Ophthalmic imaging method, apparatus and system

Abstract

To provide an improved light guide part of an ophthalmic topographer.SOLUTION: The light guide comprises a light guide body 102 comprising a reference object 103, a topographical illumination source for illuminating the light guide body and the reference object, wherein the illuminated light guide body guides light for illumination of an eye to be measured, guiding optics housed within a proximal end of the light guide body for guiding light from the light guide body across a corneal contour of the eye, and reflecting optics housed at the proximal end of the light guide body for reflecting light from the guiding optics across the corneal contour through the light guide body. An ophthalmic topographer 100 with a light guide is also disclosed. A method for determining topography is also disclosed.SELECTED DRAWING: Figure 1

Description

Detailed Description of the Invention

[0001] [Technical field] The present invention relates to an ophthalmic imaging method, device, and system. More particularly, the present invention relates to an ophthalmic imaging method, device, and system including a multi-function light guide and a sclera measurement system. [Background Art] A corneal topographer measures the shape of the anterior corneal surface by capturing the corneal reflection of a known illuminated target pattern imaged into the eye as one or more Meyer lenses, typically a series of concentric illuminated rings separated by black opaque rings known as the Placido system, and analyzing this information starting from the known location of the corneal apex. A separate system is required to determine the distance from a known reference position in the imaging system to the corneal apex of the object being measured.

[0002] Known corneal topographers direct light across the contour of the cornea and generate an image of that contour on an imaging sensor via one or more mirrors and lens systems. This contour imaging system allows for the measurement of the corneal apex position while simultaneously obtaining an image of the target reflection.

[0003] Corneal and scleral mapping has been performed using Scheimpflug topography and other projection-type topography systems, and more recently, optical coherence tomography (OCT). With the Scheimpflug technique, the high-intensity light applied to the retina typically results in scleral clouding. Another drawback of the Scheimpflug system is the high cost of the equipment and the long acquisition time, which reduces accuracy and requires complex alignment methods. Using the limbus as a reference for light intensity, applying low-intensity light to the sclera and high-intensity light to the retina, has also been investigated. Projection systems and OCT can lack accuracy in the critical central corneal region, making them uneconomical for many users in this field.

[0004] To meet the growing demands of the marketplace, alternatives and improvements to corneal topographers and devices are needed that map the cornea and sclera and efficiently add additional diagnostic capabilities to the topographer.

[0005] The reference herein to any prior art is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge. [Summary of the Invention] The present invention is directed to ophthalmic imaging methods, devices and systems.

[0006] In one broad form, the invention is directed to an ophthalmic imaging method, apparatus, and system with a multi-function light guide.

[0007] In another broad form, the invention relates to a light guide portion of an ophthalmic topography that illuminates the eye. In yet another broad form, the invention relates to a light guide or cone portion of an ophthalmic topography that illuminates the eye and transmits and captures light.

[0008] In a first aspect, which need not be the only, nor indeed the most widespread, form, the present invention provides a light guide for an ophthalmic topographer, the light guide comprising: a light guide body comprising a reference object; a topography illumination source that illuminates the light guide body and the reference object, the illuminated light guide body directing light for illumination of the eye being measured; It is equipped with:

[0009] The illuminated light guide body according to the first aspect may also guide a reference object onto the ocular surface. The reference object guided onto the ocular surface may comprise a projected reference object or a Meyer.

[0010] The light guide of the first aspect further comprises: guidance optics housed within the proximal end of the light guide body to guide light from the light guide body across the corneal contour of the eye; and a reflective optical system housed in the proximal end of the light guide body, for reflecting light from the guidance optical system that has traversed the corneal contour back through the light guide body.

[0011] The reflective optics may direct the light to one or more capture systems comprising at least one imaging sensor, wherein the one or more capture systems and / or the at least one imaging sensor may be external to the light guide body.

[0012] In a second aspect, the present invention provides an ophthalmic topographer, the ophthalmic topographer comprising: a light guide body comprising a reference object; a topography illumination source for illuminating the light guide body and the reference object, the illuminated light guide body directing light for illumination of the eye to be measured; and an imaging system that images the reference object projected onto the ocular surface through a central channel within the light guide body.

[0013] In a third aspect, the present invention provides an ophthalmic topographer, the ophthalmic topographer comprising: a light guide body comprising a reference object; a topography illumination source for illuminating the light guide body and the reference object, the illuminated light guide body directing light for illumination of the eye to be measured; an imaging system that images a reference object projected onto the ocular surface through a central channel within the light guide body; guidance optics housed within the proximal end of the light guide body to guide light from the light guide body across the corneal contour of the eye; and a reflecting optical system housed in the proximal end of the light guide body, which reflects light from the guidance optical system that has traversed the corneal contour back through the light guide body.

[0014] The imaging system according to any one of the above aspects may comprise one or more lenses. The imaging system may direct light onto one or more capture systems.

[0015] The reflective optics according to any one of the above embodiments may reflect light for capture onto at least one imaging sensor.

[0016] In a fourth aspect, the present invention relates to a light guide for an ophthalmic topographer, the light guide comprising: A light guide body comprising a reference object, the light guide body directing light towards the reference object.

[0017] The light guide unit according to the fourth aspect may further comprise a topographical illumination light source that illuminates the light guide body and the reference object, and the illuminated light guide body guides light for illuminating the eye to be measured.

[0018] The light guide body according to any one of the above aspects may further comprise a generally symmetrical shape and / or a curved shape at the proximal end. The curved shape may be symmetrical and comprise opposing convex and concave portions so that a wide analytical range of the eye can be achieved by bringing the eye closer to the reference object. The convex portions may house the guidance optics and the reflecting optics. The convex and / or concave portions may be located at opposing points on the light guide body at the proximal end. The convex and / or concave portions may form a scalloped edge.

[0019] According to any one of the above aspects, at least a portion of the guiding optical system and at least a portion of the reflecting optical system may be disposed on opposite sides of the light guide body. In one embodiment, the guiding optical system is located on the left side of the operator, and the reflecting optical system is located on the right side of the operator. In other embodiments, the guiding optical system is located on the right side, above, or below the operator, and in each case, the reflecting optical system is located on the left side, below, or above the operator.

[0020] According to any one of the above-described embodiments, the guiding optical system and the reflecting optical system reflect the light at approximately right angles, and the propagation direction vectors of both of them intersect the axis of the central path at right angles.

[0021] According to any one of the above-described aspects, the light guide body may include a housing for the guiding optical system and a housing for the reflecting optical system, and the housing for the guiding optical system and the housing for the reflecting optical system may be located within respective convex portions that face each other.

[0022] The topographer according to any one of the above aspects may further include one or more capture systems. The one or more capture systems may include at least one imaging sensor, such as a charge-coupled device (CCD) image sensor or a complementary metal-oxide-semiconductor (CMOS) image sensor. The one or more capture systems may include a topography capture system and a contour capture system. The topography capture system may be used in topography using a reference object. The contour capture system may be used in ocular contour analysis using light guided by a reflective optical system. In another embodiment, the one or more capture systems include at least one imaging sensor that performs both topography and ocular contour analysis.

[0023] The ophthalmic topographer according to any one of the above aspects comprises: It may further comprise one or more optical systems for imaging the eye.

[0024] One or more optical systems may be positioned in the optical path for imaging the eye.

[0025] In embodiments where the one or more optical systems include two or more optical systems, the topographer may further include a positioner for selectively positioning each of the optical systems included in the two or more optical systems in the optical path. Each of the two or more optical systems may include an interchangeable optical system in the optical path for imaging the eye.

[0026] The positioner may include a rotating disk on which each of the two or more interchangeable optical systems may be positioned. The rotating disk may include one or more indexing positions for precisely positioning each of the two or more optical systems. The positioner may include a backlash-free positioner. The positioner may include one or more teeth. The rotating disk may include a gear. The positioner may include one or more actuators, such as a motor.

[0027] The rotating disk may include one or more fenestrations for a central topographical system.

[0028] In one embodiment of any one of the above aspects, the topographer includes an illumination array including a topography illumination source and an external optical illumination source. The topographer illumination source may include a distributed light source. The distributed light source and the external optical illumination source may be resolvable or distinguishable. The distributed light source and the external optical illumination source may emit light at wavelengths sufficiently different so as to avoid interference within their respective imaging paths.

[0029] 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 have a distinct narrow band. Each of the plurality of LEDs may produce white light. The plurality of LEDs may, in certain embodiments, comprise an array configured as two or more rings of LEDs. The two or more rings of LEDs may be provided on a printed circuit board.

[0030] The external optical illumination source may emit infrared light. The external optical illumination source may comprise a point light source. In one embodiment, the external optical illumination source is an LED.

[0031] In yet another embodiment of any one of the above aspects, a portion of the light path of the distributed light source and a portion of the light path of the external optical illumination source illuminate the ocular surface.

[0032] The topography illumination source and / or the contour optical illumination source may be located at the distal end of the light guide body.

[0033] 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 disc 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 located along the length of the inner 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 portions. The reference object may be painted or disposed on the light guide body. The painting or other technique may consist of applying only the opaque annuli.

[0034] In another embodiment of any one of the above aspects, the light guide body may include a plurality of segments, each segment having a respective transmission coefficient. The transmission coefficient may be selected to provide uniform illumination along the length of the reference object. Each segment may include any number of transparent and opaque annuli. Each light guide segment may include a light-isolating exterior surface or cover. In one embodiment, one segment may be colored to provide a visual target. In another embodiment, one segment or the light guide body includes a colored filter to provide a visual target. The colored segment or colored filter may be green. The colored filter may include a polymer film in the light path. The visual target or target segment may be located at a distal end of the light guide body. The visual target or target segment may transmit colored light. The light guide body may include 2, 3, 4, 5, 6, 7, 8, 9, or 10 segments. In one embodiment, the light guide body includes three segments. The number of segments may be selected to provide proper illumination.

[0035] In yet another embodiment of any one of the above aspects, the light guide body may comprise an optical medium having a transmission coefficient for light propagation different from that of air.

[0036] In another embodiment of any one of the above aspects, the light guide body is generally conical or toroidal. The generally conical shape may comprise a frusto-conical shape. The conical or toroidal shape may comprise an internal passage. The outer surface may comprise a curved or toroidal shape, and the internal passage may comprise a generally conical shape.

[0037] In yet another embodiment of any one of the above aspects, the light guide body is illuminated with selective colors determined by the light emitted by the illumination array. The light emitted by the illumination array may comprise white, red, green, blue, or infrared light. The visual indication of the modality may comprise light pulses for the selected colors or different brightness or intensity for the selected colors. The light pulses may vary in frequency, modulation, or duration. The brightness or intensity may vary with the modality.

[0038] In yet another embodiment of any one of the above aspects, the guiding optic and the reflecting optic are positioned at substantially opposite points on the light guide body.

[0039] The guidance optics may include one or more prisms positioned between the light source and the exposed eye. The prisms may include diffusing prisms.

[0040] The reflective optics may include one or more mirrors.

[0041] In another embodiment, the guiding optics may comprise a mirror and the reflecting optics may comprise a prism.

[0042] In another embodiment of any one of the above aspects, the light guide body comprises a transparent medium, which may comprise another optically homogeneous transparent medium, which may be comprised of an acrylic resin such as polymethylmethacrylate (PMMA).

[0043] In yet another embodiment of any one of the above aspects, the light guided by the reflective optic is incident on an external imaging system located at a distal end of the light guide body.

[0044] In another embodiment of any one of the above aspects, the external imaging system includes one or more of a focusing lens system and an optical filter that transmits only light from the external optical illumination source.

[0045] In yet another embodiment of any one of the above aspects, the external imaging system focuses the directed light onto one or more capture systems, the directed and focused light comprising distance information from a reference point on the observed eye.

[0046] In yet another embodiment of any one of the above aspects, the external imaging system focuses an external surface of the eye onto one or more capture systems.

[0047] The inner and outer surfaces of the light guide body may be polished to achieve a desired reflectivity compared to the residual scattering of the light source's propagating light.

[0048] In yet another embodiment of any one of the above aspects, a portion of the contour measurement light path is contained within the light guide body. The contour measurement light path, and the internal contour measurement light path, may comprise a guidance optic and a reflection optic. The guidance optic directs light across the contour of the eye toward the reflection optic. The reflection optic directs light to a focusing optic and / or one or more capture systems.

[0049] In another embodiment of any one of the above aspects, the light from the topographic illumination source , following two or more light paths through the light guide body. The two or more light paths may comprise two or more of light rays that are completely outcoupled out of the light guide body, light rays that are partially outcoupled out of the light guide body and partially entering the eye, and light rays that are entirely entering the eye. In embodiments where the exterior surface of the light guide body is painted or coated, there may be no light rays that are completely outcoupled out of the light guide body. Light rays that enter the eye may then traverse the central path and enter one or more capture systems.

[0050] According to any one of the above-described embodiments, the reflective optics and guidance optics for imaging the contour of the eye are included in the contour measurement system.

[0051] In yet another embodiment of any of the above aspects, the light guide body includes a reference object and a profilometry system, and the light guide body provides the optical input necessary to image the topography of the corneal surface.

[0052] In yet another embodiment of any one of the above aspects, the light guide body comprises at least a portion of a central topographic system comprising the light guide body, a topographic illumination source, a reference object, and a topographic imaging system, and the central topographic system may further comprise one or more capture systems.

[0053] According to any one of the above-described embodiments, the ophthalmic topographer may comprise a corneal topographer. According to this embodiment, the ocular surface may comprise a corneal surface, the ocular contour may comprise a corneal contour, the ocular illumination may comprise a corneal illumination, and the ocular analysis area may comprise a corneal analysis area.

[0054] According to any one of the above aspects, the topographer may further include a scleral measurement device. The scleral measurement device may further include one or more scleral projection systems. Each of the one or more scleral projection systems may include a scleral projection light source and a scleral reference object.

[0055] Each scleral reference object may include at least one diaphragm with one or more apertures. The one or more apertures may be located within an aperture pattern. The one or more apertures may include a scleral aperture pattern and, optionally, a corneal aperture pattern. When imaging onto the eye or at least one imaging sensor, the scleral aperture pattern may be imaged as one or more scleral positioners, and the corneal aperture pattern may be imaged as a corneal scatter image.

[0056] 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 lenses.

[0057] One or more scleral projection systems may be symmetrically mounted on the topographer. Symmetrically mounted scleral projection systems may include scleral projection systems mounted on either side of the topographer. In one embodiment, scleral projection systems are located 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 the aperture pattern to be projected onto different portions of the ocular surface.

[0058] The scleral aperture pattern illuminated by the scleral projection light source may be imaged on the projection imaging system and on the scleral portion of the ocular surface, and the corneal aperture pattern illuminated by the projection light source may also be imaged on the projection imaging system and on the cornea.

[0059] The scleral measurement device may further include one or more scleral alignment reference object projectors. The scleral alignment reference object projectors may include a scleral reference light source and a scleral alignment reference object. The scleral reference object may include an alignment reference object light guide, which may optionally be in the form of two or more concentric rings and may include a second Placido disk.

[0060] Light from the scleral reference light source that passes through the scleral alignment reference object may be reflected from the ocular surface and imaged through an imaging system onto one or more image capture systems.

[0061] Light from the scleral reference light source, passing through the scleral registration reference object, and reflected off the ocular surface may generate a scleral image, which may be digitally processed to obtain corneal height information and scleral position with scleral height information.

[0062] The processed scleral image may be used to combine corneal height information from the topographer with the scleral height information to generate a new scleral topography map. The combination may comprise image registration. The registration may utilize one or more of a scleral positioner, a corneal scatter image, and a scleral registration reference image.

[0063] At least one diaphragm may include two or more adjacent alignment apertures through which light from the scleral reference light source can propagate and reach the cornea. In one embodiment, each of the two or more adjacent alignment apertures includes a set of one or more adjacent transparent circular dots. In another embodiment, the adjacent alignment apertures include a set or two or more adjacent alternating transparent and opaque rings concentric with the axis of the central passage, forming a second Placido disk. In certain embodiments, the two or more adjacent apertures include three transparent circular rings. In yet another embodiment, three transparent circular rings may be used as the reference diaphragm, along with alternating transparent and opaque rings.

[0064] The scleral aperture pattern projected onto the ocular surface and the alignment diaphragm may be imaged in the same image on one or more capture systems, and from two such adjacent positioners or dots on the alignment diaphragm, curvature and height information of the reflecting ocular surface can be derived.

[0065] One or more scleral reference object apertures and / or scleral registration apertures may be imaged onto one or more imaging sensors by an imaging system.

[0066] The scleral measurement device may further apply an algorithm to improve the accuracy of the scleral height information by comparing a reference axis of the eye in the scleral image with a reference axis of the eye in the corneal image, which may include rotational information of the eye relative to the axis of the central tract or between the eye and the central tract.

[0067] In one embodiment, the light guide body and the topographic illumination source may form a corneal reference object, which in a preferred embodiment includes both the corneal reference object projected by the light guide body and the topographic illumination source onto the vertex, and a corneal aperture pattern for further corneal reference information.

[0068] In yet another embodiment, the pupil may be captured in both the scleral and corneal images, in which case the captured pupil information may provide information about the reference axis of the eye for further corneal reference information.

[0069] In yet another embodiment, other uniquely identifying scleral features may be used to combine the respective height information for the cornea and sclera.

[0070] In another embodiment, the position of the center of the pupil of the eye relative to the axis of the central tract may be measured to provide reference data for combining the respective height information of the cornea and sclera.

[0071] In a fifth aspect, the present invention provides a method for determining ophthalmic topography, the method comprising: Illuminating a light guide body having a reference object to project the reference object onto the anterior surface of the cornea to be measured, the illuminated light guide body projects light for illuminating the cornea; directing light from the light guide body across the corneal contour using guidance optics housed within the proximal end of the light guide body; using a reflective optic housed in the proximal end of the light guide body to reflect light from the guiding optic that has traversed the corneal contour back through the light guide body; capturing the reflected light with at least one imaging sensor external to the light guide body; A reference object projected onto the corneal surface is captured through a central channel within the light guide body to determine the corneal topography.

[0072] The method of the fifth aspect further comprises: imaging an aperture pattern projected onto the ocular surface by one or more projection lens systems, the aperture pattern projecting at least one scleral reference object and at least one corneal reference object; The scleral height information may be combined with the determined corneal height information.

[0073] According to any one of the above aspects, the light guide may comprise a multi-function light guide. The multi-function may comprise an imaging function comprising delivering light to the eye to image the eye, and an outer optics function comprising imaging the outer contour of the eye. The multi-function and imaging function may also comprise a topography optics function comprising imaging the topography of the eye.

[0074] According to any one of the above aspects, the light guide may include a topography cone.

[0075] According to any one of the above-described aspects, the topographer includes one or more of a housing and a base plate. The topographer may also include an observation object support including one or more of a chin rest and a forehead rest. The topographer may further include an adjustment arm for moving the chin rest up and down. The observation object support may also include a calibration device mounting portion to which a calibration device may be attached for calibrating the topographer. The topographer may also include a manual positioner, such as a joystick. For manual positioning, the base may be moved in two axial directions, i.e., left-right and front-back. The topographer may also be moved up and down, for example, by rotating the joystick. The up and down movement may be achieved by a mounting post that mounts the light guide and other components, such as a topography illumination source, an external imaging system, and a topography imaging system.

[0076] According to any one of the above aspects, the topographer may be connected to a junction box by a topographer cable, and the junction box may be connected to a computer by a computer cable and to a power supply.

[0077] According to any one of the above aspects, the topographer further comprises: The device may include a printed circuit board used to communicate with the computer and / or the device itself. The printed circuit board may be located on a mounting post.

[0078] According to any one of the above aspects, the topographer may also include an external illuminator. The external illuminator may provide light for the interchangeable optics. The external illuminator may include symmetrically mounted light sources. The symmetrically mounted light sources may be located on either side of the light guide, i.e., a symmetrically mounted left light source and a symmetrically mounted right light source. The light sources may be any suitable light source, such as an LED.

[0079] The housing may be a protective enclosure that encloses one or more of the base, the vertical mounting post, at least a portion of the light guide body, the external illuminator, and portions of the scleral measurement device.

[0080] Further aspects and / or features of the present invention will become apparent from the following detailed description.

[0081] In order that the present invention may be readily understood and put into practical effect, reference will now be made to various embodiments of the invention with reference to the accompanying drawings, in which like reference numerals refer to the same elements, and in which the drawings are provided by way of example only. [Brief explanation of the drawings]

[0082] [Figure 1] 1A and 1B are schematic diagrams showing one embodiment of a corneal topographer according to the present invention, with Fig. 1A being a perspective view of the topographer and Fig. 1B being an enlarged view of the cone and cone housing. [Figure 2] 2A and 2B are schematic diagrams showing a cross section of one embodiment of a topographer of the present invention. [Figure 3]3A, 3B, 3C and 3D are schematic diagrams illustrating an embodiment of a positioner for positioning a lens system. [Figure 4] 4A and 4B are schematic diagrams illustrating a positioner according to another embodiment of the present invention. [Figure 5] FIG. 5 is a schematic diagram showing a cross section and optical paths of a conventional device for acquiring corneal contour data. [Figure 6] FIG. 6 is a schematic diagram showing another cross-sectional view and optical path of an apparatus for capturing scleral data according to an embodiment of the present invention. [Figure 7] Figures 7A, 7B, 7C, and 7D show an embodiment of an external image (left) and an embodiment of a corneal image (right) (Figure 7A), a depiction of an eye displaying an image of a reference object (Figure 7B), a depiction of an eye photographed with illumination provided by an external illuminator (Figure 7C), a depiction of an eye wearing a contact lens visualized using fluorescein (Figure 7D), and a depiction of an eye showing the meibomian glands (Figure 7E), respectively. [Figure 8] 8A and 8B are schematic diagrams showing cross-sectional views depicting the optical path for corneal topography (FIG. 8A) and corneal contour imaging (FIG. 8B) according to one embodiment of the present invention. [Figure 9] FIG. 9 is a schematic diagram showing a cross-sectional view depicting the optical path for corneal topography and corneal contour imaging with additional external illumination, according to one embodiment of the present invention. [Figure 10] FIG. 10 is another schematic diagram showing a cross-sectional view depicting the optical path of corneal and scleral topography according to an embodiment of the present invention. [Figure 11] 11A and 11B are schematic diagrams illustrating optical paths for image alignment according to one embodiment of the present invention. [Figure 12] 12A and 12B are schematic diagrams illustrating a reference object guided for image alignment according to one embodiment of the present invention. [Figure 13] FIG. 13 is a schematic diagram showing a front view of a topographer according to one embodiment of the present invention. [Figure 14]14A and 14B show a commercial embodiment of a light guide and topographer according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0083] [Detailed Description of the Invention] A recipient skilled in the art will appreciate that the elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the relative dimensions of some of the elements in the figures may be distorted to help facilitate a better understanding of embodiments of the present invention.

[0084] Embodiments of the present invention relate to improved light guides for ophthalmic topography and improved ophthalmic topographers. Those skilled in the art will readily appreciate that light guides such as those used for topography are also referred to as "cones" because such light guides are generally conical in shape. The light guides of the present invention have an inner surface that is generally conical, but an outer surface that is not conical. In consideration of conventions and terminology used in the art, the terms light guide and cone may be used interchangeably herein.

[0085] The inventors have surprisingly discovered that by integrating a reference object within the light-emitting corneal topography light guide, the reference object can be part of the light guide body and imaging system. This is a significant advantage because it allows the light guide body to be smaller, more cost-effective, and perform the light guiding function with the light guide body, allowing for additional imaging modes and improved corneal topography performance. Another advantage of one embodiment of the present invention is the ability to provide external optics within the light guide body.

[0086] In another embodiment, the present invention provides multi-functional topography by providing a backlash-free interchangeable lens system. The advantage of interchangeable optical means is that each individual lens can be used for each lens design, improving overall quality.

[0087] Additionally, the ophthalmic topographer of the present invention provides, for the first time, the capability and method for scleral topography, which can be combined with additional scleral topography data while maintaining high-quality corneal topography. This allows for improved and higher quality contact lens fitting. Furthermore, the use of fluorescein is no longer required to obtain corneal and scleral topography information, which is a significant advantage for the user and beneficial to subject comfort compared to the prior art.

[0088] As used herein, "optical system" refers to one or more lenses or other imaging elements, mirrors, prisms, spectral optical filters, and / or apertures that direct, observe, analyze, record, and / or capture light. It should be understood that a particular optical system may be configured with various arrangements of one or more lenses or other imaging elements, mirrors, prisms, spectral optical filters, and / or apertures and still perform the same function. For example, if a particular optical system is described herein as including one or more prisms, it should be understood that a different arrangement including one or more lenses or other imaging elements, mirrors, prisms, spectral optical filters, and / or apertures may be used in place of the prisms.

[0089] As used herein, "imaging system" refers to a particular type of optical system that produces a real or virtual image of an object.

[0090] As used herein, a "mire" is a reference object's The image of the pattern projected by the curved surface of the cornea is used in calculating the corneal topography.

[0091] It will become apparent from the following description that the light guide or cone of the present invention is a multi-function light guide or cone. As used herein, "multi-function light guide or cone" refers to a light guide or cone that performs more than one optical function. In one embodiment, the multi-function light guide body guides light and light onto the eye and images the light imaged on the eye onto an imaging sensor, and further includes an external optics system that images the contours of the eye.

[0092] Broadly, one embodiment of the present invention relates to a cone or light guide body that provides a reference object for a topographer.

[0093] In another embodiment, the present invention relates to a light guide or cone unit comprising a reference object, an external optics for imaging the external shape of the eye, and a topography optics for imaging the corneal surface with the illuminated reference object 103 imaged on the eye as a Meyer onto an imaging sensor.

[0094] As described below, in one embodiment, the present invention provides interchangeable optics, allowing for the performance of more than one operating modality or imaging function.

[0095] One embodiment of a topographer 100 according to the present invention is shown in Figure 1. The topographer 100 includes a topographical light guide or cone 101 housed within a housing 121. It is rigidly supported by a base plate 120. A subject support 122, including a chin rest 117 and a forehead rest 118, provides a stable viewing platform. An adjustment arm 119 is also provided for raising and lowering the chin rest. This vertical adjustment allows heads of various sizes to be accurately aligned so that the height of the eye 106 is aligned with the optical axis of the topographer 100.

[0096] Topographer 100 is connected to junction box 160 (not shown) by topographer cable 214. Junction box 160 is in turn connected to conventional computer 161 (not shown) by computer cable 162 (not shown) which plugs into a universal serial bus (USB) port, and to power supply 163 (not shown) by power cable 164 (not shown).

[0097] The observation object support 122 also includes a calibration device mounting portion 165 (not shown) to which a calibration device 166 (not shown) can be attached for calibrating the topographer 100 .

[0098] Topographer 100 also includes a manual positioner 167 that includes a joystick 168 that can be used to move base 169 in two axes, left-right and front-to-back. Additionally, up-down movement can be achieved by rotating joystick 168. This allows topographer 100 to be accurately and conveniently aligned with subject's eye 106. Up-down movement is achieved by a mounting post 169 that mounts light guide 101 and other components, such as light guide illumination array 155, external imaging system 112, and topography imaging system 123.

[0099] As will be described in more detail below, topographer 100 also includes an external illuminator 207 that provides additional light for topography and additional eye imaging functions. External illuminator 207 includes light sources 208 mounted symmetrically on either side of light guide 101. The light source 208 may be any suitable light source, such as an LED.

[0100] As will be further described below, some embodiments of the topographer 100 optionally include a scleral measurement device 400. The scleral measurement device 400 includes one or more scleral projection systems 401 and scleral reference objects 402, as shown in Figures 10 and 11A. The scleral measurement device may further include one or more scleral alignment reference object projectors 404.

[0101] Additionally, as described in more detail below, the imaging system 123 also includes one or more actuators 307 (not shown), such as motors, that rotate the turntable 302 to a predetermined alignment position within the optical path of the imaging system.

[0102] Also located on mounting post 169 is a printed circuit board 170 (not shown) that is used to control topographer 100 and communicate with computer 161. As shown in Figures 1A and 1B, all of the internal components are housed within housing 121, which forms a protective enclosure surrounding base 169 and vertical mounting post 170. Light guide body 102 is also partially housed within housing 121.

[0103] 1B shows a portion of light guide 100 and external imaging system 112. Light guide 100 includes a light guide body 102 that includes at least a portion of reference object 103, and illuminates light guide body 102 to image the topographical annulus or ring as Meyer 126.

[0104] The light guide body 102 is comprised of a transparent medium 104. In the embodiment shown in Figure 2, the transparent medium 104 is comprised of polymethylmethacrylate (PMMA). Based on the teachings herein, one of ordinary skill in the art can readily select any other suitable transparent medium. The transparent medium 104 may also comprise another optically homogeneous transparent medium.

[0105] The light guide body 102 is configured with a generally torus-shaped or conical outer surface 142 and a generally conical inner surface 141. In the embodiment shown in the figures, the generally torus-shaped or conical shape is a torus or frusto-cone shape with a central passageway 124. The diameter of the cone 101 decreases along its length from the distal end 115 to the proximal end 109. By torus-shaped or conical, we mean that the diameter at the distal end is larger than the diameter at the proximal end, and the circumferences of the concentric transparent and opaque annuli 128 and opaque annuli along the length of the light guide body 102 decrease from the distal end 115 to the proximal end 109.

[0106] The light guide body 102 has dimensions that are just right to fit the shape of a human face, with a central passage opening diameter of less than 35 mm, an outer diameter of the light guide body 102 of less than 70 mm, and a length of the light guide body 102 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 450 mm.

[0107] In another embodiment, light guide body 102 is generally symmetrical and includes a curved shape 125 (not shown) at proximal end 109. Curved shape 125 is comprised of symmetrically opposed convex portions 145 (not shown) and concave portions 146 (not shown). Convex portions 145 house at least a portion of guidance optics 108 and at least a portion of reflecting optics 111. Convex portions 145 are located at opposing points on proximal end 109. Concave portions 146 are also located at opposing points on proximal end 109. The convex portions and concave portions may form a scalloped edge.

[0108] In another embodiment of any one of the above aspects, at least a portion of the guiding optics and at least a portion of the reflecting optics are located opposite each other on the proximal end of the light guide body, and notably, the guiding optics guides light perpendicular to the optical axis.

[0109] Light guide 101 is attached to topographer 100 via mounting flange 147 (not shown). The torus or cone shape of light guide body 102, which houses central passage 124, allows eye 106 to be exposed to reference object 130 on inner surface 141.

[0110] FIG. 1B shows a front perspective view of a portion of topographer 100 with an enlarged view of the area with light guide 101 and reference object 103 visible through central passage 124.

[0111] As shown in the perspective view of Figure 1B and the cross-sectional view of Figure 2A, the reference object 130 comprises a plurality of annulus or rings, alternating transparent annulus 128 and opaque annulus 129 (represented as dashed lines in the cross-sectional view of Figure 2A). In the embodiment shown, the reference object 130 comprises a plurality of transparent annulus 128 positioned along its axial length on its inner surface 141, each bordered on either side by an opaque annulus 129. The distal annulus 128, 129 is bordered only by the corresponding non-distal annulus 129, 128.

[0112] Illuminating the light guide 101 illuminates the transparent annuli 128, forming virtual images of concentric rings generated by the curvature of the anterior corneal surface 148 as the Meyer rings 126. The imaging system 123 may be used to image the Meyer rings 126 generated by the anterior corneal surface 148 and resulting from the transparent annuli 128, and the topography of the cornea 107 may be determined by analyzing the imaged Meyer rings. In this regard, and in this embodiment, the reference object 103 may be referred to as a Placido disc.

[0113] Inner surface 141 faces central passage 124. Inner surface 141 and outer surface 142 of light guide body 102 may be polished to function as reflective or refractive optical surfaces.

[0114] Transparent annulus 128 is integral with light guide body 102. In the embodiment shown, reference object 103, or more precisely, opaque annulus 129, is painted or applied onto light guide body 102. In another embodiment, the painting or other technique may consist of painting opaque annulus 129 and transparent annulus 128. In yet another embodiment, reference object 103 may comprise an overlay 149 (not shown) comprising a transparent sheet 151 having opaque annulus 134 thereon. In this embodiment, opaque annulus 129 may be printed onto sheet 151. As a result, overlay 149 is positioned within central channel 124 such that printed opaque annulus 129 extends along the length of channel 124.

[0115] 1A and 1B, the reference object 103 includes 30 transparent annuli 128. Given the teachings herein, one of ordinary skill in the art can readily select other suitable numbers of reference objects or other suitable Meyer-formed shapes. For example, the reference object 103 may include 5-50, 10-40, or 20-35 transparent annuli or other Meyer-formed shapes.

[0116] 2A and 8A also show that the light guide body 102 may be made up of multiple light guide segments 130 to provide uniform illumination of the annulus 126. In the embodiment shown in FIGS. 2A and 8A, the light guide body 102 is made up of three segments 130i, 130ii, and 130iii. Each segment 130 is connected to a respective transparent annulus 126. Each segment 130 has a matching coupling efficiency to provide even illumination along the length of the object 103. Each segment 130 may have any number of transparent annuli 128 and opaque annuli 129.

[0117] In other embodiments, the light guide body 102 may include 1, 2, 4, 5, 6, 7, 8, 9, 10, or more than 10 segments 130. The number of segments 130 may be selected to provide adequate illumination.

[0118] In the embodiment shown, each segment 130 provides a coupling efficiency to produce an evenly illuminated ring-shaped image on at least one imaging sensor 1116 .

[0119] It is important that the light guide body 102 provide a higher coupling efficiency than the free space illumination of the topography illumination sources 105, including the distributed illumination sources 200 and the contoured optical illumination sources 201.

[0120] As shown in FIG. 8A, each light guide segment 130 and some or all of the outer surface 142 may include a light isolation cover 131 to prevent light from leaking to other light guide segments or to prevent or reduce light from being outcoupled outside the light guide body 102.

[0121] Segment 130(i) comprises a target segment, which may be colored or may comprise a visual indicia to provide a target for gaze by eye 106 looking through path 124. In the embodiment shown, target segment 130(i) is colored green, although this cannot be displayed in black and white. Target segment 130(i) is shown at the distal end of light guide body 102. The other segments 130(i),(ii) may all be of the same light-transmitting material but with different dimensions and coupling efficiencies than 130(i), and may preferably be transparent.

[0122] Figure 2A illustrates the corneal topography components according to one embodiment of the present invention, while Figure 2B illustrates the contour imaging components according to one embodiment of the present invention. Further explanation is provided by Figures 8A and 8B, which show the optical paths of the central topography optics 150 and contour measurement system 172, respectively.

[0123] As shown in both Figures 2A and 2B, illumination of topographer 100 is provided by light guide illumination array 155, which includes topography illumination sources 105 (Figure 2A) and outer optical illumination sources 201 (Figure 2B). Light guide body 102 is illuminated by topography illumination sources 105. Notably, topography illumination sources 105 and outer optical illumination sources 201 are separable. Topography illumination sources 105 and outer optical illumination sources 201 may emit light at wavelengths sufficiently different to avoid image interference on at least one imaging sensor 116.

[0124] The topography illumination source 105 illuminates the reference object 103, at least the transparent annulus 128. That is, the topography illumination source 105 illuminates the light guide body 102 to provide light that illuminates the cornea 107 and projects the reference object 103 onto the anterior corneal surface 148.

[0125] The topography illumination source 105 comprises a distributed illumination source 200, and therefore 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 mounted on a printed circuit board (PCB) 203. , arranged in two or more concentric rings of LEDs 153. Although no corresponding drawing is provided, in the embodiment shown, the topography illumination source 105 comprises an outer ring 105(a) and an inner ring 105(b).

[0126] 8A illustrates three optical paths for light emitted by topographic illumination source 105, which is comprised of LED 153. Some light has optical paths such as topographic path 206a, which is completely outcoupled from light guide body 102 through outer surface 142. Other light travels along topographic path 206b, where a portion of the light is outcoupled from outer surface 142 to the light guide body 102, and a portion of the light travels along topographic path 206c, where the light reflects off outer surface 142 toward inner surface 141, enters eye 106 before crossing central path 124, and then strikes at least one imaging sensor 116. In other words, light within light guide body 102 may split at outer surface 142, with some light being refracted and directed toward the surrounding environment. Optical path 206d shows a ray of light that does not pass through outer surface 142 but instead turns toward inner surface 141, where it enters eye 106 before crossing central path 124, entering central imaging system 123, and impinging on at least one imaging sensor 116 to generate corneal image 204. That is, Mayer 126 is imaged on imaging sensor 116.

[0127] 2B, the contour optical illumination source 201 is shown to include a contour point light source 202 in the form of a single LED that emits infrared light. Light from the point light source 202 traverses the light guide body 202, is directed by the guidance optics across the corneal contour 110, is received by the reflection optics 111 and directed to the imaging system 112, and is directed to the capture system 113 and at least one imaging sensor 116, which generates and captures the contour image 205.

[0128] Guiding optics 108 are shown to include a mirror 133, and reflecting optics 111 are shown to include a prism 143. In other embodiments, this configuration is reversed, with guiding optics 108 including a prism and reflecting optics 111 including a mirror.

[0129] The contour imaging system 112 is shown to include a mirror 133 and other components to direct the light propagation direction vector 134 towards the capture system 113. From Figures 2A and 2B, it can be seen that imaging is performed using the capture system 113, which is shown to include at least one imaging sensor 116. In other embodiments, the capture system 113 includes more than one imaging sensor, which may be in the form of a topography imaging sensor 173 (not shown) and a contour imaging sensor 152 (not shown).

[0130] 2A also shows that the relative position of the light guide body 201 and the eye 106 may be moved, for example, using a positioner 167. This is advantageous because it allows for convenient positioning of the eye 106 with respect to each of the optical systems 300a, 300b, 300c, and 300d configured in the interchangeable optical system 300. In the embodiment shown in FIGS. 3A, 3B, 3C, and 3D, the interchangeable optical system 300 is disposed on a positioner 301, which is in the form of a turntable 302 that can be rotated in both directions to precisely align each of the optical systems 300a, 300b, 300c, and 300d in the central path with one or more capture systems 113.

[0131] As shown in FIG. 3A, the rotating disk 302 includes a fenestration 308 relative to the axis of the central passage 144 of the central topography system 150 .

[0132] The wheel 302 rotates in both directions, clockwise and counterclockwise, as shown by the arrows in FIG. 3A. It may also rotate in the opposite direction.

[0133] The wheel 302 has an index position 303 that engages one or more teeth 309, which in the embodiment shown in Figures 3A, 3B, 3C and 3D consists of only one tooth, but may also be located on a pivoting lever 305 that acts as a spring 304.

[0134] The turntable 302 includes one or more index positions 303 for precisely positioning each of the two optical systems. In the embodiment shown in Figures 3A, 3B, 3C, and 3D, the interchangeable optical system 300 includes four optical systems 300a, 300b, 300c, and 300d and four corresponding index positions 303a, 303b, 303c, and 303d. By selecting the appropriate index position 303a, 303b, 303c, and 303d to engage one or more teeth 309, each optical system 300a, 300b, 300c, and 300d may be precisely aligned with the central channel 124 for imaging of the eye 106.

[0135] Figure 3A shows one or more teeth 309 not yet engaged with the wheel 302 and about to switch between two index positions 303. Figure 3B shows one or more teeth 309 just engaged when further rotation of the wheel 302 causes the pivot lever 305 to spring back into engagement with the wheel 302.

[0136] FIG. 3D shows another embodiment of the positioner 301, where instead of using a pivoting lever 305, a sliding element 306 is used.

[0137] Although not shown, the positioner 301 further includes one or more actuators 307 in the form of motors 421 to effect the rotation.

[0138] 4 shows another embodiment of the positioner 301, which includes a motor 421 that drives a transmission belt 422 to effect rotation of the wheel 302. In another embodiment, the wheel 302 includes gears.

[0139] In the embodiment shown in Figure 3D, the interchangeable optical system 300 includes six optical systems, but in other embodiments, it may include two, three, five, seven, eight, nine, ten, or more optical systems.

[0140] Positioner 301 is a backlash-free positioner, which is advantageous in that it provides precise positioning and prevents or at least reduces unwanted movement.

[0141] Advantageously, the light guide body 102 is illuminated in different colors determined by the light emitted by the illumination array 155. The light emitted by the illumination array 155 may be configured in different distinguishable colors that indicate the modality in use, such as the central topography system 150, the profilometry system 172, or a corresponding one of the interchangeable optical systems 300.

[0142] From the above, one skilled in the art will appreciate that the visible light component used to propagate light to illuminate the eye 106 can be split on its outer surface and outcoupled from the light guide body 102 into the surrounding area where it can be visible to the user or patient. The outcoupled light may also be used to illuminate the eye 106 in addition to other illumination means for imaging the eye 106 or the area surrounding the eye 106.

[0143] The light that is outcoupled and visible to the user or the subject under examination can contain information about the operating status of the topographer 100 and other information. , which may be presented in the form of color, as in the preferred embodiment, but may also include other light modulations such as light pulses or brightness changes.

[0144] The light guide body 102 also provides a portion of the propagation of the light path for illuminating the corneal contour 110 and capturing a corneal image 204 onto at least one imaging sensor 116 .

[0145] Figure 7A shows a contour image 205 (left) and a corneal image 204 (right). Figure 7A also shows that the contour data effectively comprises a contour outline 137 and a vertex position 138. A reference position 139 may be provided to determine the position of the eye 106 relative to the reference object 130 or central imaging system 123. These images 204, 205 can be reconstructed using data captured from one or more capture systems 113.

[0146] Figures 7B, 7C, 7D, and 7E are examples of information and images that may be obtained using interchangeable optical system 300. Figure 7B shows an anterior segment image. Figure 7C shows a corneal image. Figure 7D shows an image with a contact lens, and Figure 7E shows a meibomian gland image. Figures 7B, 7C, 7D, and 7E may be obtained using, for example, optical systems 300a, 300b, 300c, and 300d, respectively.

[0147] Another significant advantage of the interchangeable optical systems 300 is that each optical system 300a, 300b, 300c, 300d, etc. is a complete system, not requiring any other imaging elements, and generally remains separate from the topographer 100, or elements are shared among the interchangeable optical systems 300a, 300b, 300c, 300d, etc. This allows for more than one imaging function to be performed.

[0148] A schematic diagram of a prior art device for imaging the corneal contour is shown in Figure 5. The cross-sectional view shows that the prior art contour optics and their respective light paths are external, or mostly external, to the light guide body.

[0149] This is in contrast to the profilometry system 172 and profilometry optical path 206 shown in FIG. 8B, which traverses the light guide body 102.

[0150] 8B shows the contour measurement optical path 206 of light emitted by the contour optical illumination source 201. The light passes through the transparent medium 104 and through the guidance optics 108 and the reflecting optics 111 mounted at opposite points on the proximal end 109 of the light guide body 102. The guidance optics 108 includes a mirror 143 that directs the transmitted light across the corneal contour 110 along the portion of the contour measurement optical path 206 between the mirror 143 and the prism 143 included in the reflecting optics 111.

[0151] The reflecting optics 111 reflects light that has been guided from the guidance optics 108 and that has traversed the corneal contour 110 and directs the light through the light guide body 102 to the contour imaging system 112 and onto one or more capture systems 113.

[0152] At least a portion of the light captured by the guidance optics 108 is incident on a reflecting optics 111 located adjacent the distal end 110 of the cone 100. The contour image 206 contains information about the distance from a reference point on the observed eye 190. The distance information is used in conjunction with information contained in the corneal image to obtain corneal curvature information. The distance information is derived by measuring the contour 137 of the contour image 205 and comparing the vertex position 138 to a reference position on the contour image 205.

[0153] As shown in FIG. 2B, the external imaging system 112 also captures a small portion of the external surface of the eye 106. The external imaging system 112 may include one or more focusing lenses 135 for focusing onto at least one imaging sensor 116. The external imaging system 112 may be designed to compensate for the optical path length through the light guide body 102.

[0154] Also shown in FIG. 2B is that the external imaging system 112 further includes an optical filter 254 that passes only or nearly only infrared light from the external optical illumination light source 201.

[0155] The surface of the light guide body 102 used in the propagation of light for external imaging of the eye is approximately perpendicular to the light propagation direction vector 134. That is, the guiding optical system and the reflecting optical system reflect the light at approximately right angles, and the propagation direction vectors of both systems intersect the axis of the central path at right angles.

[0156] It may be desirable to provide additional light to the central topography system 105. Figure 6 shows a schematic cross-section of the topographer 100, showing the relative position of the external illuminator 207 to the light guide body.

[0157] The external illuminator 207 is located outside the plane of the light guide body 102, while the centrally or internally located illumination array 155, topography illumination source, and contour imaging illumination source 201 are in the same plane as the light guide body 102 and are therefore positionally distinct from them.

[0158] The exterior illuminator 207 includes a light source 208 that provides additional illumination as shown in Figures 6 and 9. In the embodiment shown, the light source 208 comprises an LED.

[0159] 10, 11A, and 11B, the topographer 100 may further include a scleral measurement device 400. The scleral measurement device 400 includes one or more scleral projection systems 401, each including a scleral projection light source 406 and a scleral reference object 402.

[0160] The scleral reference object 402 includes at least one diaphragm 415 with 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 onto the eye 106 or at least one imaging sensor 116, the scleral aperture pattern 405 may be imaged as one or more scleral positioners 418, and the corneal aperture pattern 414 may be imaged as a corneal scatter image 419. As shown in FIG. 11A, the corneal scatter image 419 is through the cornea, and thus the measurements are through the eye in volumetric scatter units.

[0161] The one or more scleral projection systems 401 further include a scleral projection imaging system 403, which is shown to include one or more lenses.

[0162] 10 , the one or more scleral projection systems 401 comprise two symmetrically positioned scleral projection systems 401, one mounted on each side of the topographer 100. The symmetrically mounted scleral projection systems 401 may comprise a scleral projection system 401 mounted on either side of the topographer 100. In one embodiment, the scleral projection systems 401 are located 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 the aperture patterns 405, 414 to be projected onto different portions of the ocular surface.

[0163] A scleral aperture pattern 405 illuminated by the scleral projection light source 406 may be imaged on the scleral projection imaging system 403 and on the scleral portion of the ocular surface. A corneal aperture pattern 414 illuminated by the projection light source 406 may also be imaged on the projection imaging system 403 and on the cornea 107.

[0164] The scleral measurement device 400 further includes one or more scleral alignment reference object projectors 404 that include a scleral reference light source 408 and a scleral alignment reference object 407. The scleral alignment reference object 407 may include an alignment reference object light guide 409, which may optionally be in the form of two or more concentric rings or may include a second Placido disk. Light from the scleral reference light source 408 that passes through the scleral alignment reference object 407 may be reflected from the ocular surface and imaged onto one or more image capture systems 113 via an imaging system 123.

[0165] Light emitted from the scleral reference light source 408, passing through the scleral registration reference object 407, and then reflected from the ocular surface produces a scleral image 410. The scleral image 410 is digitally processed to provide corneal height information and scleral position with scleral height information. Readers familiar with corneal topography will recognize that the height and curvature information of the eye 106 are conjugate and contain the same information. The scleral height and curvature information may be converted into one another by applying commonly known mathematical techniques.

[0166] The processed scleral image 410 may be used to combine the corneal height information from the topographer 100 with the scleral height information to generate a new scleral topography map. This combination may comprise image registration. Registration may utilize one or more of a scleral positioner 418, a corneal scatter image 419, and a scleral registration reference image 420.

[0167] The alignment diaphragm 423 includes two or more adjacent alignment apertures 423a through which light from the scleral reference light source 408 can propagate and reach the cornea 107. In the embodiment shown, the two or more adjacent alignment apertures 423a each include a set of one or more adjacent transparent circular dots. In other embodiments, the adjacent alignment apertures 423a include a set or two or more adjacent alternating transparent and opaque rings concentric with the axis of the central channel 124, forming a second Placido disk 416. As shown in FIG. 13 , the two or more adjacent alignment apertures 423a include three transparent circular rings. In yet another embodiment, circular rings may be used as the reference diaphragm, and alternating circular rings may be used.

[0168] The scleral aperture pattern 405 projected onto the ocular surface and the alignment diaphragm 423 may be imaged in the same image onto one or more capture systems 113. From two such adjacent rings or dots on the alignment diaphragm 423, curvature and height information of the reflecting ocular surface can be derived.

[0169] The scleral measurement device 400 may further apply an algorithm to improve the accuracy of the scleral height information by comparing the reference axis of the eye in the scleral image 410 with the reference axis of the eye in the corneal image 204. This reference axis may include rotational information of the eye 106 relative to the axis of the central tract 124 or between the eye 106 and the central tract 122.

[0170] In one embodiment, the light guide body and the topographic illumination source may form a corneal reference object, which in a preferred embodiment includes both the corneal reference object projected by the light guide body and the topographic illumination source onto the vertex, and a corneal aperture pattern for further corneal reference information.

[0171] Advantageously, the pupil 413 may be captured in both the sclera image 410 and the cornea image 204, in which case the captured pupil information may provide information about the reference axis of the eye. Additionally or alternatively, other uniquely identifiable scleral features may be used to combine the respective height information of the cornea and sclera.

[0172] Additionally, the position of the center of the pupil of the eye 106 relative to the axis of the central tract 124 may be measured to provide reference data for combining the respective height information of the cornea and sclera.

[0173] Using the scleral measurement device 400 as part of the topographer 100 allows for the scleral data to be combined with corneal topography data. This is advantageous because it does not rely on scattered images, but rather uses reflection from the cornea. Additionally, the relative pupil positions of the two eyes may be measured to provide reference data for image alignment.

[0174] An advantage of the present invention is that the diameter at the proximal end 113 can be reduced because illumination is not occurring external to the light guide body 102. This allows the corneal surface 148 to be brought closer to the light guide body 102, thereby allowing a larger portion of the cornea to be analyzed.

[0175] Another advantage of the present invention is that the illumination does not create shadows that affect the light distribution. The present invention also significantly reduces the number of components required for illumination and the manufacturing complexity.

[0176] As used herein, the words "comprise" and "comprising" or similar words are intended to mean inclusion is not exclusive. For example, a device that comprises certain listed elements may contain not only those elements, but may also contain other elements that are not listed.

[0177] Throughout this specification, the objective has been to describe the invention without limiting it to any particular embodiment or collection of features. Those skilled in the relevant art will be able to realize variations from the particular embodiments that will still fall within the scope of the invention.

Claims

1. A light guide for an ophthalmic topographer, comprising: a light guide body comprising a reference object; a topography illumination source that illuminates the light guide body and the reference object, the illuminated light guide body directing light for illumination of the eye to be measured; guidance optics housed within the proximal end of the light guide body to guide light from the light guide body across a corneal contour of the eye; a reflective optical system housed in the proximal end of the light guide body, which reflects light from the guidance optical system that has traversed the corneal contour and passes it through the light guide body.

2. The light guide of claim 1 , wherein the illuminated light guide body also guides the reference object onto the eye surface.

3. 1. An ophthalmic topographer, comprising: a light guide body comprising a reference object; a topography illumination source that illuminates the light guide body and the reference object, the illuminated light guide body directing light for illumination of the eye being measured; and an imaging system that images the reference object projected onto the ocular surface through a central channel within the light guide body.

4. 1. An ophthalmic topographer, comprising: a light guide body comprising a reference object; a topography illumination source that illuminates the light guide body and the reference object, the illuminated light guide body directing light for illumination of the eye being measured; and an imaging system that images the reference object projected onto the eye surface through a central channel within the light guide body; guidance optics contained within the proximal end of the light guide body that guides light from the light guide body across a corneal contour of the eye; a reflective optical system housed in the proximal end of the light guide body, the reflective optical system reflecting light from the guiding optical system that has traversed the corneal contour back through the light guide body.

5. 10. A light guide or ophthalmic topographer according to any one of the preceding claims, wherein the reflective optics reflects light for capture onto at least one imaging sensor.

6. A light guide for an ophthalmic topographer, comprising:

1. A light guide for an ophthalmic topographer, comprising: a light guide body comprising a reference object, the light guide body directing light towards the reference object.

7. 7. The light guide of claim 6, further comprising a topography illumination source that illuminates the light guide body and the reference object, the illuminated light guide body directing light for illumination of an eye to be measured.

8. 10. The light guide or ophthalmic topographer of any one of the preceding claims, wherein the light guide body further comprises a generally symmetrical shape and / or comprises a curved shape at the proximal end.

9. 10. A light guide or ophthalmic topographer according to any one of the preceding claims, wherein at least a portion of the guiding optics and at least a portion of the reflecting optics are respectively disposed on opposite sides of the light guide body.

10. 10. The ophthalmic topographer of claim 2, further comprising one or more capture systems.

11. 10. An ophthalmic topographer according to any one of the preceding claims, further comprising one or more optical systems for imaging the eye.

12. The ophthalmic topographer of claim 11, wherein when the one or more optical systems comprise two or more optical systems, the topographer may further comprise a positioner that selectively positions each of the optical systems comprised in the two or more optical systems within the optical path.

13. 10. An ophthalmic topographer according to any one of the preceding claims, wherein the topographer comprises an illumination array comprising the topography illumination source and an external optical illumination source.

14. 10. A light guide or ophthalmic topographer according to any one of the preceding claims, wherein the light guide body comprises an optical medium having a transmission coefficient for light propagation different from that of air.

15. 10. A light guide or ophthalmic topographer according to any one of the preceding claims, wherein the light guide body is illuminated in selective colors determined by the light emitted by the illumination array.

16. 10. A light guide or ophthalmic topographer according to any one of the preceding claims, wherein part of the profile measurement light path is provided within the light guide body.

17. 10. A light guide or ophthalmic topographer according to any one of the preceding claims, wherein light from the topography illumination source follows more than one optical path through the light guide body.

18. 10. The ophthalmic topographer of any one of the preceding claims, wherein the topographer further comprises a scleral measurement device.

19. 20. The ophthalmic topographer of claim 18, further comprising one or more scleral projection systems.

20. 20. The ophthalmic topographer of claim 19, wherein each of the one or more scleral projection systems comprises a scleral projection light source and a scleral reference object.

21. 21. The ophthalmic topographer of claim 20, wherein each scleral reference object comprises at least one diaphragm with one or more apertures.

22. 22. The ophthalmic topographer of claim 21, wherein when imaged onto the eye or the at least one imaging sensor, the scleral aperture pattern may be imaged as one or more scleral positioners and the corneal aperture pattern may be imaged as a corneal scatter image.

23. 23. The ophthalmic topographer of any one of claims 18 to 22, wherein the one or more scleral projection systems are mounted symmetrically on the topographer.

24. 24. The ophthalmic topographer of claim 23, wherein the symmetrically mounted scleral projection systems comprise scleral projection systems mounted on either side of the topographer.

25. 25. The ophthalmic topographer of any one of claims 18 to 24, wherein the scleral measurement device further comprises one or more scleral alignment reference object projectors.

26. 26. The ophthalmic topographer of claim 18, wherein light emitted from the scleral reference light source, passed through the scleral alignment reference object, and reflected off the ocular surface produces a scleral image.

27. 27. The ophthalmic topographer of claim 26, wherein the scleral image is digitally processed to obtain corneal height information and scleral position with scleral height information.

28. 28. The ophthalmic topographer of claim 27, wherein the processed scleral image is used to combine corneal height information from the topographer with the scleral height information to generate a new scleral topography map.

29. 30. The ophthalmic topographer of claim 28, wherein said combining comprises image registration.

30. 1. A method for determining an ophthalmic topography, comprising: illuminating a light guide body having a reference object to project the reference object onto the anterior surface of the cornea to be measured, the illuminated light guide body projecting light for illuminating the cornea; directing light from the light guide body across the corneal contour using guidance optics housed within the proximal end of the light guide body; using a reflective optic housed in the proximal end of the light guide body, reflecting light from the guidance optic that has traversed the corneal contour through the light guide body; capturing the reflected light with the at least one imaging sensor external to the light guide body; The method further comprises capturing the reference object projected onto the corneal surface through a central channel within the light guide body to determine a corneal topography.

31. moreover, imaging an aperture pattern projected onto the ocular surface by one or more projection lens systems, the aperture pattern projecting at least one scleral reference object and at least one corneal reference object; 31. The method of claim 30, wherein the scleral height information is combined with the determined corneal height information.

Images