according to claim 1 or claim 2, in which the hand held viewing screen is of a weight not exceeding 250g.

4. An instrument according to any of the preceding claims, in which the hand held viewing screen is rectangular, having a diagonal dimension in the range of 9- 18 cm.

5. An instrument according to any of the preceding claims, in which the image capture means comprises a camera.

6. An instrument according to claim 5, in which the camera is a video camera.

7. An instrument according to claim 6, in which the video camera gives a real time display on the hand held viewing screen, corresponding to what is being seen by the user of the instrument, the hand held viewing screen functioning as a hand held, non inverting teaching mirror.

8. An instrument according to any of the preceding claims, in which the hand held viewing screen is a dedicated display device.

9. An insrument according to any of the preceding claims, in which the display means is physically connected to the image capture means by a cable along which image data from the image capture means is transmitted to the display means.

An instrument according to claim 9, in which the display means includes power supply means for supplying electrical power for operating both the display means and the image capture means.

11. An instrument according to claim 9 or claim 10, in which said cable is a USB cable.

12. An instrument according to claim 11, in which the camera is a video camera, the video signal being transmitted via pin 5 of the mini-B type USB connector.

13. An instrument according to any of the preceding claims, in which the hand held display screen comprises an LCD or OLED display screen.

An instrument according to any of the preceding claims, in which the hand held display screen includes a solid state digital video recorder for recording the images/footage captured by the image capture means.

15. An instrument according to claim 14, in which the display screen includes means for mounting and retaining the screen on the user's forearm.

16. An instrument according to claim 15, in which a display screen is attached to a strap or band via which the screen can be mounted and retained on the user's forearm.

An instrument according to any of the preceding claims, in which the display means is one of a plurality of such display means connectable in series so that all the display means receive the same signal from the image capture means.

18. An instrument according to any of claims 1 to 8, in which the camera includes a wireless transmitter for transmitting a video signal for receipt by a wireless receiver on the or each display screen. An instrument according to any of the preceding claims, in which the instrument comprises an indirect ophthalmoscope.