WO2005122874A1

WO2005122874A1 - Opthalmic camera and opthalmic camera adaptor

Info

Publication number: WO2005122874A1
Application number: PCT/AU2005/000880
Authority: WO
Inventors: Kanagasingam Yogesan; Gabriel Suplewski; Matthew David Spark; Ian Jeffrey Constable
Original assignee: Lions Eye Institute Limited
Priority date: 2004-06-18
Filing date: 2005-06-20
Publication date: 2005-12-29
Also published as: EP1773182A4; JP5226305B2; US8118428B2; US20080030679A1; CA2570933A1; JP2008502383A; EP1773182A1

Abstract

An ophthalmic camera (10) comprising a camera (12) having a lens (18) aligned with a second lens (16) and at least one illumination means (14).The illumination means (14) is capable of movement relative to the camera lens (18) so that the beam of light emitted by the illumination means (14) is able to be focused by the second lens (16) through the pupil onto the fundus. In another embodiment, the ophthalmic camera comprises a camera (52), an illumination means (54) and a beamsplitter (58). The camera (52) and the beamsplitter (58) form an alignment axis X and the illumination means (54) together with the beamsplitter (58) form an illumination axis Y perpendicular to the alignment axis X. The illumination means (54) is capable of movement relative to the illumination axis Y so that the beam of light reflected by the beamsplitter (58) towards the pupil (70) is substantially the same size as the pupil (70) to maximise the amount of light entering the pupil without impinging upon the iris to avoid contracting of the pupil (70).

Description

"Ophthalmic Camera and Ophthalmic Camera Adaptor"

Field of the Invention

The present invention relates to an ophthalmic camera and an ophthalmic camera adaptor. In particular, the invention relates to the optical arrangement that forms the basis for the ophthalmic camera and ophthalmic camera adaptor.

Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of Integers but not the exclusion of any other integer or group of integers.

Background Art

The following discussion of the background to the invention is intended to facilitate an understanding of the present invention. However, it should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was published, known or part of the common general knowledge of a skilled person in any jurisdiction as at the priority date of the application.

Images of the fundus of a patient's eye can degrade due to many factors. Such factors include:

• reflection of light from the cornea or iris;

• reflection of light from the walls of the ophthalmic lens; and • use of an incorrect level of illumination for the pupil colour of the patient's eye.

One method of overcoming some of the above problems is to use low level illumination devices. However, using such illumination devices, typically, reduces the field of view of the image and may not be appropriate for the pupil being examined. It is therefore an object of the present invention to provide an optical arrangement that reduces the level of reflection by one or more of the cornea, iris, or walls of the ophthalmic lens.

Disclosure of the Invention

In accordance with a first aspect of the invention there is provided an ophthalmic camera comprising: a camera having a lens; at least one illumination means; and a second lens;

wherein, the second lens is equal to or smaller than the camera lens and the centres of the second lens and camera lens are aligned to form an alignment axis;

and wherein said one illumination means is capable of linear movement along a radial axis of the camera lens and pivotal movement about a pivot point thereof, such that the circle of light emitted said one iliumiπation means can be adjusted towards or away the alignment axis to remain focused relative to the centre of the second lens.

Preferably, the second lens is an ophthalmic lens.

The illumination angle of the at least one illumination means may be adjustable. This may be an inherent characteristic of the at least one illumination means or achieved by an external element, such as a collimator. In this manner, the circle of light emitted by the at least one illumination means, at the point of intersection with the ophthalmic lens, is of a size that, when the light is focused by the ophthalmic lens onto a pupil, the angle of the focused light provides a wide field of view for the size of the pupil being examined.

The field of view of the camera lens may also be adjustable. Ideally, the field of view of the camera lens is restricted to the same size as the size of the pupil being examined. This may be achieved by means of an iris. The at least one illumination means may surround the circumference of the camera lens. Each illumination means is preferably equidistant from its adjacent illumination means to provide a homogenous light source. Preferably, the illumination means are solid state LEDs, however, light bulbs with appropriate focusing means may also be used.

The at least one illumination means may also be of variable intensity. In this manner, the at least one illumination means can adjust the level of illumination provided by the emitted circle of light to more appropriately accord with the colour of the pupil being examined. The level of intensity may be a function of a setting of the ophthalmic camera.

The camera preferably has a high sensitivity to low light. Ideally, the camera has a sensitivity level of <0.05 lux and/or a lens of 5 to 8mm in diameter.

The ophthalmic lens is preferably in the range of 20 to 90 dioptres, with 40 being considered optimal. The ophthalmic [ens may have an anti-reflective coating.

The ophthalmic lens may be capable of linear movement along the alignment axis to allow for focusing. Alternatively, other means of focusing the ophthalmic camera may be employed.

Ideally, the ophthalmic camera can be set to one or more settings. Each setting represents a pupil size. When a setting is changed, the at least one illumination means moves linearly along its radial axis to the position specified by the new setting and pivots about the radial plane until the circle of light emitted by the at least one illumination means is focused on the centre of the ophthalmic lens. Alternatively, the settings may be omitted and control of the linear and pivotal movement of the at least one illumination means may be by means of one or more manual controls. Both the setting control and the manual control may be expanded to further control the illumination angle of the at least one illumination means and/or the field of view of the camera lens.

Control of one or more of the linear and pivotal movement of the at least one illumination means, the illumination angle of the at least one illumination means and the field of view of the camera lens, may be controlled automatically by a control means in response to the estimated size of the pupil to be examined as determined by an automated measuring means.

The ophthalmic camera may also include magnification lenses. Each magnification lens may be associated with one or more settings, such that on choosing a setting, its associated magnification lenses are positioned within the optical axis of the camera and in-between the ophthalmic lens and the camera lens.

The camera may be colour or monochromatic, digital or analogue, as required.

Filters may be positioned in front of the camera lens and the at least one - illumination means, the filters being of opposite polarisation to each other.

In accordance with a second aspect of the present invention there is provided an ophthalmic camera comprising: a camera having a lens; at least one illumination means; and an ophthalmic lens;

wherein the ophthalmic lens is equal to or smaller than the camera lens and the centres of the ophthalmic lens and camera lens are aligned to form an alignment axis;

and wherein each of said one illumination means is positioned at a fixed distance along a radial axis of the camera lens and of fixed pivotal position about the radial plane incorporating radial axis and alignment axis, such that the circle of light emitted by said one illumination means is constantly focused relative to the centre of the ophthalmic lens and where, positioned in front of the camera lens and each of said one illumination means, are filters of opposite polarisation to each other.

In accordance with a third aspect of the present invention there is provided an ophthalmic camera comprising: a camera having a lens; at least one illumination means; a beam splitter; at least one focusing lens; and an ophthalmic lens;

wherein the ophthalmic lens is equal to or smaller than the camera lens and the centres of the ophthalmic lens and camera lens are aligned to form an alignment axis, the beam splitter being located along the alignment axis such that the ophthalmic lens is between the beam splitter and the camera lens;

and wherein at least one illumination axis, at right angles to the alignment axis as determined at the position of the beam splitter, is formed, each illumination axis including a focusing lens and an illumination means;

and wherein each illumination means is capable of linear movement along illumination axis and pivotal movement about the linear plane incorporating illumination axis and alignment axis, such that the circle of light emitted by said one illumination means is constantly focused relative to the centre of rts associated focusing lens, the light thereafter being focused on the beam splitter, such that the circle of light reflected by the beam splitter towards a pupil to be examined is of a size that the angle of the focused light provides a wide field of view for the size of the pupil being examined.

Preferably, the beam splitter is, ideally, a 50/50 beam splitter. However, beam splitters of other proportions may be used. Alternatively, a prism may be used in place of the beam splitter

In accordance with a fourth aspect of the present invention there is an ophthalmic camera adaptor incorporating the optics of any of the previous embodiments. The ophthalmic camera adaptor omits the camera.

In accordance with a fifth aspect of the present invention, there is provided a method of imaging a pupil comprising the steps of: moving an illumination means along a radial axis of a camera lens; and pivoting the illumination means such that the circle of light emitted by the illumination means can be focused relative to the centre of a second lens; wherein the centre of the second lens is in alignment with the centre of the camera fens and the second lens is equal to or smaller than the camera lens.

In accordance with a sixth aspect of the present invention, there is provided a method of imaging a pupil comprising: directing light emitted by an illumination means to a light focusing lens; and focusing the light onto a beam splitter, light reflected by the beam splitter being directed towards the pupil being substantially the same size as the pupil; wherein the centres of the beam splitter, light focusing lens and illumination means are aligned to form an illumination axis and the centres of a camera lens, second lens and the beam splitter are aligned to form an alignment axis perpendicular to the illumination axis and the second lens is equal to or smaller than the camera lens.

Brief Description of the Drawings

The invention will now be described, b ay of example only, with reference to the accompanying drawings, of which:

Figure 1a is a schematic of the optics of an ophthalmic camera and ophthalmic camera adaptor of a first embodiment of the present invention showing linear movement of the LED's.

Figure 1 b is a schematic of the optics of the ophthalmic camera and ophthalmic camera adaptor of the first embodiment, similar to Figure 1b but showing angular movement of the LED's. Figure 2 is an isometric view of the schematics of the optics of the ophthalmic camera and ophthalmic camera adaptor of the first embodiment of the present invention.

Figure 3 is a schematic of the optics of an ophthalmic camera and ophthalmic camera adaptor of a second embodiment of the present invention.

Figure 4 is a schematic of the optics of an ophthalmic camera and ophthalmic camera adaptor of a third embodiment of the present Invention.

Figures 5a and 5b are perspective views of an ophthalmic camera adaptor of the present invention.

Best Mode(s) for Carrying Out the Invention

The first embodiment of the the best mode invention for carrying out the invention is directed towards an ophthalmic camera apparatus 10, generally comprising a camera 12 highly sensitive to low light (ie. somewhere in the range of <0.05 lux). ' an illumination means in the form of a plurality of solid-state LEDs 14, and an ophthalmic lens 16 all contained within a housing (not shown). This arrangement is shown graphically in Figure 1.

The camera 12 has a camera lens 18 and so the ophthalmic lens constitutes a second lens of the apparatus 10. Ideally, the camera lens 18 has a diameter of 5- 8mm. The camera lens 18 provides for an adjustable field of view.

The plurality of LEDs 14 surround the circumference of the camera lens 18 and are linked to a control unit 20. The intensity of the light generated by LEDs 14 can be varied by way of the control unit 20.

Each LED 14 is equidistant to its adjacent LEDs 14. Each LED 14 also has an adjustable illumination angle.

As shown in Figures 1a and 2, LEDs 14 are able to move linearly along their respective radial axes (marked A through E), relative to the main optical axis X. As Shown in Figures 1b and 2, each LED 14 is also able to pivot about a pivot point thereof (A^* to E'), towards, or away from the camera lens 18, so that the illumination axis Y thereof can move either towards or away the point of intersection of the optical axis X with the ophthalmic lens 16, in order to compensate for linear movement of the LED along its respective radial axis A-E and corresponding displacement of the illumination axis Y relative to the optical axis X.

The ophthalmic lens 16 has an inner convex surface 22 that opposes the camera lens 18. The central axis of the camera lens 18 aligns with the central axis of the inner convex surface 22 to form an alignment axis, which constitutes the main optical axis X. Ideally, the ophthalmic lens 16 is of the same size as, or smaller than, the camera lens 18. An anti-reflective coating may be applied to the ophthalmic lens 16.

The ophthalmic lens is typically in the range of 20 to 90 dioptres, with 40 dioptres considered optimum. To allow for focusing of the ophthalmic lens 16, the ophthalmic lens 16 is capable of linear movement along optical axis X of the monochromatic camera 12.

The position of the LEDs 14, as well as the illumination angle of LEDs 14 and field of view of the camera lens 18, are all a function of the current setting of the ophthalmic camera apparatus 10. Each setting of the ophthalmic camera apparatus 10 represents a range of sizes of a pupil 24 of a patient with being examined with the apparatus. To elaborate,

• setting 1 is used for pupils of size less than 3mm;

• setting 2 is used for pupils having a size between 3-4mm; and • setting 3 is used for dilated pupils.

Upon choosing a setting: • The illumination angle of a beam of light 26 generated by each LED 14 along its illumination axis Y is restricted or enlarged, as appropriate, such that the circle generated by the beam of light 26 at the point of intersection with the ophthalmic lens 16 is of a size that, when the light is focused by the ophthalmic lens 16 onto the pupil 24, the angle of the focused light θ provides a wide field of view for the appropriate pupif 24 size.

• LEDs 14 move linearly along their respective radial axes (marked A through E) and pivot about their respective pivot point (marked A' through E') such that the centre of the circle generated by the beam of light 26 at the point of intersection with the ophthalmic lens 16 can be precisely adjusted with respect to the centre of the ophthalmic lens 16.

• The field of view of camera fens 18 is restricted to substantially the same size as the pupil 24 size associated with the setting.

This allows the same LEDs 14 to be used for pupils 24 of all sizes while negating the need to unnecessarily restrict the field of view of the camera lens 18 to avoid reflection from the cornea or iris. This also means that for larger size pupils 24, the angle of the focused light θ along the illumination axis Y is greater than the angle of the focused light θ generated in respect of smaller size pupils 24.

The second embodiment of the best mode is substantially similar to the first embodiment, where like numerals reference like parts, but involves the use of optical filters. As shown in Figure 3, a first filter 28 Is located along the optical axis X of the camera 12 at a position in front of camera lens 18. A second filter 30 is attached to each LED 14, such that the beam of light 26 emitted thereby passes through the second filter 30.

The first filter 28 is oppositely polarised to second filter 30. As the beam of light 26 reflects off the pupil 24 it enters the ophthalmic lens 18. On entering the ophthalmic lens 18, the polarisation of the beam of light 26 is reversed. However, as the beam of light 26 enters the ophthalmic lens 18, light that reflects off the two walls of the ophthalmic lens 18 will not be captured by the camera 12 due to the cross-polarisation effect of first and second filters 28, 30.

The third embodiment of the best mode is shown in Figure 4, and is directed towards an ophthalmic camera apparatus 50 comprising a digital camera 52 highly sensitive to low light (ie. somewhere in the range of <0.05 lux), a solid state LED 54, an ophthalmic lens 56, a beamsplitter 58 and a light focusing lens 60, all contained within a housing (not shown).

The digital camera 52 has a camera lens 62. Ideally, the camera lens 62 has a diameter of 5-8mm. The camera lens 62 provides for an adjustable field of view.

The ophthalmic lens 56 has an inner convex surface 64 that opposes the camera lens 62. The centre of the camera lens 62 aligns with the centre of the inner surface 64. Ideally, the ophthalmic lens 56 is of the same size as, or smaller than, the camera lens 62.

The ophthalmic lens 56 is typically in the range of 20 to 90 dioptres, with 40 dioptres considered optimum. To allow for focusing of the ophthalmic lens 56, the ophthalmic lens 56 is capable of linear movement along optical axis X of the digital camera 52.

Opposite the outer convex surface 66 of the ophthalmic lens 56, but still within the optical axis X of the digital camera 52, is beamsplitter 58. In this embodiment, beamsplitter 58 is a 50/50 beamsplitter, but beamsplitters of other proportions may be used.

Located substantially at a right angle to the optical axis X of the digital camera 52, as taken at the point of intersection with beamsplitter 58, is illumination axis Y. Located on illumination axis Y are light focusing lens 60 and solid state LED 54. Solid state LED 54 is capable of linear movement along illumination axis Y. Solid state LED 54 is also capable of pivotal movement about a pivot point that permits the illumination axis to be moved and adjusted relative to the optical axis X.

Solid state LED 54 has an adjustable illumination angle. The intensity of the light generated by the solid state LED 54 is also adjustable.

As with previous embodiments of the invention, the position of the solid state LED 54, the illumination angle of LED 54 and the field of view of the camera lens 62, are all a function of the current setting of the ophthalmic camera apparatus 50. Each setting of the ophthalmic camera 50 apparatus represents a range of sizes for the pupil 70 of a patient being examined with the apparatus. To elaborate, • setting 1 is used for pupils 70 of size less than 3mm;

• setting 2 is used for pupils 70 having a size between 3-4mm; and

• setting 3 is used for dilated pupils 70.

Upon choosing a setting:

• The illumination angle of light emitted by solid state LED 54 is restricted or enlarged, as appropriate, such that the circle of light reflected by the beamsplitter 58 towards pupil 70 is of a size that the angle of the focused light θ provides a wide field of view for the appropriate pupil 24 size..

• Solid state LED 54 moves linearly along illumination axis Y and pivots about the plane that includes illumination axis Y and optical axis X such that the centre of the circle of light reflected by the beamsplitter 58 towards pupil 70 is substantially aligned with or relative to the centre of the outer surface 66 of the ophthalmic lens 56. • The field of view of camera lens 62 is restricted to substantially the same size as the pupil 70 size associated with the setting.

This also means that for larger size pupils 70, the angle of the focused light θ is greater than the angle of the focused light θ generated in respect of smaller size pupils 70.

The fourth embodiment of the best mode is directed towards an ophthalmic camera adaptor 100. The ophthalmic camera adaptor 100 is shown in Figures 5a and 5b.

The ophthalmic camera adaptor 100 consists of a body 102. In the embodiment being described, body 102 is substantially rectangular in shape and has a rear face 104, two sides 106a, 106b and a front face 108.

Located centrally about rear face 104 is an aperture 110. Aperture 110 extends through the ophthalmic adaptor 100 such that the aperture 110 is also located centrally about front face 108. Situated adjacent aperture 110 is an interface contact 112.

Adjacent face 104 are two snap clips 114a, 114b. Snap clip 114a extends from side 106a, while snap clip 114b extends from side 106b. Each snap clip 114 has an internal recess 116a, 116b positioned such that, when appropriate pressure is applied, the snap clips 114 can flex towards aperture 110. Snap clips 114a, 114b are adapted to be releasably retained within grooves on the body of a camera (not shown) to which it is ultimately attached.

Surrounding front face 108, and extending along a portion of sides 106 towards rear face 104, is a rubber overmoulding 118. Rubber overmoulding 118 covers a portion 120 of each snap clip 114. Finger grips 122 are formed within the external surface 124 of rubber overmoulding 118 at a position substantially adjacent portion 120. The optics as described in any of the previous embodiments of the invention can be implemented In this ophthalmic adaptor 100 arrangement. The optics are connected to the interface contact 112 such that control of the optics is facilitated through the interface contact 112.

It should be appreciated by the person skilled in the art that the present invention is not limited to the above embodiments and that variations and modifications thereof are considered to be within the scope of the invention. In particular, the following modifications and variations fall within the scope of the invention:

• LEDs 14 may have a fixed illumination angle. In this arrangement, a collimator, or other like device, may be positioned in front of each LED 14. On choosing a setting, the collimator, or other like device, will operate to restrict or enlarge, as appropriate, the beam of light 26 generated by the LED 14 such that the circle generated by the beam of light 26 at the point of intersection with the ophthalmic lens 16 is of substantially the same size as the pupil 24 size associated with the setting. A similar collimator arrangement can be implemented in respect of the third embodiment of the invention.

• The ophthalmic camera 10, 50 and ophthalmic camera adaptor 100 may include magnification lenses. Each magnification lens is associated with at least one setting, such that, on choosing the setting, the magnification lens is positioned within the optical axis X of the monochromatic camera 12 and in-between the ophthalmic lens 16 and the camera lens 18.

• Camera 12 may be a monochromatic camera. Additionally, camera 12 may be a digital camera.

• LEDs 14, 54 can be replaced by a light focusing means and light bulb arrangement.

Beamsplitter 58 may be replaced with a prism arrangement. • The ophthalmic lens 16 may be replaced with any other type of lens.

• The plurality of LEDs 14 may be replaced with a single LED 14 disposed about the circumference of the camera lens 18. Alternatively, more or less LEDs 14 may be used than have been described herein.

• An alternate number of settings may be used than has been described herein. Alternatively, rather than having settings that move the LEDs 14 to predefined positions, the linear and pivotal movement of LEDs 14 may be facilitated through separate manual controls. Similarly, the illumination angle. of beam of light 26 and the field of view of camera lens 18 may be facilitated through separate manual controls.

• The linear and pivotal movement of LEDs 14, the illumination angle of beam of light 26 and the field of view of camera lens 18 may be facilitated through a single manual control.

• The intensity of the LEDs 14, 54 may be controlled by means of settings representing the various pupil colours. Alternatively, the intensity of the LEDs 14, 54 may be controlled by manual adjustment across the spectrum of intensities.

• An iris structure may be used to assist in limiting the field of view of the camera lens 18. The iris may be manually or automatically controlled.

• Control unit 20 may be adapted to control the linear and pivotal movement of LEDs 14, the illumination angle of beam of light 26 and the field of view of camera lens 18 based on the determined size of the pupil 24 to be examined. • The linear movement of the ophthalmic lens 18 as a means of focusing the image to be captured can be replaced by other focusing structures.

• The adaptor structure mentioned above can be replaced with any other structure incorporating the optical arrangement mentioned.

• The interface contact 112 may be omitted and in its place control unit 20 may be in-built into the adaptor.

It should be further appreciated by the person skilled in the art that features and modifications discussed above, not being alternatives or substitutes, can be combined to form yet other embodiments that fall within the scope of the invention described.

Claims

We claim:

1. An ophthalmic camera comprising: a camera having a lens; at least one illumination means; and a second lens; wherein the second lens is equal to or smaller than the camera lens and the centres of the second lens and camera lens are aligned to form an alignment axis; and wherein said one illumination means is capable of linear movement along a radial axis of the camera lens and pivotal movement about a pivot point thereof, such that the circle of light emitted by said one illumination means can be adjusted towards or away the alignment axis to remain focused relative to the centre of the second lens.

2. An ophthalmic camera according to claim 1 , wherein each illumination means surrounds the circumference of the camera lens and is equidistant from its adjacent illumination means.

3. An ophthalmic camera according to claim 1 or claim 2, including control means, the control means having a plurality of settings such that, when the setting of the control means is changed, said one illumination means moves linearly along its radial axis to the position specified by the new setting and pivots about the axial plane until the circle of light emitted by said one illumination means is focused relative to the centre of the second lens.

4. An ophthalmic camera according to claim 3, including automated measuring means, the automated measuring means operable to analyse a pupil being examined and change the setting of the control means to the most appropriate setting on the basis of the analysis of the pupil.

5. An ophthalmic camera according to any preceding claim, including a first filter located within the alignment axis and positioned in front of the second lens and a second filter attached to each illumination means such that light emitted by the illumination means passes through the second filter, the first filter being oppositely polarised to the second filter.

6. An ophthalmic camera comprising: a camera having a lens; an illumination means; a second lens; a beam splitter, and a light focusing lens; wherein the second lens is equal to or smaller than the camera lens and the centres of the second lens, camera lens and beam splitter are aligned to form an alignment axis, and the centres of the beam splitter, light focusing lens and the illumination means align to form an illumination axis perpendicular to the alignment axis such that light emitted by the illumination means is focused by the light focusing lens onto the beam splitter, the light reflected by the beam splitter along the alignment axis towards a pupil being substantially the same size as the pupil.

7. An ophthalmic camera according to claim 6, where the beam splitter is a 50/50 beam splitter.

8. An ophthalmic camera according to claim 6 or claim 7, where the illumination means is able to move linearly along the illumination axis such that the centre of the circle of light reflected by the beam splitter towards the pupil is substantially aligned with the centre of a first surface of the second lens.

9. An ophthalmic camera according to any one of claims 6 to 8, where the illumination means is able to pivot about a pivot point to permit the illumination axis to be moved and adjusted relative to said alignment axis.

10. An ophthalmic camera according to claim 8 or claim 9, as dependent on claim 8, including control means, the control means having a plurality of settings such that, when the setting of the control means is changed, said one illumination means moves linearly along the illumination axis to a predetermined position associated with the new setting.

11. An ophthalmic camera according to claim 10, including automated measuring means, the automated measuring means operable to analyse the pupil being examined and change the setting of the control means to the most appropriate setting on the basis of the analysis of the pupil.

12. An ophthalmic camera according to claim any preceding claim, where the second lens is an ophthalmic lens.

13. An ophthalmic camera according to any preceding claim where the lens has a diameter of between 5 and 8mm.

14. An ophthalmic camera according to any preceding claim, where the camera has a high sensitivity to low light.

15. An ophthalmic camera according to claim 14, where the camera has a sensitivity level of <0.05 lux.

16. An ophthalmic camera according to any one of claims 12 to 15, where the second lens is in the range of 20 to 90 dioptres.

17. An ophthalmic camera according to claim 16, where the second lens is 40 dioptres.

8. An ophthalmic camera according to any preceding claim including focussing means for focusing the second lens.

19.An ophthalmic camera according to claim 18, where the focusing means is means for allowing linear movement of the second lens along the alignment axis.

20.An ophthalmic camera according to any preceding claim, where the illumination angle of the illumination means is adjustable.

21. An ophthalmic camera according to claim 20, including at least one collimator, each collimator associated with an illumination means operable to adjust the illumination angle of the associated illumination means.

22. An ophthalmic camera according to any preceding claim where the field of view of the camera lens is adjustable.

23. An ophthalmic camera according to claim 22, including an iris, the iris operable to adjust the field of view of the camera lens.

24. An ophthalmic camera according to any preceding claim, where the intensity of the light generated by the illumination means is adjustable.

25. An ophthalmic camera according to any preceding claim, where the illumination means is a solid state light emitting diode.

26. An ophthalmic camera according to any one of claims 1 to 24, where the illumination means is a light bulb with associated appropriate focusing means.

27.An ophthalmic camera according to any preceding claim, where the second lens has an anti-reflective coating.

28. An adaptor for an ophthalmic camera having a body and a camera housed within the body, the adaptor comprising: optics for illuminating a subject within the optical axis of the camera in accordance with any one of claims 1 to 27; means for releasably engaging the body; and an aperture extending therethrough; wherein, when releasably engaged with the body, the aperture aligns with the optical axis such that least a portion of the optical axis of the camera is not obscured,

29. A method of imaging a pupil comprising the steps of: moving an illumination means along a radial axis of a camera lens; and pivoting the illumination means such that the circle of light emitted by the illumination means can be focused relative to the centre of a second lens; wherein the centre of the second lens is in alignment with the centre of the camera lens and the second lens is equal to or smaller than the camera lens.

30. A method of imaging a pupil according to claim 29, including the further step of: moving the illumination means along the radial axis to a predetermined position associated with a setting of a control means when the control means is set to the associated setting.

31. A method of imaging a pupil according to claim 30, including the steps of: analysing the pupil being examined; determining the most appropriate associated setting on the basis of the analysis of the pupil; and changing the setting of the control means to the most appropriate associated setting.

32. A method of imaging a pupil according to any one of claims 29 to 31, including the steps of: directing the circle of light through a first filter; and taking an image of the circle of light through a second filter of opposite polarisation to the first filter.

33. A method of imaging a pupil comprising: directing light emitted by an illumination means to a light focusing lens; and focusing the light onto a beam splitter, light reflected by the beam splitter being directed towards the pupil being substantially the same si2e as the pupil; wherein the centres of the beam splitter, light focusing lens and illumination means are aligned to form an illumination axis and the centres of a camera lens, second lens and the beam splitter are aligned to form an alignment axis perpendicular to the illumination axis and the second lens is equal to or smaller than the camera lens.

34. A method of imaging a pupil according to claim 33, including the step of moving the illumination means linearly along the illumination axis such that the centre of the circle of light reflected by the beam splitter towards the pupil is substantially aligned relative to the centre of a first surface of the second lens.

35. A method of imaging a pupil according to claim 33 or claim 34, including the step of pivoting the illumination means about the place that includes the optical axis and the illumination axis.

36. A method of imaging a pupil according to claim 34 or 35, as dependent on claim 34, comprising the further step of: moving the illumination means along the radial axis to a predetermined position associated with a setting of a control means when the control means is set to the associated setting.

37. A method of imaging a pupil according to claim 36, including the steps of: analysing the pupil being examined; determining the most appropriate associated setting on the basis of the analysis of the pupil; and changing the setting of the control means to the most appropriate associated setting.

38.A method of imaging a pupil according to any one of claims 29 to 37 further comprising the step of focussing the second (ens:

39.A method of imaging a pupil according to claim 38 including the step of linearly moving the second lens along the alignment axis to focus the second lens.

40. A method of imaging a pupil according to any one of claims 29 to 39, including the step of adjusting the illumination angle of the illumination means.

41. A method of imaging a pupil according to any one of claims 29 to 40, including the step of adjusting the field of view of the camera lens.

42. A method of imaging a pupil according to any one of claims 29 to 41 , including the step of adjusting the intensity of the light generated by the illumination means.