Improvements in or relating to slit lamps

Abstract

There is disclosed a slit height adjustment mechanism for use in a remote digital slit lamp. The mechanism comprises a drive means, a filter plate movable along at least one defined movement path by the drive means and an aperture in the filter plate having a primary axis aligned with the movement path of the filter plate and a secondary axis, transverse to the primary axis defining slit height. The dimension of the aperture along the secondary axis varies along the length of the primary axis such that moving the filter plate along the movement path enables the height of a light beam shone through the aperture to be adjusted. Also disclosed is a slit width adjustment mechanism and a light conditioning apparatus for use in a remote digital slit lamp.

Description

[0001] IMPROVEMENTS IN OR RELATING TO SLIT LAMPS

[0002] Technical Field of the Invention

[0003] The present invention relates to digital slit lamps. Particularly, but not exclusively, it relates to remote digital slit lamps (RDSLs).

[0004] Background to the Invention

[0005] Slit lamps are well known in the fields of ophthalmology and optometry. Conventional slit lamps comprise a light source which produces a high intensity light beam, and a mechanism by which an operator (typically an ophthalmologist or optician) can adjust the dimensions of a slit through which the light is shone, allowing the properties of the light beam to be altered.

[0006] Conventional slit lamps are manually controlled by an operator in the same room as the slit lamp. Amongst other things, the operator is able to alter the intensity of the light, and the height and width of the slit, so as to enable the operator to examiner various aspects of a patient’s eye. In conventional slit lamps, the operator is able to manually control the height and width of the slits by turning respective knobs of the slit lamp.

[0007] This poses an issue for digital slit lamps, as manual turning of the knobs is no longer possible. This means that a digital mechanism must be used, which can introduce discrepancies between the desired slit width or height of the operator and that which the slit lamp actually implements. This can be caused by myriad factors, including poor calibration of the slit lamps, and the build-up of mechanical tolerance of the slit lamp’s internal mechanisms.

[0008] For non-remote digital slit lamps, this issue can be mitigated by the operator adjusting the slit width or height such that they can see that the desired result, either ‘freehand’ or using an external instrument. Conversely, this issue is magnified for RDSLs, as there is no in-room operator who can mitigate these known issues.

[0009] It is the object of the present invention to at least partially overcome and / or alleviate these known issues in relation to RDSLs.

[0010] Summary of the Invention According to a first aspect of the present invention, there is provided a slit height adjustment mechanism for use in a remote digital slit lamp (RDSL), the slit height adjustment mechanism comprising: a drive means, a filter plate movable along at least one defined movement path by the drive means; an aperture in the filter plate having a primary axis aligned with the movement path of the filter plate and a secondary axis, transverse to the primary axis defining slit height; wherein the dimension of the aperture along the secondary axis varies along the length of the primary axis, such that moving the filter plate along the movement path enables the height of a light beam shone through the aperture to be adjusted.

[0011] According to a second aspect of the present invention, there is provided a slit width adjustment mechanism for use in a remote digital slit lamp (RDSL), the slit width adjustment mechanism comprising: a pair of slit plates defining a slit therebetween, a drive means, a cam connected to the drive means, the cam comprising a pair of abutting members arranged diametrically opposite to each other, a pair of followers each biased toward the centre of the cam, each follower being arranged to abut one of the abutting members of the cam so as to follow the movement of the corresponding abutting member, each follower comprising one of the slit plates, and characterised in that a shim is placed between the slit plates to define a minimum slit width.

[0012] According to a third aspect of the present invention, there is provided a light conditioning apparatus for use in a remote digital slit lamp (RDSL) comprising a slit height adjustment mechanism according to the first aspect of the present invention and / or a slit width adjustment mechanism according to the second aspect of the present invention.

[0013] According to a fourth aspect of the present invention, there is provided a remote digital slit lamp (RDSL) comprising a slit height adjustment mechanism according to the first aspect of the present invention and / or a slit width adjustment mechanism according to the second aspect of the present invention, and / or a light conditioning apparatus according to the third aspect of the present invention.

[0014] Provision of such a slit height adjustment mechanism, slit width adjustment mechanism, light conditioning apparatus and RDSL according to the first, second, third and fourth aspects of the present invention enables the RDSL to have the full functionality of a non-remote, analogue (i.e. traditional) slit lamp.

[0015] The drive means of the slit height adjustment mechanism (SHAM) and / or slit width adjustment mechanism (SWAM) may comprise a stepper motor. Preferably, the SHAM and SWAM each comprise a dedicated stepper motor. Use of a stepper motor provides enhanced control capabilities when compared with linear motors.

[0016] The or each stepper motor may be operable to selectively turn a full step, half step, step, 1 / 8 step, 1 / 16 step, 1 / 32 step, 1 / 64 step, 1 / 128 step and 1 / 256 step (referred to as a “micro step”).

[0017] The or each stepper motor may be operable to rotate with different speeds. The rotation speed may be dependent upon the frequency of the step pulsation. The rotation speed may be measured in round per seconds (RPS). The or each stepper motor may be operable between 0.1 and 50 RPS. The minimum and maximum RPS of the or each stepper motor may be 0.5 and 20 RPS respectively. Preferably, the minimum and maximum RPS of the or each stepper motor are 1 and 10 RPS respectively. Accordingly, for the preferred embodiment, 1%, 10%, 50% and 100% speeds correspond to 1.09, 1.9, 5.5 and 10 RPS respectively.

[0018] The or each stepper motor may be operable in response to control signals sent from a control unit. The filter plate of the SHAM may be circular. The filter plate may be connected to the drive means at its centre, such that it can rotate in place. The defined movement path of the filter plate may be rotation about the centre of the filter plate. In these embodiments, the filter plate may be circular.

[0019] In such embodiments, the aperture in the filter plate having a dimension along the secondary axis varying along the length of the primary axis (referred to as “the principal aperture”) may be in the form of an arcuate tear drop. In such embodiments, the principal aperture may extend from a point to a round semi-circle at the opposite end of the principal aperture. The semi-circle may have a radius of 7mm. The principal aperture may sweep through an angle of 144°.

[0020] The filter plate may be between 1 and 5mm thick. In one embodiment, the filter plate is about 2mm thick.

[0021] In embodiments where the filter plate is circular, it may have a radius of between 30 and 60mm. In one embodiment, the filter plate has a radius between 40 and 50mm. In one embodiment, the filter plate has a radius of about 43mm.

[0022] Alternatively, the filter plate may be an elongate rectangle. In such embodiments, the defined movement path of the filter plate may be bi-directional liner motion along the long-axis filter plate.

[0023] The filter plate may comprise one or more apertures in addition to the principal aperture. The filter plate may comprise an aperture comprising a blue light filter. The filter plate may comprise a square aperture having 1mm side length. The filter plate may comprise a circular aperture having 10mm diameter.

[0024] The SHAM may comprise a limit switch operable to limit the motion of the filter plate. The limit switch may be an optical limit switch. The filter plate may comprise a cut-out operable to trigger the optical limit switch once the cut out reaches the optical limit switch. In such embodiments, the optical limit switch may comprise an emitter and receiver placed in opposing positions either side of the filter plate, the optical limit switch being configured to allow movement of the filter plate when the receiver does not receive light from the emitter and prevents movement when the receiver receives light from the emitter (i.e. when the cut-out reaches the position of the optical limit switch).

[0025] The slit plates of the SWAM may each be conventional.

[0026] The cam of the SWAM may be circular. In such embodiments, the cam may be connected to the drive means at its centre, such that it can rotate in place. The cam may have a diameter between 20 and 50mm. In one embodiment, the cam has a diameter between 30 and 40mm. In one embodiment, the cam has a diameter of about 36mm.

[0027] The cam may comprise a limit switch operable to limit the motion of the cam. The limit switch may be an optical limit switch. The cam may comprise one or more cut-out operable to trigger the optical limit switch once a cut out reaches the optical limit switch. In such embodiments, the optical limit switch may comprise an emitter and receiver placed in opposing positions either side of the cam, the optical limit switch being configured to allow movement of the cam when the receiver does not receive light from the emitter and prevents movement when the receiver receives light from the emitter (i.e. when the cut-out reaches the position of the optical limit switch).

[0028] The or each cut out may comprise a radial slit extending from the perimeter toward the centre of the cam. In a particular embodiment, there may be four evenly spaced radial slits each arranged at approximately 90 degrees to the adjacent slits. As will be understood by the skilled person, the rotation of the cam is translated into linear motion of the followers, and so the limit switch of the cam are operable to limit motion of the followers (and slit plates) accordingly.

[0029] Provision of such limit switches within the cam also enables better calibration of the devices, as the relative position of the cam and slit plates can be more easily determined .

[0030] The abutting members may each protrude from the cam in an axial direction. The abutting member may each protrude a distance of between 10 and 20mm from the cam. The abutting members may be placed between 10 and 20mm from each other. Each abutting member of the cam may be surface coated to ensure the followers smoothly follow the motion of the cam. Each abutting member may protrude a different distance from the cam. Each abutting member may comprise a bearing placed at the end of the abutting member distal from the cam.

[0031] It will be understood that any specific dimensions given above are simply reflective of the specific embodiments to which they relate, and that the skilled person would understand that different dimensions could be used to achieve the same result.

[0032] The followers may each comprise an abutment surface. The abutment surfaces of the followers may be arranged such that they face each other. Each abutment surface may be surface coated to ensure the followers smoothly follow the motion of the cam.

[0033] In a specific embodiment, each abutment surface may be an aperture formed in the relevant follower. In such embodiments, each such aperture may be arranged so as to receive an abutting member. Each follower may comprise a protruding region in which the aperture is formed. Each protruding region may extend towards the other opposite follower so as to extend above and receive an abutting member of the cam. Each aperture may be in the form of a slot in which an abutting member is received. The slot may be curved so as to allow more precise control of the distance between the followers (and hence the pair of slit plates).

[0034] In embodiments where the abutting members protrude different distances from the cam, the protruding regions (where present) of the followers may be offset in terms of their relative heights. This allows the apertures in said protruding regions to match the heights of the corresponding abutting member, and for each aperture to receive an abutting member. The offsetting of the abutting members and apertures helps to prevent movement interference which can arise where the protruding members are the same height.

[0035] The followers may each be biased towards one another. The followers may be each be biased away from external structure. Alternatively, the followers may be biased towards each other via one or more shared biasing members.

[0036] In such embodiments, the or each shared biasing member may be in the form of one or more helical springs attached to each follower. The skilled person will understand that many types of biasing member are suitable. The shim may be placed in line with the centre of the cam. The shim may be placed equidistant between the slit plates of the SWAM. The shim may have a width between 0.1 and 0.2mm. In one embodiment, the shim has a width of about 0.1mm.

[0037] The SWAM may comprise a limit switch operable to limit the motion of the cam, and hence the followers and slit plates. The limit switch may be an optical limit switch. The cam may comprise a cut-out operable to trigger the optical limit switch once the cut out reaches the optical limit switch. In such embodiments, the optical limit switch may comprise an emitter and receiver placed in opposing positions either side of one of the cam, the optical limit switch being configured to allow movement of the plate when the receiver does not receive light from the emitter, and prevents movement when the receiver receives light from the emitter (i.e. when the cam has moved a distance such that the cut-out reaches the position of the optical limit switch).

[0038] The RDSL may comprise a light source. The light source may comprise a halogen bulb. Alternatively, the light source may be one or more LEDs arranged in an LED module.

[0039] The light source may have a temperature between 2000K and 3500K. Preferably, the light source has a temperature between 2500K and 3000K. Most preferably, the light source has a temperature of about 2700K.

[0040] The light source may have a Colour Rendering Index (CRI) of at least 80. Preferably, the CRI of the light source is at least 90.

[0041] The light source may be positioned adjacent to the SHAM such that the light beam emitted by the light source passes through an aperture within the filter plate of the SHAM (when said aperture is aligned with the light source). In this manner, moving the filter plate can therefore adjust the dimensions or colour of the light beam. In particular, when the light beam is shone through the principal aperture, the height of the light beam can be adjusted by moving the filter plate via the drive means.

[0042] The light source may be positioned adjacent to the SWAM such that the light beam emitted by the light source passes between the slit plates of the SWAM. In this manner, moving the cam and hence followers and slit plates can therefore adjust the width of the light beam. The filter plate of the SHAM and slit plates of the SWAM may be in close proximity to each other. This can help ensure that that the light beam passing through (and being modified by) the SHAM and SWAM is in focus at the plane of the patient’s eye.

[0043] The RDSL may comprise a communication unit operable to transmit and receive information to / from an external control apparatus. The communication unit may be operably connected to the control unit of the RDSL. The external control apparatus may comprise user control interface. This allows a user to input control commands to the external control apparatus, and thereby control the RDSL and perform an eye examination remotely.

[0044] The external control apparatus may comprise a communication unit to transmit and receive information to / from the communication unit of the RDSL. The transmitted information may comprise control signals corresponding to the control commands inputted to the user control interface.

[0045] The RDSL may comprise a control unit operable in response to the control signals received from the external control apparatus.

[0046] The control unit of the RDSL may be operable to control the or each stepper motor of the RDSL.

[0047] The RDSL may comprise one or more cameras operable to capture images and / or video of the patient’s eye. The RDSL is thus operable to capture images and / or video of any test performed on the patient’s eye.

[0048] The control unit may be operable to initiate imaging and or video recording using the one or more cameras. The control unit may be operable to initiate imaging and or video recording in response to the control signals received from the external control apparatus.

[0049] The control unit may be operable to transmit any captured images and / or videos to the external control apparatus via the communication unit. The control unit may be operable to store any captured images and / or videos to a storage unit. The storage unit may comprise a local storage device. The storage unit may comprise an external storage unit. The storage unit may be cloud-based.

[0050] The control unit may be operable to automate any and / or all of the functions of the RDSL. This allows for the examination of the patient’s eye to be performed without operator supervision.

[0051] The remote digital slit lamp may comprise conventional controls, to allow the slit lamp to be operated in person by an operator. This allows maximal flexibility by allowing the remote digital slit lamp to be used remotely or in-person.

[0052] The light conditioning apparatus and RDSL of the third and fourth aspects of the present invention may be provided with any of the optional features of the SHAM and SWAM of the first and second aspects of the present invention as desired or as required.

[0053] According to a fifth aspect of the present invention there is provided a method of examining an eye using a remote digital slit lamp according to the fourth aspect of the present invention.

[0054] The method may comprise the storing of all captured images. This allows an ophthalmologist and / or optician to review the captured images after the examination has ended.

[0055] The method may comprise an operator controlling the RDSL from a remote location. Alternatively, the method may comprise the RDSL automatically performing one or more steps of the eye examination without being remote controlled. The method may comprise the RDSL being controlled by an operator in person to perform one or more steps of the eye examination.

[0056] The method may involve performing one or more of the following eye examinations: a direct diffuse illumination examination, an optic section and corneal sweep examination, an indirect illumination examination, retro-illumination examination, a sclerotic scanner examination, a specular reflection examination, a Van Herick’s examination, a palpebral conjunctiva examination, a fluorescein examination, a red-free filter examination and a posterior chamber examination using a fundus lens. Detailed Description of the Invention

[0057] In order that the invention may be more clearly understood one or more embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, of which:

[0058] Figure 1 shows a perspective view of a remote digital slit lamp.

[0059] Figure 2 shows a perspective view of the light conditioning apparatus of a remote digital slit lamp having a slit height adjustment mechanism and a slit width adjustment mechanism.

[0060] Figure 3 shows a view of a slit height adjustment mechanism.

[0061] Figure 4 shows a view of a slit width adjustment mechanism.

[0062] Figure 5 shows a control apparatus for a remote digital slit lamp.

[0063] Turning to figure 1, there is provided a remote digital slit lamp (RDSL) 1. The RDSL 1 has a chin rest 2 and forehead rest 3, such that a patient (not shown) placing their chin and forehead onto the respective chin and forehead rests 2, 3 has their eye / s substantially level with an eye examination apparatus 4. The RDSL 1 also has traditional control and feedback unit 5, allowing the RDSL 1 to be used by an operator (not shown) in person, as opposed to being strictly remote controlled.

[0064] The RDSL has a conventional optics arrangement, in that the RDSL has components which each provide the same function as a conventional (i.e., non-remote, analogue) slit lamp. The optics arrangement includes a light source (in the case of the exemplary embodiment described below, this is an LED light source), a condensing lens system to focus the parallel beam of light emitted by the light source, Slit Width and Slit Height adjustment mechanisms (as discussed in more detail below) and one or more filters to adjust the properties of the light.

[0065] Figure 2 shows a light conditioning apparatus 11 of the RDSL 1. The light conditioning apparatus 11 has a vertical frame 12, at the bottom of which is an LED module 13 arranged to emit light upwards through the vertical frame 12. The vertical frame 12 is square in cross section and has a conventional lens holder 14 at its top. The vertical frame 12, LED module 13 and lens holder 14 are arranged such that light emitted from the LED module 13 is received by the lens holder 14 at the opposite end of the vertical frame 12.

[0066] Placed between the LED module 13 and the lens holder 14, there is a slit height adjustment mechanism (SHAM) 20 and a slit width adjustment mechanism (SWAM) 40. The SHAM 20 and SWAM 40 are each supported by the vertical frame 12 and are arranged such that the light from the LED module 13 passes through both the SHAM

[0067] 20 and SWAM 40 before it reaches the lens holder 14. In this embodiment, the SWAM 40 is placed adjacent to the LED module 14, and the SHAM 20 is placed above the SWAM 30 (i.e. closer to the lens holder 14). It will be understood that the positions of the SHAM 20 and SWAM 40 could be reversed if desired.

[0068] Turning to figure 3, there is shown the SHAM 20, when viewed from below (i.e. as viewed from the LED module 13 and SWAM 40). The SHAM 20 has a circular filter plate 21 connected to a stepper motor 22 (shown in Figure 2) at its centre, such that the circular filter plate 21 rotates about its centre in response to the stepper motor 22. The circular filter plate 21 is suspended from the stepper motor 22, such that it hangs freely.

[0069] The stepper motor 22 is fixedly attached to a support plate 23, which itself fixedly attached to the vertical frame 12. The circular filter plate 21 thus hangs below the support plate 23. This allows the stepper motor 22 to rotate the circular filter plate

[0070] 21 in relation to the light conditioning apparatus 11 of the RDSL 1. The support plate 23 has an aperture 24 which is arranged such that it does not block the light emitted from the LED module 13 from reaching the lens holder 14.

[0071] The circular filter plate 21 comprises five apertures 25-29. The apertures 25-29 are arranged on the circular plate 20 in a circle sharing a centre with that of the plate itself. In other words, the centres of each aperture 25-29 are equidistant from the centre of the circular filter plate 21.

[0072] The vertical frame 11, support plate 23, stepper motor 22, and circular filter plate 21 are each arranged such that, when one of the apertures 25-29 is aligned with the aperture 24 in the support plate, the light emitted from the LED module 13 is not prevented from reaching the lens holder 14. The apertures 25-29 are each sized, shaped and / or otherwise arranged so as to modify the properties of the light passing through the aperture 25-29. The principal aperture 25 is in the shape of an arcuate teardrop, which spans approximately 40% of the circumference of the circular filter plate 21. The principal aperture 25 is arranged such that the principal aperture 25 decreases in size from one end of the principal aperture 25 to the other. In this manner, the height of the light beam passing through the principal aperture 25 can be adjusted through movement of the circular filter plate 21 (which is achieved through the stepper motor 22).

[0073] The other apertures 26-29 present in the circular filter plate 21 each modify the light beam in accordance with their properties. One aperture 26 has a blue light filter across the aperture, to remove wavelengths of light below 465nm and above 490nm ± 3nm. This enables the RDSL 1 to perform fluorescein imaging.

[0074] A different aperture 27 is circular and has a diameter of 10mm. Another aperture 28 is circular and has a diameter of 0.3mm. The final aperture 29 is square and has a side length of 1mm. These apertures 27, 28, 29 enable the RDSL to perform all standard eye examination techniques that a conventional manual, slit lamp can perform.

[0075] A conventional optical limit switch 30 is attached to the support plate 23. The optical limit switch 30 extends downwards from the support plate 23, and has the form of a C- shape, where the outer edge of the circular filter plate 21 is received within the recess of the C-shape. Along the outer edge of the circular plate there is rectangular cutout 31 which extends toward the centre of the circular filter plate 21. In normal use, the light beam within the optical limit switch 30 is broken by the circular filter plate 21. However, when the circular filter plate 21 reaches its maximal rotation, the cut-out 31 reaches the optical limit switch 30, and the light beam within the optical limit switch 30 is no longer broken. The optical limit switch 30 can then send appropriate signals to the stepper motor 22 and / or the control apparatus (not shown). This enables the calibration of the stepper motor 22, and also prevents over-rotation of the circular filter plate 21.

[0076] Turning to figure 4, the SWAM 40 is shown from above. The SWAM 40 comprises a cam 41, which is rotatably mounted to a stepper motor 42 (shown in Figure 2) at its centre, such that the cam 41 rotates about its centre in response to the stepper motor 42. The stepper motor 42 is fixedly attached to a support structure 43, which is itself fixedly attached to the vertical frame 12 of the RDSL. This allows the stepper motor 42 to rotate the cam 41 in relation to the light conditioning apparatus 11 of the RDSL 1. The support structure 43 which is arranged such that it does not block the light emitted from the LED module 13 from reaching the lens holder 14.

[0077] The cam 41 comprises a pair of abutting members 44,45, which each extend perpendicularly away the cam 41. The members 44,45 each extend vertically upwards (i.e. away from the stepper motor 42). The members 44,45 are placed on the cam diametrically opposite to one another.

[0078] A pair of followers 46,47 are positioned either side of the cam 41, such that the followers 46,47 are able to abut the abutting members 44,45 of the cam 41. Each follower 46,47 abuts a single member 44,45 at an abutment surface 48,49.

[0079] The followers 46,47 are each cuboidal, elongate and extend from a position adjacent the cam 41 and abutting members 44,45 to a free end within the confines of the vertical frame 12, adjacent the light beam emitted by the LED module 13.

[0080] The followers 46,47 are biased towards each other by a pair of helical springs

[0081] 50 attached to each follower 46, 47. This forces the abutment surfaces 48,49 of the followers 46,47 to abut the members 44,45 of the cam 41. In this manner, the followers 46,47 can ‘follow’ the motion of the abutting members 44,45 which is defined by the motion of the cam 41 (driven by the stepper motor 42).

[0082] At their free ends, each follower 46,47 comprises a slit plate 51. The slit plates

[0083] 51 face each other, and partially occlude the light beam emitted from the LED module 13 which passes upwards through the vertical frame 12. In this manner, the width of the light beam can be modified, as the slit plates 51 can be moved with the followers 46,47 in response to rotation of the cam 41.

[0084] The slit plates 51 are flat and free from imperfections in line with convention, in order to produce a suitably well-defined light beam.

[0085] Between the slit plates 51, there is placed a shim 52. The shim 52 is mounted to the support structure 43 of the SWAM 40 at the opposite end to the cam 41 and extends between the slit plates 51. The shim 52 defines a minimum slit width between the slit plates 51. In this embodiment, the shim 52 is 0.1mm wide, so as to define a 0.1mm minimum slit width, which is required for the RDSL 1 to function fully.

[0086] The SWAM 40 is provided with an optical limit switch 53. The optical limit switch 53 is conventional, and functions in the same manner as the optical limit switch 30 of the SHAM 20.

[0087] Turning to figure 5, there is shown a control apparatus 101 for the RDSL 1. The control apparatus 101 comprises a central processing unit 102, which is operably connected to the stepper motors 22,42 and optical limits switches 30,53 of both the SHAM 20 and SWAM 40. The central processing unit 102 is operable to control the motion of each stepper motor 22,42, either in response to control signals input by a user, in line with automated control signals in line with pre-programmed functions, or in response to the signals received from the relevant optical limit switch 30,53.

[0088] In this manner, the control apparatus 101 is able to adjust the properties of the light beam produced by the RDSL 1, so as to perform a variety of eye examination techniques as required.

[0089] The control apparatus 101 is operably connected to a camera 103, which is operable to record both images and video of the patient’s eye which being examined by the RDSL 1. The central processing unit 102 is operably connected to a communication unit 104. The central processing unit 102 is operable to store the image / s and / or video / s recorded by the camera 103 to a suitable storage unit 105. In addition, the central processing unit 102 is operable, via the communication unit 104, to transmit the image / s and / or video / s recorded by the camera 103 to an external storage medium 107 (for example cloud-based storage).

[0090] The control apparatus 101 also comprises conventional controls 106, to allow the RDSL 1 to be operated in person, if required. The conventional controls 106 transmit control signals to the central processing unit 102 in response to user inputs, and the central processing unit 102 controls the RDSL 1 accordingly.

[0091] The communication unit 104 is operable to transmit and receive data from a corresponding communication unit 114 of an external control apparatus 111. The external control apparatus 111 comprises its own central processing unit 112, and a user interface 113. The user interface 113 is operable to display information regarding the state of the RDSL 1. In some embodiments, the user interface 113 is also operable to receive user control inputs. In such embodiments, the central processing unit 112 of the external control apparatus 111 is operable, via the communication 114, to transmit the user control inputs to the control apparatus 101 of the RDSL 1 , which is then controlled according to the user control inputs.

[0092] In other embodiments, the user interface 113 may be in the form of a dedicated display 113a and dedicated user input 113b.

[0093] The one or more embodiments are described above by way of example only. Many variations are possible without departing from the scope of protection afforded by the appended claims.

Claims

CLAIMS1. A slit height adjustment mechanism for use in a remote digital slit lamp (RDSL), the slit height adjustment mechanism comprising: a drive means, a filter plate movable along at least one defined movement path by the drive means; an aperture in the filter plate having a primary axis aligned with the movement path of the filter plate and a secondary axis, transverse to the primary axis defining slit height; wherein the dimension of the aperture along the secondary axis varies along the length of the primary axis, such that moving the filter plate along the movement path enables the height of a light beam shone through the aperture to be adjusted.

2. A slit height adjustment mechanism according to claim 1 wherein the drive means comprises a stepper motor.

3. A slit height adjustment mechanism according to either claim 1 or 2 wherein the filter plate is circular.

4. A slit height adjustment mechanism according to claim 3 wherein the filter plate is connected to the drive means at its centre, such that it can rotate in place.

5. A slit height adjustment mechanism according to claim 4 wherein the defined movement path of the filter plate may be rotation about the centre of the filter plate.

6. A slit height adjustment mechanism according to any of claims 3 to claim 5 wherein the aperture in the filter plate having a dimension along the secondary axis varying along the length of the primary axis (the principal aperture) is in the form of an arcuate tear drop.

7. A slit height adjustment mechanism according to claim 6 wherein the filter plate comprises one or more apertures in addition to the principal aperture.

8. A slit height adjustment mechanism according to any preceding claim comprising a limit switch operable to limit the motion of the filter plate.

9. A slit width adjustment mechanism for use in a remote digital slit lamp (RDSL), the slit width adjustment mechanism comprising:a pair of slit plates defining a slit therebetween, a drive means, a cam connected to the drive means, the cam comprising a pair of abutting members arranged diametrically opposite to each other, a pair of followers each biased toward the centre of the cam, each follower being arranged to abut one of the abutting members of the cam so as to follow the movement of the corresponding abutting member, each follower comprising one of the slit plates, and characterised in that a shim is placed between the slit plates to define a minimum slit width.

10. A slit width adjustment mechanism according to claim 9 wherein the drive means comprises a stepper motor.

11. A slit width adjustment mechanism according to either claim 9 or 10 wherein the cam of the slit width adjustment mechanism is circular.

12. A slit width adjustment mechanism according to claim 11 wherein the cam is connected to the drive means at its centre, such that it can rotate in place.

13. A slit width adjustment mechanism according to any of claims 9 to 12 wherein the followers are biased towards each other via one or more shared biasing members.

14. A slit width adjustment mechanism according to any of claims 9 to 13 wherein the shim is placed in line with the centre of the cam.

15. A slit width adjustment mechanism according to any of claims 9 to 14 wherein the shim is placed equidistant between the slit plates of the slit width adjustment mechanism.

16. A slit width adjustment mechanism according to any of claims 9 to 15 wherein the shim has a width of 0.1mm.

17. A slit width adjustment mechanism according to any of claims 9 to 16 comprising a limit switch operable to limit the motion of the cam, and hence the followers and slit plates.

18. A light conditioning apparatus for use in a remote digital slit lamp (RDSL) comprising a slit height adjustment mechanism according to any of claims 1 to 8 and / or a slit width adjustment mechanism according to any of claims 9-17.

19. A remote digital slit lamp (RDSL) comprising any of the following: a slit height adjustment mechanism according to any of claims 1 to 8; a slit width adjustment mechanism according to any of claim 9 to 17; a light conditioning apparatus according to claim 18.

20. A RDSL according to claim 19 comprising a light source.

21. A RDSL according to claim 20 wherein the light source is one or more LEDs arranged in an LED module.

22. A RDSL as claimed in any of claims 19-21 comprising one or more cameras operable to capture images and / or video of a patient’s eye.

23. A RDSL as claimed in any of claims 19-22 comprising a control unit operable to automate any and / or all of the functions of the RDSL.

24. A RDSL as claimed in any of claims 19-23 comprising conventional controls, to allow the slit lamp to be operated in person by an operator.

25. A method of examining an eye using a remote digital slit lamp according to any of claims 19-24.

Images