GB2584454A

GB2584454A - Lens-free ophthalmoscope

Info

Publication number: GB2584454A
Application number: GB1907916.9A
Authority: GB
Inventors: Hanif Armour Roger
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-06-04
Filing date: 2019-06-04
Publication date: 2020-12-09
Anticipated expiration: 2039-06-04
Also published as: GB201907916D0; GB2584454B

Abstract

The ophthalmoscope comprises a substantially planar body 2, 3 and a reflective portion 4 that, during use, protrudes from the body. Preferably a first light path (11, fig 5) extends along the body and is reflected by the reflective portion to a subject eye (20, fig 5), and a second light path (12, fig 5) extends parallel to the first for viewing light reflected back from the subject eye through a window 8 in the body. The non-reflective rear side 9 of the reflective portion may act as a baffle, reducing interference between light passing along the first and second light paths, and may be blackened or darkened. The reflective portion may be integral to the body, preferably hinged thereto. Also claimed is a blank of blank of creased rigid or semi-rigid material for forming the ophthalmoscope.

Description

LENS-FREE OPHTHALMOSCOPE

Field of the invention

This invention relates to a lens-free ophthalmoscope, such being the least complicated type of ophthalmoscope to manufacture and, hence, reasonably priced when compared with conventional lens-bearing ophthalmoscopes. Especially, but not exclusively, the invention relates to a lens-free ophthalmoscope of the type comprising a body having a reflective portion arranged, in use, to direct light along a first path away from the body toward a subject eye and to permit light reflected back from the subject eye to pass along a second path substantially parallel to the first path and through a window in the body for viewing the subject eye, the reflective portion also acting as a baffle to eliminate, or at least substantially reduce, interference between light passing along the first and second paths.

Background to the invention

Serious illnesses frequently cause changes in the retina that can be seen with an ophthalmoscope and may give a shortcut to the diagnosis. Thus, swelling of the optic disc in a child with an ear infection is a red flag sign that the infection has spread to the brain causing a cerebral abscess.

Unfortunately, conventional ophthalmoscopes are unnecessarily complicated for the average nonspecialist doctor, too heavy to be carried in a pocket, thereby reducing their availability for practice and for examining patients, and too expensive for medical students. Therefore, many doctors have abandoned the use of conventional ophthalmoscopes, believing it to be too specialised.

Prior Art

A lens-free ophthalmoscope comprising a tubular body and sloping roof attached to a light source is the subject of British Patent Number GB2387663 and is simpler in construction than conventional lens-bearing handheld ophthalmoscopes. To make its manufacture easier and even less expensive, it was modified by making substantially the entire head of the tubular body of the ophthalmoscope from a unitary folded blank, its being the subject of British Patent Application Number GB 1703293 filed on 1 March 2017 and published under Number GB2560879.

In known lens-free ophthalmoscopes, and indeed other, lens-bearing ophthalmoscopes, their bodies in which light sources are usually accommodated, are tubular and the reflective portions, if also acting as baffles, are housed within the tubular bodies.

In known lens-free ophthalmoscopes, the reflective portions acting as baffles maintain the parallel first and second light paths separate, to prevent, or at least substantially reduce, interference therebetween, hence at least substantially reducing any glare which might otherwise interfere with a user's view of a subject eye.

Present Invention An object of the present invention is to provide a lens-free ophthalmoscope which students, teachers or practitioners of medicine, veterinary medicine and biology, as well as paramedics, could make for themselves, thus restoring their confidence in fundus examination with an ophthalmoscope which is easily constructed, inexpensive and simple to use.

Another object of the invention is to provide a lens-free ophthalmoscope that allows an observer to gain a larger field of view of a subject eye than that which has previously been possible with existing lens-free ophthalmoscopes.

Accordingly, a first aspect of the invention resides in a body for a lens-free ophthalmoscope of the type described above, which body is generally planar and the reflective portion, in use, protrudes or is arranged to protrude therefrom.

A second aspect of the invention provides a body for a lens-free ophthalmoscope, which body comprises a reflective portion arranged to direct light, in use, along a first path away from the body toward a subject eye and to permit light reflected back from the subject eye to pass along a second path substantially parallel to the first light path and through a window in the body for viewing the subject eye, the reflective portion also acting as a baffle to eliminate, or at least substantially reduce, interference between light passing along the first and second light paths, wherein the body is generally planar and the reflective portion, in use, protrudes or is arranged to protrude therefrom.

A third aspect of the invention resides in a lens-free ophthalmoscope of the type described above, wherein the body is generally planar and the reflective portion, in use, protrudes or Is arranged to protrude therefrom A fourth aspect of the invention provides a lens-free ophthalmoscope comprising a body having a reflective portion arranged to direct light along a first path away from the body toward a subject eye and to permit light reflected back from the subject eye to pass along a second path substantially parallel to the first light path and through a window in the body for viewing the subject eye, the reflective portion also acting as a baffle to eliminate, or at least substantially reduce, interference between light passing along the first and second light paths, wherein the body is generally planar and the reflective portion, in use, protrudes or is arranged to protrude therefrom.

The body may also comprise a light source or be adapted to receive a light source, such as a collimated light source.

Any transfer of light from the first light path to the viewing window resulting in glare which might otherwise obscure and/or interfere with a user's view of the subject eye, is substantially eliminated or at least substantially reduced by the reflective portion protruding from the body, thereby providing the user with a clear view of the subject eye through the viewing window.

The reflective portion of the body is preferably planar and may be integral therewith, in which case, such portion may, in use, be moved, such as hinged, out of the plane of the body and, optionally, back into the plane of the body when not in use.

The body may be of any suitable sheet material, such as, cardboard or plastics sheet, cut and creased to provide, for example, the reflective portion being moved, such as hinged, out of the plane of the body to protrude therefrom. When so-moved, the reflective portion exposes the viewing window in the body.

The reflective portion is preferably mirrored using, say, a silver or other suitably reflective metal foil, in which case, the planar material from which the body can be made may be silver mirror card of, for example, 270 grams per square metre (gpm) weight.

The planar body may be lollipop-shaped with a head, possibly disc-shaped, and an elongate stem, the viewing window and the reflective portion being accommodated at or adjacent the head and the stem being arranged to receive a suitable light source, such as, an LED penlight, which may be detachably attached to the stem. The reflective portion is preferably rectangular and located in the centre of the disc, its having been folded about a crease line out of the plane of the disc through, say, forty-five degrees, to protrude therefrom.

Any residual glare from the edges of the reflective portion may be prevented, or at least substantially reduced, by having the non-reflective side of the reflective portion blackened or otherwise suitably darkened. Similarly, the area adjacent opposed edges of the viewing window on the side of the body remote from the reflective portion, when protruding therefrom, may be blackened or otherwise suitably darkened to reduce any residual glare.

If the body is made of, say, cardboard or other flexible or semi-stiff planar material, then at least the stem, and possibly the adjacent lower part of the disc below the viewing window, may be reinforced to receive and support a light source, such as, a penlight or torch.

The position of any light source with respect to the head, and hence to the reflective portion, of the body may be adjustable, to suit a user's requirements.

A fifth aspect of the invention resides in a lens free ophthalmoscope in accordance with the third aspect of the invention comprising a body in accordance with the first or second aspect of the invention and/or any modifications thereof, as described a.

A sixth aspect of the invention resides in a generally planar blank of rigid or semi-rigid sheet material cut and creased for erection into a generally planar body for a lens-free ophthalmoscope, the blank including a reflective portion which is movable out of the plane thereof to protrude therefrom and, in use, to direct light along a first path away from the body toward a subject eye and to permit light reflected back from the subject eye to pass along a second path substantially parallel to the first light path and through a window in the body for viewing the subject eye, the reflective portion in use also acting as a baffle to eliminate, or at least substantially reduce, interference between light passing along the first and second light paths.

The body so-erected from the blank may be adapted to receive a light source for directing light to the reflective portion and along the first light path.

In the third, fourth, fifth and sixth aspects of the invention, the viewing window may be rectangular, preferably square.

Yet another, seventh aspect of the invention provides a lens-free ophthalmoscope comprising a body having a head which incorporates a viewing window and a reflective component and which is mounted upon, preferably integrally with, a stem bearing or arranged to receive a light source, preferably collimated, for directing light along a light path to a subject eye via the reflective component, such as, for example, the arrangements described above in relation to the first, second, third and fourth aspects of the invention, wherein the positions of the body, and hence the viewing window, and light source are adjustable relative to one another.

Such an arrangement is not necessarily limited to the other aspects of the invention described herein but may also be incorporated in other types of lens-free ophthalmoscope.

In an embodiment of ophthalmoscope according to the sixth aspect of the invention, the ophthalmoscope comprises two parts, namely, a body and light source. Preferably, the elongate stem with which the light source, such as a penlight, is associated, is adjustably mounted lengthwise with respect thereto. The body can have a head, preferably circular and at the top of the stem, including a reflective component, such as, a right angled prism, for directing light from the light source along the first path to a subject eye, and also a viewing window through which light reflected back from the subject eye passes along a second path to an observer. Such window is preferably hemispherical but, as described above, may alternatively be rectangular, such as square, or circular.

Brief Description of the Drawings

In order that the various aspects of the invention may be more fully understood, embodiments thereof will now be described by way of example and with reference to the accompanying drawings in which: Figure 1 is an elevational front view of a blank from which the body of a lens-free ophthalmoscope in accordance with the first aspect of the invention, is erectable; Figure 2 is an elevational sectional side view of the head of the non-erected body blank of Figure 1; Figure 3 is an elevational sectional side view of the head of the body of a lens-free ophthalmoscope erected from the blank shown in Figures 1 and 2; Figure 4 is an elevational rear view of the head of the erected body of Figure 3; Figure 5 is a side elevational view of the erected ophthalmoscope of Figures 4 in use with a light source; and Figures 6A and 68 are respective front and side elevational views of another form of ophthalmoscope in accordance with the fifth aspect of the invention.

Detailed Description of the Drawings

Referring firstly to Figures 1 and 2 of the accompanying drawings, a body blank for a lens-free ophthalmoscope, indicated generally at 1, is cut from a stiff planar material, such as cardboard or plastics sheet, and comprises a head 2 and a stem 3. A generally square portion 4 is cut on three sides from the head 2 but hinged thereto by a normal crease 5 effectively constituting the fourth side of the square portion 4.

At least the front side of the hinged portion 4 is coated with a sheet 6 of reflective material, although in this embodiment practically the whole of the front side of the planar head 2 is coated with reflective sheet material 7 including the sheet 6 of the hinged portion On erection of the blank 1, the reflective portion 4 is hinged outwardly about the crease 5, as shown in Figure 3, to expose a viewing window 8 in the head 2 and, in use, to direct light from a collimated light source 40 along a first light path 11 toward a subject eye 20, as shown in Figure 5. Light reflected from the subject eye 20 along a second light path 12 generally parallel to the first light path 11, passes through the viewing window 8 into the eye 30 of an observer.

Because the edges of the reflective portion 4 could possibly produce in certain circumstances a penumbra-like effect, the non-reflective rear side 9 of the reflective portion 4 is painted black, a shown in Figure 4, to prevent, or at least substantially reduce, any scattered light from interfering with light passing along the second light path 12 and, possibly, light passing along the first light path 11. For the same reason, either side of the viewing window 8 on the rear side of the head 2 is blackened, for example, with black adhesive tape 9 which could overlap slightly the corresponding opposed edges of the window 8.

The simplicity of the inventive ophthalmoscope, described above and using Occam's law of removing all unnecessary detail, makes it easily and economically manufacturable by hand or machine and, hence, of low cost.

A square or other rectangular viewing window tends to make manual construction easier than making a circular viewing window and does not reduce the view through it.

Furthermore, the position of the viewing window or other aperture relative to the light paths in an ophthalmoscope is of crucial importance, as the sight and illumination paths must be parallel and coaxial or substantially so, to ensure a good view of a subject eye. This principle was not understood and not incorporated in ophthalmoscope design until the work of Purkinje, Babbage and Helmholtz. With a basic ophthalmoscope such as one in accordance with the invention, it is easier to achieve such requirement with a rectangular, preferably square, viewing window.

The ophthalmoscope body can be flattened for ease of portability and/or storage.

Also, an ophthalmoscope in accordance with the invention provides an immediate view of a subject eye without the need to calibrate it which is unlike traditional ophthalmoscopes yet provides a comparable view.

Turning now to Figures 6A and 6B of the accompanying drawings, here is shown an embodiment of a lens-free ophthalmoscope in accordance with the sixth aspect of the invention.

Thus, such an ophthalmoscope comprises a body, indicated generally at 101, including a generally planar head 102 integral with a stem 103. Detachably and adjustably mounted lengthwise to the stem 103 is a penlight light source 140 which is collimated and which directs light, via the mirrored surface 104 of a right-angled, prismatic block 105, along a first path 111 to a subject eye 120. Light reflected from the eye 120 along a second light path 112 generally parallel to the first light path 111, as shown in Figure 6B, passes through a hemispherical viewing window 108 into the eye 130 of an observer (not shown). As an alternative, the viewing window 108 may be square or otherwise rectangular, rather than hemispherical.

The light source 140 is detachably mounted to the stem 103 by a pair of clamps 150 which are such as to allow the body 101 of the ophthalmoscope to be adjusted lengthwise with respect to the light source 140. The extended condition of the body 101 with respect to the light source 140 is shown diagrammatically in dashed lines in Figures 6A and 6B.

Handheld ophthalmoscopes, including lens-free ones, can give a highly magnified view of a retina of, say, 15X, but with a restricted field of view of, say, 5-10 degrees. The closer the observer to the patient, the greater is the field of view. Thus, the extensibility of the lens-free ophthalmoscope in accordance with the fifth aspect of the invention, as described above, with its generally planar head 102 allows an observer to be placed comparatively closer to a patient, to provide a correspondingly and comparatively greater field of view than those exhibited by previous ophthalmoscopes.

After use, the head 102 can be retracted with respect to the light source 140, for ease of storage, portability and transportation.

Accordingly, it can be seen that the present invention in all its aspects described above, provides a lens-free ophthalmoscope having a generally planar body, as opposed to the generally tubular bodies of known ophthalmoscopes, including not only previously-known lens-free ophthalmoscopes, which can be pocket-portable and readily assembled from a unitary blank of sheet material at low cost, but also lens-bearing ophthalmoscopes.

Claims

Claims 1. A body for a lens-free ophthalmoscope, which body is generally planar and a reflective portion thereof, in use, protrudes or is arranged to protrude therefrom.
2. A body for a lens-free ophthalmoscope, which body comprises a reflective portion arranged to direct light, in use, along a first path away from the body toward a subject eye and to permit light reflected back from the subject eye to pass along a second path substantially parallel to the first light path and through a window in the body for viewing the subject eye, the reflective portion also acting as a baffle, in use, to eliminate, or at least substantially reduce, interference between light passing along the first and second light paths, wherein the body is generally planar and the reflective portion, in use, protrudes or is arranged to protrude therefrom.
3. A body as claimed in claim 1 or 2 comprising or adapted to receive a light source.
4. A body according to claim 3, wherein the light source is collimated.
5. A body according to claim 2, 3 or 4, wherein the reflective portion is planar.
6. A body according to any of claims 2 to 5, wherein the reflective portion is integral therewith, preferably hinged thereto.
7. A body according to any of claims 2 to 6, wherein the reflective portion is movable in and out of the plane thereof.
8. A body according to any of claims 2 to 7, wherein the reflective portion is movable out of the plane thereof to expose the viewing window.
9. A body according to any of claims 2 to 8 which is of a sheet material.
10. A body according to claim 9, wherein the sheet material is cardboard or a plastics material.
11. A body according to any of claims 2 to 11, wherein the reflective portion is mirrored.
12. A body according to claim 11, wherein the reflective portion is of metal foil or silver mirror card.
13. A body according to any of claims 2 to 12 which is lollipop-shaped with a head and an elongate stem, the viewing window and reflective portion being accommodated at or adjacent the head and the stem being arranged to receive a light source, preferably detachably.
14. A body according to claim 13, wherein the lollipop-shaped head is disc-shaped.
15. A body according to claim 14, wherein the reflective portion is rectangular and located in the centre of the disc-shaped head, its having been folded about a crease line out of the plane of the disc-shaped head through, say, 45 degrees, to protrude therefrom.
16. A body according to claim 13, 14 or 15 which is of a flexible or semi-rigid planar material, wherein at least the elongate stem is reinforced to receive and support a light source thereon.
17. A body according to claim 16, wherein the lower part of the head adjacent the stem is reinforced.
18. A body according to any of claims 13 to 17 comprising a light source supported upon the stem, the position of the light source with respect to the head being adjustable.
19. A body according to claim 18, wherein the light source is collimated.
20. A body according to any of claims 2 to 19, wherein a non-reflective side of the reflective portion is blackened or otherwise darkened.
21. A body according to any of claims 2 to 20, wherein the area adjacent opposed edges of the viewing window on the side of the body remote from the reflective portion, when protruding therefrom, is blackened or otherwise darkened.
22. A lens-free ophthalmoscope comprising a body which is generally planar and of which a reflective portion, in use, protrudes or is arranged to protrude therefrom.
23. A lens-free ophthalmoscope comprising a body having a reflective portion arranged to direct light along a first path away from the body toward a subject eye and to permit light reflected back from the subject eye to pass along a second path substantially parallel to the first light path and through a window in the body for viewing the subject eye, the reflective portion also acting as a baffle, in use, to eliminate, or at least substantially reduce interference between light passing along the first and second paths, wherein the body is generally planar and the reflective portion, in use, protrudes or is arranged to protrude therefrom.
24. An ophthalmoscope according to claim 22 or 23, wherein the body comprises or is adapted to receive a light source.
25. An ophthalmoscope according to claim 24, wherein the light source is collimated.
26. An ophthalmoscope according to claim 23, 24 or 25, wherein the reflective portion is planar.
27. An ophthalmoscope according to any of claims 23 to 26, wherein the reflective portion is integral with the body, preferably hinged thereto.
28. An ophthalmoscope according to any of claims 23 to 27, wherein the reflective portion is movable in and out of the plane of the body.
29. An ophthalmoscope according to any of claims 23 to 28, wherein the reflective portion is movable out of the plane of the body to expose the viewing window therein.
30. An ophthalmoscope as claimed in any of claims 23 to 29, wherein the body is of a sheet material.
31. An ophthalmoscope as claimed in claim 30, wherein the sheet material is cardboard or a plastics material.
32. An ophthalmoscope according any of claims 23 to 31, wherein the reflective portion is mirrored.
33. An ophthalmoscope according to claim 32, wherein the reflective portion is of metal foil or silver mirror card.
34. An ophthalmoscope according to any of claims 23 to 31, wherein the body is lollipop-shaped with a head and an elongate stem, the viewing window and reflective portion being accommodated at or adjacent the head and the stem being arranged to receive a light source, preferably detachably.
35. An ophthalmoscope according to claim 34, wherein the lollipop-shaped head is disc-shaped.
36. An ophthalmoscope according to claim 35, wherein the reflective portion is rectangular and located in the centre of the disc-shaped head, the reflective portion having been folded about a crease line out of the plane of the disc-shaped head through, say, 45 degrees, to protrude therefrom.
37. An ophthalmoscope according to claim 34, 35 or 36, wherein the body is of a flexible or semi-rigid planar material and at least the elongate stem is reinforced to receive and support a light source thereon.
38. An ophthalmoscope according to claim 37, wherein the lower part of the body head adjacent the stem is reinforced.
39. An ophthalmoscope according to any of claims 34 to 38 comprising a light source supported, possibly detachably, upon the stem, the position of the light source with respect to the head being adjustable.
40. An ophthalmoscope according to claim 39, wherein the light source is collimated.
41. An ophthalmoscope according to any of claims 23 to 40, wherein a non-reflective side of the reflective portion is blackened or otherwise darkened.
42. An ophthalmoscope according to any of claims 23 to 41, wherein the areas adjacent opposed edges of the viewing window on the side of the body remote from the reflective portion, when protruding therefrom, is blackened or otherwise darkened.
43. A generally planar blank of rigid or semi-rigid sheet material cut and creased for erection into a generally planar body for a lens-free ophthalmoscope, the blank including a reflective portion which is movable out of the plane thereof to protrude therefrom and, in use, to direct light along a first path away from the body toward a subject eye and to permit light reflected back from the subject eye to pass along a second path substantially parallel to the first light path and through a window in the body for viewing the subject eye, the reflective portion in use also acting as a baffle to eliminate, or at least substantially reduce, interference between light passing along the first and second light paths.
44. A blank according to claim 43, wherein a body erected therefrom is adapted to receive a light source for directing light to the reflective portion and along the first light path.
45. A lens-free ophthalmoscope comprising a body having a head which incorporates a viewing window and a reflective component and which is mounted upon, preferably integrally with, a stem bearing or arranged to receive a light source, preferably collimated, for directing light along a light path to a subject eye via the reflective component, wherein the positions of the body, and hence the viewing window, and light source are adjustable relative to one another.
46. An ophthalmoscope according to claim 45, wherein the reflective component is a right-angled prism.
47. An ophthalmoscope according to claim 45 or 46, wherein the viewing window is hemispherical, spherical, rectangular or square.
48. An ophthalmoscope according to claim 45, 46 or 47, wherein the body is generally planar.