WO2023279172A1

WO2023279172A1 - Method, device and system for combining scleral and corneal topography data

Info

Publication number: WO2023279172A1
Application number: PCT/AU2022/050721
Authority: WO
Inventors: Paul LICHTENAUER; Robert HEAVYSIDE
Original assignee: Medmont International Pty Ltd
Priority date: 2021-07-09
Filing date: 2022-07-08
Publication date: 2023-01-12

Abstract

A method for combining scleral and corneal topography data is disclosed. The method comprises registering the scleral data and the corneal data using corneal height data and one or more corneal reference comprised in the corneal data and using a scleral registration reference comprised in the scleral data. Also disclosed is a device, ophthalmological topographer and system for obtaining combined scleral and corneal topography data. The registration may use a coordinate system.

Description

METHOD. DEVICE AND SYSTEM FOR COMBINING SCLERAL AND CORNEAL TOPOGRAPHY DATA

FIELD OF THE INVENTION

[0001] The present invention relates to a method, device and system for combining scleral and corneal topography data. More particularly this invention relates to a method, device and system for combining scleral and corneal topography data wherein scleral data obtained from projection based topography and corneal data obtained from reflection based topography are registered using corneal height data to one or more corneal reference and a scleral registration reference.

BACKGROUND TO THE INVENTION

[0002] Corneal topographers measure the geometry of the anterior corneal surface. It is well known, and desired, in the ophthalmic industry, that scleral height data is advantageous for use of fitting contact lenses that are located on the sclera instead of the cornea. For cases where the corneal shape is complex, for instance through the presence of a keratoconic cornea, fitting over the cornea may not achieve the desired effects and worse still, may cause complications. Whereas, seating the contact lens entirely over the cornea and contacting on the sclera shows improved patient comfort and stability.

[0003] Scheimpflug topography and other projection type topographic systems and lately OCT (optical coherence tomography) has been applied to corneal and scleral mapping to map the entire ocular anterior surface. With the Scheimpflug method, the high intensity light used for the retina typically results in the sclera becoming blurred. Further disadvantages of Scheimpflug systems are the high cost of instruments and long capture time, which results in loss of accuracy and thereby requires complex registration methods. [0004] Another method is to use sodium fluoride (fluorescein) on the surface of the eye to make the whole anterior surface partially opaque. This allows a pattern to be projected onto the whole anterior surface and processed into height information.

[0005] Alternative and improved methods, devices and systems for combining scleral and corneal topography data are desirable.

[0006] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge. SUMMARY OF THE INVENTION

[0007] The present invention is directed to a method, device and system for combining scleral and corneal topography data. Advantageously, this may allow the representation of the anterior surface of the eye as a single object.

[0008] In one broad form, the invention is directed to a method, device and system for combining scleral and corneal topography data wherein scleral data obtained from projection based topography and corneal data obtained from reflection based topography are registered by using corneal height data to one or more corneal reference and a scleral registration reference.

[0009] In another broad form, the invention relates to a combined scleral and corneal image obtained by combining projection based scleral topography data and reflection based corneal topography data and registering the scleral topography data with the corneal topography data using corneal height data to one or more corneal reference and a scleral registration reference.

[0010] In a first aspect, although it need not be the only or indeed the broadest form, the invention provides a method for combining scleral and corneal topography data, the method comprising: receiving scleral data obtained from projection based topography and corneal data obtained from reflection based topography; and registering the scleral data and the corneal data using corneal height data and one or more corneal reference comprised in the corneal data and using a scleral registration reference comprised in the scleral data.

[0011] In a second aspect, the invention provides a device for combining scleral and corneal topography data, the device comprising: one or more processor for registering the scleral data and the corneal data using corneal height data and one or more corneal reference comprised in the corneal data and using a scleral registration reference comprised in the scleral data.

[0012] In a third aspect, the invention provides an ophthalmological topographer comprising: a projection based topographer comprising a reference object; a topography illumination source illuminating the reference object; and an imaging system imaging the reference object projected onto said eye surface through a central channel in the light guide body to generate corneal data; a scleral measurement device comprising one or more scleral projection systems, each of the one or more scleral projection systems comprising a scleral projection light source and a scleral reference object to generate scleral data; and one or more processor to register the scleral data and the corneal data using corneal height data and one or more corneal reference comprised in the corneal data and using a scleral registration reference comprised in the scleral data.

[0013] In a fourth aspect, the invention provides a system for combining scleral and corneal topography data, the system comprising: one or more processor for receiving scleral data obtained from projection based topography and corneal data obtained from reflection based topography; one or more processor for registering the scleral data and the corneal data using corneal height data and one or more corneal reference comprised in the corneal data and using a scleral registration reference comprised in the scleral data.

[0014] According to any one of the first to fourth aspects, the invention may further comprise: constructing and/or displaying a combined image from the registered scleral data and the registered corneal data.

[0015] According to any one of the first to fourth aspects, one or more display for displaying the combined image may be further comprised.

[0016] In a fifth aspect, the invention provides a combined scleral and corneal image obtained by combining projection based scleral topography data and reflection based corneal topography data registering the scleral data and the corneal data using corneal height data and one or more corneal reference comprised in the corneal data and using a scleral registration reference comprised in the scleral data.

[0017] According to any one of the above aspects, registration uses a reference frame. The reference frame may comprise a coordinate system such as, an orthogonal coordinate system or a polar coordinate system. The registration may utilize x,y,z data. The corneal data may be referenced to eye apex. Registration may utilize a height reference comprised in the corneal data.

[0018] According to any one of the above aspects, registration uses scleral location relative to a capture device reference and a scleral registration reference. The scleral registration reference may coincide with a corneal position and wherein the scleral data and corneal data are captured independently. The scleral registration reference may be located on the cornea. The capture device reference may be to coordinates to an instrument calibration by lens position. The scleral reference may contain corneal information regarding position and rotation and is comprised in the scleral data.

[0019] The method of the first aspect may further comprise the step of calculating a scleral image axis for the scleral data and calculating a corneal image axis for the corneal data.

[0020] According to the second or third aspect, the invention may further comprise one or more processor for calculating a scleral image axis for the scleral data and calculating a corneal image axis for the corneal data.

[0021] According to any one of the above aspects, the invention further provides: displaying the combined image on a visual display.

[0022] According to any one of the above aspects, the scleral data comprise a different resolution to a resolution of the corneal data. In a particular embodiment, the comeal data may comprise a higher resolution than the scleral data.

[0023] According to any one of the above aspects the scleral height data may be obtained at a resolution of 1 to 10 pm. The resolution may be 1; 2; 3; 4; 5; 6; 7; 8; 9 or 10 pm. The scleral data may comprise a scleral coverage from 11.5 mm diameter to 20 mm diameter. The scleral height data may be up to 6mm. The scleral height may be measured from the corneal apex. The scleral height may be the range for measurements to 20 mm coverage of said eye in an x,y diameter.

[0024] According to any one of the above aspects, three dimensional (3D) scleral height data may be calculated from the scleral data from x,y,z coordinates of scleral locations of and the instrument parameters of a calibrated capture device. The scleral height data may be relative to a capture device reference.

[0025] According to any one of the above aspects, one or both of the scleral data and the corneal data are obtained aligned to an eye reference axis. The scleral height data and the corneal height data may be orthogonal or substantially orthogonal. In other embodiments, the scleral data is obtained not aligned with an eye reference axis.

[0026] According to any one of the above aspects, the axis calculated is an eye reference axis. The eye reference axis may be the videokeratoscope (VK) axis or the apex of the optical axis.

[0027] According to any one of the above aspects, the corneal data comprise corneal height data of the anterior eye surface. The corneal height data may comprise data obtained a resolution of 1 to 2 pm. The corneal data may comprise a corneal coverage from 8 to 11 mm or from 8 mm to an edge of the limbus. The corneal data may further comprise corneal reference data. The corneal reference data may comprise a corneal coordinate data set. The corneal height data may be obtained from a reflection image of said eye. The corneal height data may comprise a coverage of 11 mm diameter. The corneal height data may comprise a height of typically 2 to 2.5mm at the coverage.

[0028] According to any one of the above aspects, the registration may comprise x,y,z translation to a corneal reference. The translation may result in the combined corneal and scleral height data referenced to a corneal reference.

[0029] According to any one of the above aspects, the registration may also comprise angular rotation. The angular rotation may be of the scleral height data relative to the coordinate system. The angular rotation may comprise one, two, three or three or more angular rotations. The registration may utilise a reference comprised in the corneal data such as the corneal reference object. After registration the scleral data and corneal data may be combined in composite data which may be associated with an eye reference such as, the eye apex. The registration may be to any eye reference axis, such as, an optical axis or a visual axis.

[0030] According to any one of the above aspects, the registration uses (i) x and y location relative to a capture device reference comprised in the scleral data.

[0031] According to any one of the above aspects, the registration uses (ii) information on the eye reference axis location relative to a capture device instrument reference comprised in the corneal data.

[0032] According to any one of the above aspects, a further processing may improves accuracy for smaller reference deviations above 0.5 deg from the eye references axis, and optionally, enable combining corneal and scleral height data for larger differences, such as 1 deg up to 20 deg of the eye reference axis between the images.

[0033] According to any one of the above aspects, the ophthalmological topographer comprises: a corneal topographer comprising a reference object; a topography illumination source illuminating the reference object; and an imaging system imaging the reference object projected onto said eye surface through a central channel in the light guide body.

[0034] According to any one of the above aspects, the invention provides an ophthalmological topographer comprising: a directing optical system housed in a proximal end of the light guide body directing light from the corneal topographer across said corneal profile; and a reflecting optical system housed in the proximal end of the corneal topographer reflecting light from the directing optical system that has traversed the corneal profile through the light guide body.

[0035] The imaging system according to any one of the above aspects may comprise one or more lens. The imaging system may direct light onto one or more capture system.

[0036] The reflecting optical system according to any one of the above aspects may reflect light for capture on the at least one imaging sensor.

[0037] According to any one of the above aspects, one or more capture system may be comprised. The one or more capture system may comprise at least one imaging sensor such as a CCD (charge-coupled device) or CMOS (complementary metal-oxide-semiconductor (CMOS) image sensor. The one or more capture system may comprise a topography capture system and a profile capture system. The topography capture system may be used in topography utilising the reference object. The profile capture system may be used in eye profiling utilising light directed by the reflecting optical system. In another embodiment the one or more capture system comprises at least one imaging sensor for both topography and eye profiling.

[0038] In one embodiment of any one of the above aspects, the topographer comprises a lighting array comprising a topography illumination source and a profile optics illumination source. The topographer illumination source may comprise a distributed light source. The distributed light source and the profile optics illumination source may be resolvable or distinguishable. The distributed light source and profile optics illumination source may emit light at sufficiently different wavelengths so no interference in their corresponding imaging paths occurs.

[0039] The distributed light source may comprise a plurality of LEDs. The distributed light source may emit a broadband visible spectrum. Each of the plurality of LEDs may comprise an RGB LED. Each RGB LED may comprise an individual narrow waveband. Each of the plurality of LEDs may produce white light. The plurality of LEDs may comprise an array arranged in a particular embodiment as two or more rings of LEDs. The two or more rings of LEDs may be comprised on a printed circuit board.

[0040] The profile optics illumination source may emit infra-red light. The profile optics illumination light source may comprise a point light source. In one embodiment, the profile optics illumination light source is a LED. [0041] In yet another embodiment of any one of the above aspects, a portion of an optical path of the distributed light source, and a portion of an optical path of the profile optics illumination source illuminates said eye surface.

[0042] The topography illumination source and/or profile optics illumination source may be disposed at a distal end of the light guide body.

[0043] In one embodiment of any one of the above aspects, the reference object comprises a plurality of annuli. The reference object may comprise a Placido disk comprising a plurality of concentric annuli. The plurality of concentric annuli may comprise alternating transparent and opaque annuli. The transparent annuli may be illuminated. The transparent annuli may be integral with the light guide body. The concentric annuli may be disposed along a length of an interior surface of the light guide body. The reference object may comprise an overlay comprising opaque annuli. The opaque annuli may be arranged linearly separated by transparent sections. The reference object may be painted or otherwise disposed on the light guide body. The painting or other application may comprise application of only the opaque annuli.

[0044] In another embodiment of any one of the above aspects, the light guide body comprises a substantially conical or toric shape. The substantially conical shape may comprise a frusto-conical shape. The conical or toric shape may comprise an internal channel. The external surface may comprise a curved or toric shape and the internal channel may comprise a substantially conical shape.

[0045] In yet another embodiment of any one of the above aspects, the directing optical system and the reflecting system are positioned on substantially opposing points of the light guide body.

[0046] The directing optical system may comprise one or more prism disposed between the light source and exposed eye. The prism may comprise a diffusing prism.

[0047] The reflecting optical system may comprise one or more mirrors.

[0048] In another embodiment the directing optical system may comprise a mirror and the reflecting optical system may comprise a prism.

[0049] In yet another embodiment of any one of the above aspects, light targeted by the reflecting optical system is incident on a profile imaging system disposed at a distal end of the light guide body.

[0050] In another embodiment of any one of the above aspects, the profile imaging system comprises one or more of a focusing lens system and an optical filter only transmitting light from the profile optics illumination source. [0051] In yet another embodiment of any one of the above aspects, the profile imaging system focuses the targeted light onto the one or more capture system. The focused targeted light comprises information on the distance of the subject eye from a reference point.

[0052] In still another embodiment of any one of the above aspects, the profile imaging system focuses the profile plane of said eye onto the one or more capture system.

[0053] According to any one of the above embodiments, the reflecting optical system and the directing optical system for imaging the eye profile are comprised in a profile system. [0054] According to any one of the above aspects, the ophthalmological topographer may comprise a corneal topographer. According to this embodiment the eye surface comprises the corneal surface; the eye profile comprises the corneal profile; the illumination of the eye may comprise illumination of the cornea; and the eye coverage may comprise corneal coverage.

[0055] According to any one of the above aspects, the topographer may further comprise a scleral measurement device. The scleral measurement device may comprise one or more scleral projection systems. Each of the one or more scleral projection systems may comprise a scleral projection light source and a scleral reference object.

[0056] Each scleral reference object may comprise at least one diaphragm comprising one or more apertures. The one or more apertures may be disposed in an aperture pattern. The one or more apertures may comprise a scleral aperture pattern and optionally a corneal aperture pattern. When imaged on the eye or the at least one imaging sensor the scleral aperture pattern may be imaged as one or more scleral locators and the corneal aperture pattern may be imaged as a corneal scatter image.

[0057] Each of the one or more scleral projection systems may further comprise a scleral projection imaging system. The scleral projection imaging system may comprise one or more lens.

[0058] The one or more scleral projection system may be symmetrically mounted on the topographer. The symmetrically mounted scleral projection system may comprise a scleral projection system mounted on either side of the topographer. In one embodiment a scleral projection system is disposed on either side or both sides of the light guide, i.e. a symmetrically mounted left scleral projection system and a symmetrically mounted right scleral projection system. This allows for projection of the aperture pattern onto different portions of said eye surface. [0059] The scleral aperture pattern illuminated by the scleral projection light source may be imaged onto the projection imaging system and onto said scleral portion of said eye surface. The corneal aperture pattern illuminated by the projection light source may also be imaged onto the projection imaging system and onto the cornea.

[0060] The scleral measurement device may further comprise one or more scleral registration reference object projector. The scleral registration reference object projector may comprise a scleral reference light source and a scleral registration reference object. The scleral reference object may comprise a registration reference object light guide which optionally may be provided in the form of two or more concentric rings and may comprise a second Placido disk.

[0061] Light coming from the scleral reference light source and passing through the scleral registration reference object may be reflected from said eye surface and imaged through the imaging system onto the one or more image capture system.

[0062] The light from the scleral reference light source passing through the scleral registration reference object and reflected from said eye surface may form a scleral image. The scleral image may be digitally processed to obtain corneal height information and scleral locations and comprising scleral height information.

[0063] The processed scleral image may be used to combine the comeal height information from the topographer with the scleral height information into a new scleral topographic map. The combination may comprise image registration. Registration may utilise one or more of the scleral locator; the corneal scatter image; and the scleral registration reference image.

[0064] The at least one diaphragm may comprise two or more adjacent registration apertures through which light from the scleral reference light source can propagate and be disposed onto the cornea. In one embodiment the two or more adjacent registration apertures comprise respective sets of one or two or more adjacent transparent round dots. In another embodiment the adjacent registration apertures comprise a set or two or more adjacent transparent and opaque alternating rings concentric to the axis of the central channel, forming a second Placido disk. In a particular embodiment, the two or more adjacent apertures comprise three transparent circular rings. In yet another embodiment, the three transparent circular rings may be used as a reference diaphragm and can be used together with the alternating transparent and opaque annuli.

[0065] The projected scleral aperture pattern on the eye surface and the registration diaphragm may be imaged together on the same image onto the one or more capture system. From such two adjacent locators or dots of the said registration diaphragm, curvature and height information of the reflecting eye surface can be derived.

[0066] The one or more scleral reference object apertures and/or the scleral registration apertures may be imaged on the one or more imaging sensor by the imaging system.

[0067] The scleral measuring device may further apply an algorithm to improve the accuracy of the scleral height information by comparing an eye reference axis of the scleral image to an eye reference axis of a corneal image. Said reference axis may contain rotational information of the eye to the axis of the central channel or between the eye and the central channel.

[0068] In one embodiment, the light guide body and topography illumination source may form the corneal reference object. In a preferred embodiment, the corneal reference object comprises both a corneal reference object projected by the light guide body and topography illumination source for an apical point and the corneal aperture pattern for the for additional corneal reference information.

[0069] In yet another embodiment, said pupil may be captured in both the scleral and corneal image wherein the captured pupil information may provide information of said eye reference axis for additional corneal reference information.

[0070] In still another embodiment, other uniquely identifiable scleral features may be used to combine said corneal and scleral height information.

[0071] In another embodiment, the pupil centre location of the eye relative to the said axis of central channel may be measured to provide reference data for combining said corneal and scleral height information.

[0072] According to any one of the above aspects, the topographer comprises one or more of a housing and a baseplate. The topographer may also comprise a subject rest comprising one or more of a chin rest and forehead rest. The topographer may further comprise an adjustment arm to move the chin rest up and down. The subject rest may also comprise a calibration device attachment to which a calibration device may be attached for calibrating topographer. The topographer may also comprise a manually operated positioner such as, a joystick. The manually operated positioned may move a base unit in two axes; sideways and forward-backward movement. The topographer may be also be moved vertically such as, by rotation of the joystick. The vertical movement may be through a mounting column on which the light guide and other components such as, the topography illumination source; profile imaging system; and topography imaging system are mounted. [0073] According to any one of the above aspects, the topographer may be connected to junction box by a topographer cable. The junction box may be connected to a computer by a computer cable and to a power supply.

[0074] According to any one of the above aspects, the topographer may further comprise a printed wiring board for controlling the topographer and/or communication with the computer. The printed wiring board may be disposed on the mounting column.

[0075] The housing may a protective enclosure around one or more of the base unit; the vertical mounting column; at least part of the light guide body; the external illuminator; and parts of the scleral measuring device.

[0076] Further aspects and/or features of the present invention will become apparent from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0077] In order that the invention may be readily understood and put into practical effect, reference will now be made to embodiments of the present invention with reference to the accompanying drawings, wherein like reference numbers refer to identical elements. The drawings are provided by way of example only, wherein:

[0078] Figure 1 shows a flow chart according to one embodiment of the invention.

[0079] Figures 2A and 2B are schematic diagrams showing one embodiment of a corneal topographer according to the invention. Figure 2A shoes a perspective view of the topographer and Figure 2B shows a close up view of the cone and cone housing.

[0080] Figures 3A and 3B are schematic diagrams showing sectional views of one embodiment of a topographer of the invention.

[0081] Figures 4A, 4B, 4C and 4D are schematic diagrams showing one embodiment of a locator for positioning the lens systems.

[0082] Figure 5A and 5B are schematic diagrams showing a locator according to another embodiment of the invention.

[0083] Figure 6 is a schematic diagram showing a sectional view and light paths of a PRIOR ART device for acquiring comeal profile data.

[0084] Figure 7 is a schematic diagram showing another sectional view and light paths according to an embodiment of the invention for acquiring scleral data.

[0085] Figures 8A, 8B, 8C and 8D are diagrams showing: one embodiment of a profile image (left) and one embodiment of a comeal image (right) (Figure 8A); a representation of the eye displaying an image of the reference object (Figure 8B); a representation of the eye taken with illumination provided by the external illuminator (Figure 8C); a representation of the eye with wearing a contact lens and visualised using fluorescein (Figure 8D; and a representation of the eye showing the meibomian gland (Figure 8E). [0086] Figures 9A and 9B are schematic diagrams showing a sectional view illustrating corneal topography lights paths (Figure 9A) and corneal profile light paths (Figure 9B) according to one embodiment of the invention.

[0087] Figure 10 is a schematic diagram showing a sectional view illustrating corneal topography and corneal profile light paths with additional external illumination according to one embodiment of the invention.

[0088] Figure 11 is another schematic diagram showing a sectional view illustrating corneal and scleral topography lights paths according to one embodiment of the invention. [0089] Figures 12A and 12B are schematic diagrams showing light paths for image registration according to one embodiment of the invention.

[0090] Figures 13 A and 13B are schematic diagrams showing directed reference objects for image registration according to one embodiment of the invention.

[0091] Figure 14 is a schematic diagram showing a front view of a topographer according to one embodiment of the invention.

[0092] Figures 15A and 15B show a commercial embodiment of a light guide and topographer according to the invention.

[0093] Figures 16A and 16B show a corneal height map and combined corneal and scleral height map according to one embodiment of the invention.

[0094] Figures 17A and 17B show one embodiment of a computing device according to the invention.

[0095] Skilled addressees will appreciate that elements in the drawings are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the relative dimensions of some elements in the drawings may be distorted to help improve understanding of embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION [0096] The present invention is directed to a method, device and system for combining scleral and corneal topography data.

[0097] In one broad form, the invention is directed to a method, device and system for combining scleral and corneal topography data wherein scleral data obtained from projection based topography and corneal data obtained from reflection based topography using comeal height data to one or more comeal reference and a scleral registration reference.

[0098] In another broad form, the invention relates to a combined scleral and comeal image obtained by combining projection based scleral topography data and reflection based corneal topography data by registering the scleral topography data with the corneal topography data using comeal height data to one or more corneal reference and a scleral registration reference.

[0099] The present inventors have surprisingly discovered that comeal topography obtained from reflection-based topography, for example placido systems, where the law of reflection off the cornea is used to derive corneal curvature and height data, is more sensitive to curvature changes than other methods and produce a highly accurate comeal height data.

[00100] The invention advantageously applies the above-described advantage of the accuracy of such reflection-based topographers and combines this data with projections onto the sclera. The invention describes processes to combine corneal height data with the scleral height data.

[00101] The invention, compared to some other devices, has also the advantage, that no fluorescein is required to be put on the eye in this process, improving patient comfort and the examination process.

[00102] FIG. 1 shows one embodiment of a method 600 for combining scleral and corneal topography data. Method 600 comprises receiving 602 scleral data obtained from projection based topography and receiving 604 comeal data obtained from reflection based topography.

[00103] Method 600 additionally comprises registering 606 the scleral data and the corneal data using comeal height data and one or more comeal reference comprised in the corneal data and using a scleral registration reference comprised in the scleral data.

[00104] Also provided, see FIGS. 2A and 2B, is a device 100 for combining scleral and corneal topography data. Device 100 comprises one or more processor registering the scleral data and the comeal data using comeal height data and one or more comeal reference comprised in the comeal data and using a scleral registration reference comprised in the scleral data.

[00105] The invention further provides a system for combining scleral and corneal topography data. The system comprises one or more processor for receiving scleral data obtained from projection based topography and corneal data obtained from reflection based topography. The same or a different one or more processor may register the scleral data and the corneal data using corneal height data and one or more corneal reference comprised in the corneal data and using a scleral registration reference comprised in the scleral data.

[00106] Advantageously, a combined image may be constructed and/or displayed from the registered scleral data and the registered corneal data.

[00107] The skilled person readily appreciates that also described is a combined scleral and corneal image which is obtained by combining projection based scleral topography data and reflection based corneal topography data by registering the scleral topography data with the corneal topography data using corneal height data and one or more corneal reference comprised in the corneal data and using a scleral registration reference comprised in the scleral data.

[00108] In one embodiment registration may use an x,y location of an eye apex and a height reference comprised in the corneal data.

[00109] The registration may also use scleral location relative to a capture device reference and a scleral registration reference. The scleral registration reference may coincide with a corneal position but the scleral data and the corneal data are captured independently. The scleral registration reference may be located on the cornea. The capture device reference may be to coordinates to an instrument calibration by lens position. The scleral reference may contain corneal information regarding position and rotation and is comprised in the scleral data.

[00110] Method 100 may further comprise calculating 104 a scleral image axis for the scleral data and calculating a corneal image axis for the corneal data. The calculation of these image axes may provide improved results, particularly where one data set is significantly rotated with respect to the other.

[00111] The scleral data may comprise a different resolution to the corneal data. In a particular embodiment, the corneal data may comprise a higher resolution than the scleral data.

[00112] The scleral data may comprise scleral height data of the anterior eye surface. The scleral height data may be obtained at a resolution of 1 to 10 pm. The resolution may be 1; 2; 3; 4; 5; 6; 7; 8; 9 or 10 pm. The scleral data may comprise a scleral coverage from 11.5 mm diameter to 20 mm diameter. The scleral height data may be up to 6mm. The scleral height may be measured from the corneal apex. The scleral height may be the range for measurements to 20 mm coverage of said eye in an x,y diameter. [00113] Three dimensional (3D) scleral height data may be calculated from the scleral data from x,y coordinates of scleral locations of and the instrument parameters of a calibrated capture device. The scleral height data may be relative to a capture device reference.

[00114] The scleral data and the corneal data may be obtained aligned to an eye reference axis. The scleral height data the corneal height data may be orthogonal or substantially orthogonal.

[00115] The axis calculated may be an eye reference axis. The eye reference axis may be the videokeratoscope (VK) axis or the apex of the optical axis. For placido systems a convenient reference is the VK-axis, seen on the corneal topography image as the centre of the rings. The VK axis is a particular embodiment having the advantage of coinciding with the apex of the corneal height data where all corneal height data is positive. Other references like the apex of the optical axis and/or the visual axis may be used. From the teaching herein a skilled person is readily able to select a suitable axis.

[00116] The corneal data may comprise corneal height data of the anterior eye surface. The corneal height data may comprise data obtained a resolution of 1 to 2 pm. The corneal data may comprise a corneal coverage from 8 to 11 mm or from 8 mm to an edge of the limbus. The corneal data may further comprise corneal reference data. The corneal reference data may comprise a corneal coordinate data set. The corneal height data may be obtained from a reflection image of said eye. The corneal height data may comprise a coverage of 11 mm diameter. The corneal height data may comprise a height of typically 2 to 2.5mm at the coverage.

[00117] The registration may comprise x,y,z translation to a corneal reference. The translation may result in the combined corneal and scleral height data referenced to a corneal reference.

[00118] The registration uses (i) x and y location relative to a capture device reference comprised in the scleral data.

[00119] The registration may use (ii) information on the eye reference axis location relative to a capture device instrument reference comprised in the corneal data.

[00120] A further processing may be applied to improve accuracy for smaller reference deviations above 0.5 deg from the eye references axis, and optionally, enable combining corneal and scleral height data for larger differences, such as 1 deg up to 20 deg of the eye reference axis between the images. This is advantageous, as a range of image height data from different angles of the eye can be combined with increased data density or to obtain data larger contact lens coverage over 18mm. [00121] Figure 16A shows a corneal height map including a reflection on the eye (top) and corneal height map (bottom).

[00122] Figure 16 shows a combined reflection and projection on the eye (top) and a combined corneal and scleral height map (bottom) according to one embodiment of the invention.

[00123] As used herein an “ optical system ” means one or more lenses or other image forming components, mirror, prism, spectral optical filter and/or or aperture for directing, observing, analysing, recording and/or capturing light. It is to be understood that a particular optical system may be comprised of different arrangements of one or more lens or other image forming components, mirror, prism, spectral optical filter and/or aperture and perform the same function. For example, where a particular optical system is described herein as comprising one or more prism it is to be understood that a different construction comprising one or more lens or other image forming components, mirror, prism, spectral optical filter and/or apertures may be substituted for the prism.

[00124] As used herein, an “ imaging system ” means a specific type of optical system, that forms a real or virtual image of an object.

[00125] As used herein a “mire” is a pattern of a reference object whose image, as reflected by the curved surface of the cornea, is used in calculating the topography of the cornea. [00126] One embodiment of a topographer 100 according to the invention is shown in FIG. 1. Topographer 100 comprises a topography light guide or cone 101 accommodated in housing 121. Sturdy support is provided by baseplate 120. A stable platform is provided by subject rest 122 which comprises chin rest 117 and forehead rest 118. An adjustment arm 119 is also provided for moving chin rest up and down. This vertical adjustment allows for different head sizes to be aligned accurately so the height of the eye 106 is lined up with the optical axis of topographer 100.

[00127] Topographer 100 is connected to junction box 160 (not shown) by topographer cable 214. The junction box 160 is in turn connected to a conventional computer 161 (not shown) by computer cable 162 (not shown) inserted into a USB (universal serial bus) port and to a power supply 163 (not shown) by power cable 164 (not shown).

[00128] Subject rest 122 also comprises a calibration device attachment 165 (not shown) to which a calibration device 166 (not shown) may be attached for calibrating topographer 100

[00129] Topographer 100 also comprises a manually operated positioner 167 comprising a joystick 168 which may be used to move base unit 169 in two axes; sideways and forward- backward movement. Additionally, vertical movement is accomplished by rotation of joystick 168. This allows accurate and convenient alignment of topographer 100 with the subject’s eye 106. The vertical movement is through mounting column 169 on which the light guide 101 and other components such as, the light guide lighting array 155, profile imaging system 112 and topography imaging system 123 are mounted.

[00130] As will be described in further detail below, topographer 100 also comprises external illuminator 207 which provides additional light for topography and for additional ophthalmic imaging functions. The external illuminator 207 comprises light sources 208 which are symmetrically mounted at either side of the light guide 101. The light sources 208 may be any suitable light source such as an LED.

[00131] Also further described below is the optional provision of a scleral measurement device 400 comprised in some embodiments of topographer 100. Scleral measurement device 400 comprises one or more scleral projection systems 401 and scleral reference object 402 shown in FIGS. 10 and 11 A. The scleral measurement device may further comprise one or more scleral registration reference object projector 404.

[00132] Also as described below in further detail, the imaging system 123 also comprises one or more actuator 307 (not shown), such as a motor, that rotates wheel 302 to a defined position for alignment in the imaging system optical path.

[00133] Also disposed on the mounting column 169 is a printed wiring board 170 (not shown) used for controlling the topographer 100 and communication with the computer 161. As shown in FIG. 1A and FIG. IB all the internal components are enclosed in housing 121 which forms a protective enclosure around the base unit 169 and the vertical mounting column 170. Additionally, light guide body 102 is partially enclosed within housing 121. [00134] FIG. IB shows light guide 100 and part of the profile imaging system 112. Light guide 100 comprises a light guide body 102 which comprises at least a part of reference object 103 which is illuminated to image the topography annuli or rings as mires 126. [00135] Light guide body 102 is comprised of a transparent media 104. In the embodiment shown in FIG. 2 the transparent media 104 comprises poly (methyl methacrylate) (PMMA). Based on the teaching herein, a skilled person is readily able to select any other suitable transparent media. The transparent media 104 may comprise one more optically homogeneous and transparent media.

[00136] Light guide body 102 comprises a substantially toric or conical external surface 142 shape and a substantially conical inner surface 141 shape. In the embodiment shown in the Figures, the substantially toric or conical shape is a torus or frusto-conical shape comprising central channel 124. The diameter of cone 101 decreases along its length from distal end 115 to proximal end 109. The toric or conical shape means that the distal end diameter is greater than the proximal end diameter so that the concentric transparent annuli 128 and opaque annuli along the length of light guide body 102 reduce in circumference from the distal end 115 to the proximal end 109.

[00137] Light guide body 102 is dimensioned conveniently to fit the human form of the face, with an orifice diameter of the central channel of less than 35 mm, and an overall diameter of the light guide body 102 of less than 70 mm and a length of the light guide body 10 of less than 100 mm. The depth of the topographer 100 is less than 300 mm and the height of the topographer 100 is less than 450mm.

[00138] In another embodiment light guide body 102 is substantially symmetrical and comprises a contoured profile 125 (not shown) at proximal end 109. The contoured profile 125 comprises symmetrical and opposed extensions 145 (not shown) and recesses 146 (not shown). The extensions 145 house at least a part of the directing optical system 108 and at least a part of the reflecting optical system 111. Extensions 145 are disposed at opposing points at the proximal end 109. The recesses 146 are also disposed at opposing points at the proximal end 109. The extensions and recesses may comprise a scalloped edge.

[00139] In another embodiment of any one of the above aspects, at least a part of the directing optical system and at least a part of the reflecting optical system are located opposite each other on the proximal end of light guide body. Significantly, the directing optical system directs light at a right angle to the optical axis.

[00140] Light guide 101 is attached to the topographer 100 through a mounting flange 147 (not shown). The toric or conical shape of the light guide body 102 housing central channel 124 permits exposure of eye 106 to reference object 130 disposed on the interior surface 141.

[00141] FIG. IB shows a front perspective view of part of topographer 100 showing a close up of the region comprising the light guide 101 and making the reference object 103 visible through the central channel 124.

[00142] As shown in the perspective view of FIG. IB and the section view of FIG. 2A, reference object 130 comprises a plurality of annuli or rings in the form of alternating transparent annuli 128 and opaque annuli 129 (represented as dashed lines in the section view of FIG. 2A). In the embodiment shown, reference object 130 comprises a plurality of transparent annuli 128, each adjoined on both sides by an opaque annulus 129, disposed on interior surface 141 along its axial length. Terminal annuli 128, 129 will only be adjoined by a counterpart annuli 129, 128 on a non-terminal side.

[00143] When light guide 101 is illuminated, the plurality of transparent annuli 128 are illuminated and form a virtual image of concentric rings as mires 126 produced by the curvature of the anterior corneal surface 148. By imaging and analysing the imaged concentric ring mires 126 produced by the anterior corneal surface 148 through the imaging system 123 resultant from transparent annuli 128, the topography of the cornea 107 may be determined. In this respect and in this embodiment, reference object 103 may be referred to as a Placido disk.

[00144] The interior surface 141 faces central channel 124. The interior surface 141 and exterior surface 142 of the light guide body 102 may be polished so as to act as a reflective or refractive optical surface.

[00145] The transparent annuli 128 are integral with the light guide body 102. In the embodiment shown, reference object 103 is, or more accurately, the opaque annuli 129 are, painted or otherwise applied onto light guide body 102. In another embodiment, the painting, or other application, may comprise application of opaque annuli 129 and transparent annuli 128. In still another embodiment, reference object 103 may comprise an overlay 149 (not shown) comprising a transparent sheet 151 on which the opaque annuli 134 are comprised. In this embodiment, opaque annuli 129 may be printed on the sheet 151. The overlay 149 is then positioned inside central channel 124 so that the printed opaque annuli 129 extend along the length of the channel 124.

[00146] In the embodiment shown in FIGS. 1A and IB, reference object 103 comprises thirty transparent annuli 128. From the teaching herein a skilled person is readily able to select other suitable reference objects and other suitable numbers of mire producing features. For example, reference object 103 may comprise 5 to 50, 10 to 40 or 20 to 35 transparent rings or other mire producing feature.

[00147] FIGS. 2A and 8A, also show that in order to provide even illumination of the rings 126, light guide body 102 may be comprised of a plurality of light guide segments 130, In the embodiment shown in FIGS. 2A and 8 A, light guide body 102 comprises three segments 130i, 130ii and 130iii. Each segment 130 comprises a respective coupling efficiency matched to provide even illumination of each transparent annuli 126 along the length of the reference object 103. Each segment 130 may comprise any number of transparent annuli 128 and opaque annuli 129. [00148] In other embodiments, light guide body 102 may comprise one, two, four, five, six, seven, eight, nine, ten segments or more than ten segments 130. The number of segments 130 may be selected to provide adequate illumination.

[00149] In the embodiment shown, each segment 130 comprises a coupling efficiency to produce an evenly illuminated ring image on the at least one imaging sensor 1116.

[00150] Importantly, light guide body 102 comprises a higher coupling efficiency compared to that of radiation of the topography illumination source 105, including the distributed illumination source 200 and profile optics illumination source 201, into free space.

[00151] As shown in FIG. 8A, each light guide segment 130 and part or all of the exterior surface 142 may comprise an optically isolating cover 131 to prevent leaking light into the other light guide segments and or prevent or reduce light coupling out of the light guide body 102.

[00152] Segment 130(i) comprises a target segment which may be coloured or otherwise comprise a visible indicia to provide a target for the gaze of eye 106 looking through channel 124. In the embodiment shown, although not visible in the black and white figures, target segment 130(i) is coloured green. Target segment 130(i) is shown disposed at a distal end of light guide body 102. All other segments 130(i),(ii) may be of the same transparent material but different from 130(i) in dimension and coupling efficiency, and preferably clear.

[00153] FIG. 2A shows the components for corneal topography according to one embodiment of the invention, while FIG. 2B shows the components for profile imaging according to one embodiment of the invention. Further explanation is provided by FIGS. 8A and 8B which show the optical paths for the central topography optical system 150 and the profile system 172, respectively.

[00154] As shown in both FIGS. 2A and 2B, illumination of topographer 100 is provided by light guide lighting array 155 which comprises a topography illumination source 105 (FIG. 2A) and a profile optics illumination source 201 (FIG. 2B). Light guide body 102 is illuminated by topography illumination source 105. Significantly, the topography illumination source 105 and the profile optics illumination source 201 are resolvable. The topography illumination source 105 and profile optics illumination source 201 may emit light at sufficiently different wavelengths so no interference occurs of the images on the at least one imaging sensor 116. [00155] Topography illumination source 105 illuminates reference object 103 or at least the transparent annuli 128. That is, the topography illuminations source 105 illuminates light guide body 102 to provide light for illumination of the cornea 107 and for projection of reference object 103 onto the anterior corneal surface 148.

[00156] Topography illumination source 105 comprises a distributed illumination source 200 and thereby comprises a plurality of separate illumination sources in the form of topography illumination LEDs 153, which emit polychromatic or white light. The plurality of LEDs 153 are comprised in two or more concentric rings of LEDs 153 comprised on a printed board (PCB) 203. Although no corresponding figure is provided, in the embodiment shown, topography illumination source 105 comprises an outer ring 105(a) and inner ring 105(b).

[00157] FIG. 8A shows three optical paths of light emitted by the topography illumination source 105 comprised of LEDs 153. Some light has an optical path such as, topography optical path 206a, and is entirely coupled out of the light guide body 102 from exterior surface 142. Other light partially takes topography optical path 206b in which light rays are partially coupled out of light guide body 102 from exterior surface 142 and partially takes topography optical path 206c in which it is reflected off the external surface 142 towards the interior surface 141 upon eye 106 before traversing central channel 124 to be incident on the at least one imaging sensor 116. That is, the light within the light guide body 102 can be divided at the exterior surface 142 and partially refracted and disposed to the surrounding environment. Optical path 206d shows light rays that do not pass the exterior surface 142 and traverse towards interior surface 141, are incident upon eye 106, before traversing central channel 124 and central imaging system 123 to be incident on the at least one imaging sensor 116 to form corneal image 204. That is, mires 126 are imaged on imaging sensor 116.

[00158] Turning to FIG. 2B, profile optics illumination source 201 is shown to comprise a profile point light source 202, in the form of a single LED, emitting infra-red light. The light from point light source 202 traverses light guide body 202 and is directed by directing optical system across the corneal profile 110 to be received by the reflecting optical system 111 and directed to the profile imaging system 112 for direction to capture system 113 and at least one imaging sensor 116 where profile image 205 is formed and captured.

[00159] Directing optical system 108 is shown to comprise a mirror 133 and reflecting optical system 111 is shown to comprise a prism 143. In other embodiments, this arrangement is reversed with the directing optical system 108 comprising a prism and reflecting optical system 111 comprising a mirror.

[00160] The profile imaging system 112 is shown to comprise mirrors 133 and other components to direct the light propagation direction vector 134 to capture system 113.

From FIGS. 2A and 2B it can bee see that imaging is performed with capture system 113 which is shown to comprise at least one imaging sensor 116. In other embodiments, capture system 113 comprises two or more imaging sensors, which may be provided in the form of a topography imaging sensor 173 (not shown) and a profile imaging sensor 152 (not shown).

[00161] FIG. 2A also shows that the relative position of light guide body 201 and eye 106 may be moved such as, with positioner 167. This is advantageous as it allows convenient positioning of eye 106 for each respective optical system 300a, 300b, 300c, 300d, comprised in the interchangeable optical system 300. In the embodiment shown in FIGS. 3A, 3B, 3C, and 3D, interchangeable optical system 300 is disposed on a locator 301 in the form of a wheel 302 which can rotate in each direction to accurately align each respective optical system 300a, 300b, 300c, 300d, in the central channel and with one or more capture system 113.

[00162] As shown in FIG. 3A, wheel 302 comprises a fenestration 308 for the axis of the central channel 144 for the central topography system 150.

[00163] Wheel 302 may be rotated in either direction, clockwise or counter-clockwise, as shown by the arrow on FIG. 3 A.

[00164] Wheel 302 comprises indexing locations 303 which engages with one or more teeth. The one or more teeth 309, which in the embodiment shown in FIGS. 3A, 3B, 3C and 3D comprises a sole tooth, may be disposed on pivoting lever 305 which acts as a spring 304.

[00165] Wheel 302 comprises one or more indexing location 303 for precise positioning of each of the two optical systems. In the embodiment shown in FIGS. 3A, 3B, 3C and 3D, the interchangeable optical system 300 comprises four optical systems 300a, 300b, 300c, and 300d and four respective indexing locations 303a, 303b, 303c, and 303d. By selecting an appropriate indexing location 303a, 303b, 303c, 303d, for engagement with one or more teeth 309, a respective optical system 300a, 300b, 300c, 300d, may be accurately positioned with respect to the central channel 124 for imaging eye 106.

[00166] FIG. 3A shows the one or more teeth 309 not engaged with wheel 302 which is in transition between two indexing locations 303. FIG. 3B shows the wheel 302 having turned further so that the one or more teeth 309 is now engaged with when 302 and pivoting lever 305 has sprung back to engage with wheel 302.

[00167] FIG. 3D shows another embodiment of locator 301 which instead of using a pivoting lever 305 uses a sliding element 306.

[00168] Although not shown, locator 301 further comprises one or more actuator 307 in the form of a motor 421 for effecting the rotation.

[00169] FIG. 4 shows another embodiment of locator 301 comprising a motor 421 which drives transmission belt 422 to effect rotation of wheel 302. In another embodiment, the wheel 302 comprises a gear.

[00170] In the embodiment shown in FIG. 3D the interchangeable optical system 300 comprises six optical systems. In other embodiments, two, three, five, seven, eight, nine, ten, or more than ten optical systems may be comprised.

[00171] Locator 301 is a backlash free locator which advantageously provides accurate location and prevents or at least reduces undesired movement.

[00172] Advantageously, the light guide body 102 is illuminated to a different colour dependent on the light emitted by the lighting array 155. The light emitted by the lighting array 155 may comprise different distinguishable colors which indicate a modality in use such as, central topography system 150, profile system 172, or a respective one of the interchangeable optical systems 300.

[00173] From the above a skilled person will appreciate that the visible light portion used for light propagation for the illumination of eye 106 can be split on its exterior surface and coupled out of the light guide body 102 to the surrounding areas and be visible to the user or patient. The coupled out light may also be used for illuminating the eye 106 in addition to other illumination means for imaging the eye 106 or surrounding areas of the eye 106 for imaging purposes.

[00174] The light coupled out and visible to the user or tested subject can contain information on the operating state of the topographer 100 or additional information. The information of the light may be presented in form of color as the preferred embodiment, but also can contain other light modulations like light pulses or changing brightness. [00175] The light guide body 102 also provides a portion of the light path propagation for illumination of the corneal profile 110 and imaging of the corneal image 204 onto the at least one imaging sensor 116.

[00176] FIG. 7A shows a profile image 205 (left hand side) and a corneal image 204 (right hand side). FIG. 7A also shows that, advantageously, the profile data comprises profile contour 137 and apex location 138. A reference location 139 may be applied to determine the location of the eye 106 relative to the reference object 130 or to the central imaging system 123. These images 204, 205 are able to be reconstructed with the data captured from one or more capture system 113.

[00177] FIGS. 7B, 7C, 7D, and 7E show example information and images that may be obtained with the interchangeable optical systems 300. FIG. 7B shows an anterior image of the eye. FIG. 7C shows a corneal image. FIG. 7D shows a contact lens fitting image and FIG. 7E shows a meibomian gland image. FIGS. 7B, 7C, 7D, and 7E may for example be obtained with optical systems 300a, 300b, 300c, and 300d, respectively.

[00178] Another significant advantage of the interchangeable optical systems 300 is that each optical system 300a, 300b, 300c, 300d etc is complete and does not require any other imaging elements, in isolation or shared between each component interchangeable optical system 300a, 300b, 300c, 300d etc or from topographer 100 generally. This allows more than one imaging function to be performed.

[00179] FIG. 5 shows a schematic diagram of a prior art device for imaging a corneal profile. This sectional view shows that the prior art profile optics and the respective optical path is exterior, or mostly exterior, to the light guide body.

[00180] This contrasts with profile system 172 and profile optical path 206 shown in FIG. 8B which traverse the light guide body 102.

[00181] FIG. 8B shows, profile optical path 206 of light emitted by the profile optics illumination source 201. Light traverses through the transparent media 104 to the directing optical system 108 and reflecting optical system 111 mounted at opposing points on proximal end 109 of light guide body 102. The directing optical system 108 comprises a mirror 143 which directs the transmitted light across the corneal profile 110 along that part of the profile optical path 206 between mirror 143 and the prism 143 comprised in the reflecting optical system 111.

[00182] Reflecting optical system 111 reflects the directed light from the directing optical system 108 that has traversed the corneal profile 110 and targets it back through light guide body 102 to profile imaging system 112 and onto one or more capture system 113.

[00183] At least a portion of the light captured by directing optical system 108 is incident on reflecting optical system 111 disposed adjacent the distal end 110 of cone 100. The profile image 206 comprises information on the distance of the subject eye 190 from a reference point. The distance information is used together with the information comprised in the corneal image to obtain corneal curvature information. The distance information is derived by measuring the profile contour 137 of the profile image 205 and comparing its apex location 138 relative to a reference location on the profile image 205.

[00184] As shown in FIG. 2B, the profile imaging system 112 also comprise one or more focusing lens 135 to focus the profile plane of eye 106 onto the at least one imaging sensor 116. The profile imaging system 112 may be designed to correct for the optic path length through the light guide body 102.

[00185] Also shown in FIG. 2B is that profile imaging system 112 further comprises an optical filter 254 which only or substantially only transmits the infra-red light from the profile optics illumination light source 201.

[00186] The surfaces on the light guide body 102 used in the light propagation of the eye profile imaging are substantially perpendicular to the light propagation direction vector 134. That is directing optical system and reflecting optical system reflect light substantially at a right angle, and both propagation direction vectors intercept the axis of central channel at a right angle.

[00187] It may be desirable to provide additional light to the central topography system 105. FIG. 6 shows a schematic diagram of a cross section of topographer 100 showing the relative position of an external illuminator 207 with respect to the light guide body.

[00188] External illuminator 207 is outside the plane of the light guide body 102, and thereby positionally distinguished from centrally or internally positioned lighting array 155 and topography illumination source and profile imaging illumination source 201, which are in the same plane as light guide body 102.

[00189] External illuminator 207 comprises light sources 208 which provide the additional illumination as shown in FIGS. 6 and 9. In the embodiment shown, light sources 208 comprise LEDs.

[00190] Turning to FIGS. 10, 11A and 11B, the topographer 100 may further comprise a scleral measurement device 400. The scleral measurement device 400 comprises one or more scleral projection systems 401, each of which comprise a scleral projection light source 406 and a scleral reference object 402.

[00191] The scleral reference objects 402 comprise at least one diaphragm 415 comprising one or more apertures 415a. The one or more apertures 415a are disposed in a scleral aperture pattern 405 and optionally a corneal aperture pattern 414. When imaged on eye 106 or the at least one imaging sensor 116 the scleral aperture pattern 405 may be imaged as one or more scleral locators 418 and the corneal aperture pattern 414 may be imaged as a comeal scatter image 419. As shown in FIG. 11A, the corneal scatter image 419 goes through the comeal so the measurement is through the eye in a volume scatter.

[00192] The one or more scleral projection systems 401 further comprise a scleral projection imaging system 403 which is shown to comprise one or more lens.

[00193] In the embodiment shown in FIG. 10, the one or more scleral projection systems 401 comprise two symmetrically disposed scleral projection systems 401, one mounted on each side of topographer 100. The symmetrically mounted scleral projection systems 401 may comprise a scleral projection system 401 mounted on either side of topographer 100. In one embodiment a scleral projection system 401 is disposed on either side or both sides of the light guide body 102, i.e. a symmetrically mounted left scleral projection system 401 and a symmetrically mounted right scleral projection system 401. This allows for projection of the aperture pattern 405, 414 onto different portions of said eye surface. [00194] The scleral aperture pattern 405 illuminated by the scleral projection light source

406 may be imaged onto the scleral projection imaging system 403 and onto said scleral portion of said eye surface. The corneal aperture pattern 414 illuminated by the projection light source 406 may also be imaged onto the projection imaging system 403 and onto the cornea 107.

[00195] The scleral measurement device 400 further comprises one or more scleral registration reference object projector 404 which comprises a scleral reference light source 408 and a scleral registration reference object 407. The scleral registration reference object

407 may comprise a registration reference object light guide 409 which optionally may be provided in the form of two or more concentric rings and may comprise a second Placido disk. Light coming from the scleral reference light source 408 and passing through the scleral registration reference object 407 may be reflected from said eye surface and imaged through the imaging system 123 onto the one or more image capture system 113.

[00196] The light from the scleral reference light source 408 passing through the scleral registration reference object 407 and reflected from said eye surface forms a scleral image 410 which is digitally processed to obtain corneal height information and scleral locations and comprising scleral height information. A reader familiar with corneal topography understands, that height information and curvature information of the eye 106 are conjugate and contain the same information. The scleral height information and scleral curvature information may be converted from one to another by applying commonly known mathematical means. [00197] The processed scleral image 410 may be used to combine the corneal height information from the topographer 100 with the scleral height information into a new scleral topographic map. The combination may comprise image registration. Registration may utilise one or more of the scleral locator 418; the corneal scatter image 419; and the scleral registration reference image 420.

[00198] The registration diaphragm 423 comprises two or more adjacent registration apertures 423a through which light from the scleral reference light source 408 can propagate and be disposed onto cornea 107. In the embodiment shown, the two or more adjacent registration apertures 423a comprise respective sets of one or two or more adjacent transparent round dots. In other embodiments, the adjacent registration apertures 423a comprise a set or two or more adjacent transparent and opaque alternating rings concentric to the axis of the central channel 124, forming a second Placido disk 416. As shown in FIG. 13, the two or more adjacent registration apertures 423a comprise three transparent circular rings. In yet another embodiment, the circular rings may be used as a reference diaphragm and can be used together with the alternating circular rings 418. [00199] The projected scleral aperture pattern 405 on the eye surface and the registration diaphragm 423 may be imaged together on the same image onto the one or more capture system 113. From such two adjacent rings or dots of the said registration diaphragm 423, curvature and height information of the reflecting eye surface can be derived.

[00200] The scleral measuring device 400 may further apply an algorithm to improve the accuracy of the scleral height information by comparing an eye reference axis of the scleral image 410 to an eye reference axis of a corneal image 204. Said reference axis may contain rotational information of the eye 106 to the axis of the central channel 124 or between the eye 106 and the central channel 122.

[00201] In one embodiment, the light guide body and topography illumination source may form the corneal reference object. In a preferred embodiment, the corneal reference object comprises both a corneal reference object projected by the light guide body and topography illumination source for an apical point and the corneal aperture pattern for the for additional corneal reference information.

[00202] One embodiment of a computing device 500 suitable for use in the present invention is shown in FIGS. 17A and 17B. In the embodiment shown computing device 500 comprises a computer module 501 comprising input devices such as a keyboard 502, a mouse pointer device 503, a scanner 526, an external hard drive 527, and a microphone 580; and output devices including a printer 515, a display device 514 and loudspeakers 517. In some embodiments video display 514 may comprise a touchscreen.

[00203] A Modulator-Demodulator (Modem) transceiver device 516 may be used by the computer module 501 for communicating to and from a communications network 520 via a connection 521. The network 520 may be a wide-area network (WAN), such as the Internet, a cellular telecommunications network, or a private WAN. Through the network 520, computer module 501 may be connected to other similar computing devices 590 or server computers 591. Where the connection 521 is a telephone line, the modem 516 may be a traditional “dial-up” modem. Alternatively, where the connection 521 is a high capacity (e g.: cable) connection, the modem 516 may be a broadband modem. A wireless modem may also be used for wireless connection to network 520.

[00204] The computer module 501 typically includes at least one processor 505, and a memory 506 for example formed from semiconductor random access memory (RAM) and semiconductor read only memory (ROM). The module 501 also includes a number of input/output (I/O) interfaces including: an audio-video interface 507 that couples to the video display 514, loudspeakers 517 and microphone 580; an I/O interface 513 for the keyboard 502, mouse 503, scanner 526 and external hard drive 527; and an interface 508 for the external modem 516 and printer 515. In some implementations, modem 516 may be incorporated within the computer module 501, for example within the interface 508. The computer module 501 also has a local network interface 511 which, via a connection 523, permits coupling of the computing device 500 to a local computer network 522, known as a Local Area Network (LAN).

[00205] As also illustrated, the local network 522 may also couple to the wide network 520 via a connection 524, which would typically include a so-called “firewall” device or device of similar functionality. The interface 511 may be formed by an Ethernet circuit card, , WiFi, including WiFi HaLow, a Bluetooth wireless arrangement or an IEEE 802.11 wireless arrangement or other suitable interface, such as Zigbee and Morse Micro, which may be implemented in (Industrial) Internet of Things ((I)IoT) or home automation technology.

[00206] The EO interfaces 508 and 513 may afford either or both of serial and parallel connectivity, the former typically being implemented according to the Universal Serial Bus (USB) standards and having corresponding USB connectors (not illustrated).

[00207] Storage devices 509 are provided and typically include a hard disk drive (HDD) 510. Other storage devices such as, an external HD 527, a disk drive (not shown) and a magnetic tape drive (not shown) may also be used. An optical disk drive 512 is typically provided to act as a non-volatile source of data. Portable memory devices, such as optical disks (e g.: CD-ROM, DVD, Blu-Ray Disc), USB-RAM, external hard drives and floppy disks for example, may be used as appropriate sources of data to the computing device 500. Another source of data to computing device 500 is provided by the at least one server computer 591 through network 520.

[00208] The components 505 to 513 of the computer module 501 typically communicate via an interconnected bus 504 in a manner that results in a conventional mode of operation of computing device 500. In the embodiment shown in FIGS. 17A and 17B, processor 505 is coupled to system bus 504 through connections 518. Similarly, memory 506 and optical disk drive 512 are coupled to the system bus 504 by connections 519. Examples of copmuting devices 500 on which the described arrangements can be practiced include IBM-PC's and compatibles, Sun Sparc stations, Apple computers; smart phones; tablet computers or like a device comprising a computer module like computer module 501 or (Industrial) Internet of Things ((I)IoT) home automation technology such as, zigbee and morse micro access points and/or connected devices. It is to be understood that when computing device 500 comprises a smart phone or a tablet computer, display device 514 may comprise a touchscreen and other input and output devices may not be included such as, mouse pointer device 503; keyboard 502; scanner 526; and printer 515.

[00209] FIG. 17B is a detailed schematic block diagram of processor 505 and a memory 534. The memory 534 represents a logical aggregation of all the memory modules, including the storage device 509 and semiconductor memory 506, which can be accessed by the computer module 501 in FIG. 17A.

[00210] The methods of the invention may be implemented using computing device 500 wherein the methods may be implemented as one or more software application programs 533 executable within computer module 501. In particular, the steps of the methods of the invention may be effected by instructions 531 in the software carried out within the computer module 501

[00211] The software instructions 531 may be formed as one or more code modules, each for performing one or more particular tasks. The software 533 may also be divided into two separate parts, in which a first part and the corresponding code modules performs the method of the invention and a second part and the corresponding code modules manage a graphical user interface between the first part and the user. [00212] The software 533 may be stored in a computer readable medium, including in a storage device of a type described herein. The software is loaded into the computing device 500 from the computer readable medium or through network 521 or 523, and then executed by computing device 500. In one example the software 533 is stored on storage medium 525 that is read by optical disk drive 512. Software 533 is typically stored in the HDD 510 or the memory 506.

[00213] A computer readable medium having such software 533 or computer program recorded on it is a computer program product. The use of the computer program product in the computing device 500 preferably effects a device or apparatus for implementing the methods of the invention.

[00214] In some instances, the software application programs 533 may be supplied to the user encoded on one or more disk storage medium 525 such as a CD-ROM, DVD or Blu- Ray disc, and read via the corresponding drive 512, or alternatively may be read by the user from the networks 520 or 522. Still further, the software can also be loaded into the computing device 500 from other computer readable media. Computer readable storage media refers to any non-transitory tangible storage medium that provides recorded instructions and/or data to the computer module 501 or computing device 500 for execution and/or processing. Examples of such storage media include floppy disks, magnetic tape, CD-ROM, DVD, Blu-ray Disc, a hard disk drive, a ROM or integrated circuit, USB memory, a magneto-optical disk, or a computer readable card such as a PCMCIA card and the like, whether or not such devices are internal or external of the computer module 501. Examples of transitory or non-tangible computer readable transmission media that may also participate in the provision of software application programs 533, instructions 531 and/or data to the computer module 501 include radio or infra-red transmission channels as well as a network connection 521, 523, 534, to another computer or networked device 590, 291 and the Internet or an Intranet including email transmissions and information recorded on Websites and the like.

[00215] The second part of the application programs 533 and the corresponding code modules mentioned above may be executed to implement one or more graphical user interfaces (GUIs) to be rendered or otherwise represented upon display 514. Through manipulation of, typically, keyboard 502, mouse 503 and/or screen 514 when comprising a touchscreen, a user of computing device 500 and the methods of the invention may manipulate the interface in a functionally adaptable manner to provide controlling commands and/or input to the applications associated with the GUI(s). Other forms of functionally adaptable user interfaces may also be implemented, such as an audio interface utilizing speech prompts output via loudspeakers 517 and user voice commands input via microphone 580. The manipulations including mouse clicks, screen touches, speech prompts and/or user voice commands may be transmitted via network 520 or 522.

[00216] When the computer module 201 is initially powered up, a power-on self-test (POST) program 550 may execute. The POST program 550 is typically stored in a ROM 549 of the semiconductor memory 506. A hardware device such as the ROM 549 is sometimes referred to as firmware. The POST program 550 examines hardware within the computer module 2501 to ensure proper functioning, and typically checks processor 505, memory 534 (509, 506), and a basic input-output systems software (BIOS) module 551, also typically stored in ROM 549, for correct operation. Once the POST program 550 has run successfully, BIOS 551 activates hard disk drive 510. Activation of hard disk drive 510 causes a bootstrap loader program 552 that is resident on hard disk drive 510 to execute via processor 505. This loads an operating system 553 into RAM memory 506 upon which operating system 553 commences operation. Operating system 553 is a system level application, executable by processor 505, to fulfill various high level functions, including processor management, memory management, device management, storage management, software application interface, and generic user interface.

[00217] Operating system 553 manages memory 534 (509, 506) in order to ensure that each process or application running on computer module 501 has sufficient memory in which to execute without colliding with memory allocated to another process. Furthermore, the different types of memory available in the computing device 500 must be used properly so that each process can run effectively. Accordingly, the aggregated memory 534 is not intended to illustrate how particular segments of memory are allocated, but rather to provide a general view of the memory accessible by computer module 501 and how such is used.

[00218] Processor 505 includes a number of functional modules including a control unit 539, an arithmetic logic unit (ALU) 540, and a local or internal memory 548, sometimes called a cache memory. The cache memory 548 typically includes a number of storage registers 544, 545, 546 in a register section storing data 547. One or more internal busses 541 functionally interconnect these functional modules. The processor 505 typically also has one or more interfaces 542 for communicating with external devices via the system bus 504, using a connection 518. The memory 534 is connected to the bus 504 by connection 519. [00219] Application program 533 includes a sequence of instructions 531 that may include conditional branch and loop instructions. Program 533 may also include data 532 which is used in execution of the program 533. The instructions 531 and the data 532 are stored in memory locations 528, 529, 530 and 535, 536, 537, respectively. Depending upon the relative size of the instructions 531 and the memory locations 528-530, a particular instruction may be stored in a single memory location as depicted by the instruction shown in the memory location 530. Alternately, an instruction may be segmented into a number of parts each of which is stored in a separate memory location, as depicted by the instruction segments shown in the memory locations 528 and 529.

[00220] In general, processor 505 is given a set of instructions 543 which are executed therein. The processor 505 then waits for a subsequent input, to which processor 505 reacts by executing another set of instructions. Each input may be provided from one or more of a number of sources, including data generated by one or more of the input devices 502, 503, or 514 when comprising a touchscreen, data received from an external source across one of the networks 520, 522, data retrieved from one of the storage devices 506, 509 or data retrieved from a storage medium 525 inserted into the corresponding reader 512. The execution of a set of the instructions may in some cases result in output of data. Execution may also involve storing data or variables to the memory 534.

[00221] The disclosed arrangements use input variables 554 that are stored in the memory 534 in corresponding memory locations 555, 556, 557, 558. The described arrangements produce output variables 561 that are stored in the memory 534 in corresponding memory locations 562, 563, 564, 565. Intermediate variables 568 may be stored in memory locations 559, 560, 566 and 567.

[00222] The register section 544, 545, 546, the arithmetic logic unit (ALU) 540, and the control unit 539 of the processor 505 work together to perform sequences of micro operations needed to perform "fetch, decode, and execute" cycles for every instruction in the instruction set making up the program 533. Each fetch, decode, and execute cycle comprises:

(a) a fetch operation, which fetches or reads an instruction 531 from memory location 528, 529, 530;

(b) a decode operation in which control unit 539 determines which instruction has been fetched; and

(c) an execute operation in which the control unit 539 and/or the ALU 540 execute the instmction. [00223] Thereafter, a further fetch, decode, and execute cycle for the next instruction may be executed. Similarly, a store cycle may be performed by which the control unit 539 stores or writes a value to a memory location 532.

[00224] Each step or sub-process in the methods of the invention may be associated with one or more segments of the program 533, and may be performed by register section 544- 546, the ALU 540, and the control unit 539 in the processor 505 working together to perform the fetch, decode, and execute cycles for every instruction in the instruction set for the noted segments of program 533.

[00225] One or more other computers 590 may be connected to the communications network 520 as seen in FIG. 17A. Each such computer 590 may have a similar configuration to the computer module 501 and corresponding peripherals.

[00226] One or more other server computer 591 may be connected to the communications network 520. These server computers 591 response to requests from the computing device 200 or other server computers to provide information.

[00227] Method 100 may alternatively be implemented in dedicated hardware such as one or more integrated circuits performing the functions or sub functions of the described methods. Such dedicated hardware may include graphic processors, digital signal processors, or one or more microprocessors and associated memories.

[00228] It will be understood that in order to practice the methods of the invention as described above, it is not necessary that the processors and/or the memories of the processing machine be physically located in the same geographical place. That is, each of the processors and the memories used in the invention may be located in geographically distinct locations and connected so as to communicate in any suitable manner. Additionally, it will be understood that each of the processor and/or the memory may be composed of different physical pieces of equipment. Accordingly, it is not necessary that a processor be one single piece of equipment in one location and that the memory be another single piece of equipment in another location. That is, it is contemplated that the processor may be two pieces of equipment in two different physical locations. The two distinct pieces of equipment may be connected in any suitable manner. Additionally, the memory may include two or more portions of memory in two or more physical locations.

[00229] To explain further, processing as described above is performed by various components and various memories. It will be understood, however, that the processing performed by two distinct components as described above may, in accordance with a further embodiment of the invention be performed by a single component. Further, the processing performed by one distinct component as described above may be performed by two distinct components. In a similar manner, the memory storage performed by two distinct memory portions as described above may, in accordance with a further embodiment of the invention, be performed by a single memory portion. Further, the memory storage performed by one distinct memory portion as described above may be performed by two memory portions.

[00230] Further, various technologies may be used to provide communication between the various processors and/or memories, as well as to allow the processors and/or the memories of the invention to communicate with any other entity, i.e., so as to obtain further instructions or to access and use remote memory stores, for example. Such technologies used to provide such communication might include a network, the Internet, Intranet, Extranet, LAN, an Ethernet, a telecommunications network (e.g., a cellular or wireless network) or any client server system that provides communication, for example. Such communications technologies may use any suitable protocol such as TCP/IP, UDP, or OSI, for example.

[00231] Advantageously, the pupil 413 may be captured in both the scleral image 410 and corneal image 204 wherein the captured pupil information may provide information of said eye reference axis. In addition, or alternatively, other uniquely identifiable scleral features may be used to combine said corneal and scleral height information.

[00232] Also, pupil centre location of the eye 106 relative to the said axis of central channel 124 may be measured to provide reference data for combining said corneal and scleral height information.

[00233] The utilisation of the scleral measurement device 400 as part of topographer 100 allows the scleral data to be combined with the corneal topography data. Advantageously, this does not rely on scatter image and instead uses a reflection off the cornea. Additionally, the relative pupil location of both eyes may be measured to provide reference data for image registration.

[00234] One advantage of the present invention is that, because the illumination is no longer external to the light guide body 102, the diameter at the proximal end 113 can be reduced. This allows closer proximity of corneal surface 148 to the light guide body 102 and hence analysis of a larger corneal portion.

[00235] Another advantage of the present invention is that the illumination no longer causes shadowing that affects the distribution of light. The present invention also greatly reduces the number of components required for illumination and the complexity of manufacture.

[00236] In this specification, the terms “comprises”, “comprising” or similar terms are intended to mean a non-exclusive inclusion, such that an apparatus that comprises a list of elements does not include those elements solely, but may well include other elements not listed.

[00237] Throughout the specification the aim has been to describe the invention without limiting the invention to any one embodiment or specific collection of features. Persons skilled in the relevant art may realize variations from the specific embodiments that will nonetheless fall within the scope of the invention.

Claims

CLAIMS The Claims defining the invention are as follows:

1. A method for combining scleral and corneal topography data, the method comprising: receiving scleral data obtained from projection based topography and corneal data obtained from reflection based topography; and registering the scleral data and the corneal data using corneal height data and one or more corneal reference comprised in the corneal data and using a scleral registration reference comprised in the scleral data.

2. A device for combining scleral and corneal topography data, the device comprising: one or more processor for registering scleral data and corneal data using corneal height data and one or more corneal reference comprised in the corneal data and using a scleral registration reference comprised in the scleral data.

3. An ophthalmol ogical topographer comprising: a projection based topographer comprising a reference object; a topography illumination source illuminating the reference object; an imaging system imaging the reference object projected onto said eye surface through a central channel in the light guide body to generate corneal data; a scleral measurement device comprising one or more scleral projection systems, each of the one or more scleral projection systems comprising a scleral projection light source and a scleral reference object to generate scleral data; one or more processor to register the scleral data and the corneal data using corneal height data and one or more corneal reference comprised in the corneal data and using a scleral registration reference comprised in the scleral data.

4. A system for combining scleral and corneal topography data, the system comprising: one or more processor for receiving scleral data obtained from projection based topography and corneal data obtained from reflection based topography; and one or more processor for registering the scleral data and the corneal data using corneal height data and one or more corneal reference comprised in the corneal data and using a scleral registration reference comprised in the scleral data.

4. The method, device or system according to claims 1 to 4 further comprising: constructing and/or displaying a combined image from the registered scleral data and the registered corneal data.

6. The method, device or system according to claims 1 to 5 further comprising: one or more display for displaying the combined image may be further comprised.

7. A combined scleral and corneal image obtained by combining projection based scleral topography data and reflection based corneal topography data registering the scleral data and the corneal data using corneal height data and one or more corneal reference comprised in the corneal data and using a scleral registration reference comprised in the scleral data.

8. The method, device, system or image according to any one of claims 1 to 7 wherein registration uses a coordinate system.

9. The method, device or system according to any one of claims 1 to 8 wherein registration uses scleral location relative to a capture device reference and a scleral registration reference.

10. The method, device or system according to any one of claims 1 to 9 wherein the scleral registration reference coincides with a corneal position and wherein the scleral data and corneal data are captured independently.

11. The method, device or system according to claim 10 wherein the scleral registration reference is located on the cornea.

12. The method, device or system according to claim 10 or claim 11 wherein scleral capture device reference may be to coordinates to an instrument calibration by lens position.

13. The method according to any one of claims 1 to 12 further comprise the step of calculating a scleral image axis for the scleral data and calculating a corneal image axis for the corneal data.

14. The device or system according to any one of claims 12 to 13 further comprising one or more processor for calculating a scleral image axis for the scleral data and calculating a corneal image axis for the corneal data.

15. The method, device or system according to any one of claims 1 to 14 further comprising: displaying the combined image on a visual display.

16. The method, device or system according to any one of claims 1 to 15 wherein the scleral data comprises a different resolution to a resolution of the corneal data.

17. The method, device or system according to any one of claims 1 to 16 wherein the scleral height data is obtained at a resolution of 1 to 10 pm.

18. The method, device or system according to any one of claims 1 to 17 wherein three dimensional (3D) scleral height data is calculated from the scleral data from x,y coordinates of scleral locations of and the instrument parameters of a calibrated capture device.

19. The method, device or system according to any one of claims 1 to 18 wherein the scleral data and the corneal data are obtained aligned to an eye reference axis.

20. The method, device or system according to any one of claims 1 to 19 wherein the axis calculated is an eye reference axis.

21. The method, device or system according to any one of claims 1 to 18 wherein the registration comprises x,y,z translation to a corneal reference and/or angular rotation.

22. The method, device or system according to any one of claims 1 to 21 wherein the registration uses (i) x,y, z location relative to a capture device reference comprised in the scleral data.

23. The method, device or system according to any one of claims 1 to 21 wherein the registration uses (ii) information on the eye reference axis location relative to a capture device instrument reference comprised in the corneal data.

24. The method, device or system according to claim 22 and 23.