Cross-Reference to Related Applications

[0001] The present application claims the benefit of U.S. Provisional Patent Application No. 63/021 ,810, filed May 8, 2020, the entirety of which is hereby incorporated by reference.

FIELD

[0002] The present disclosure relates to an eye measurement system for measuring characteristics of an eye.

BACKGROUND

[0003] Eye care providers use a number of devices employing a variety of techniques to assess the health of the eye of a patient. Such devices often assess particular eye characteristics and compare them to known values to assess for the onset of certain conditions as well as to assist in the assessment of overall eye health.

[0004] One characteristic of the eye which is often measured is intraocular pressure (IOP). Determination of IOP can assist in the early detection of conditions such glaucoma. IOP in a patient is detected in a number of ways, but one common way is to use a non-contact tonometer, which applies a small puff of air onto the cornea with the amount of deflection of the cornea being measured through optical means. The amount of deflection can then be compared to reference values for IOP and the IOP determined for assessment for overall eye health. Such an approach is effective, but is not necessarily particularly accurate, and can require fairly significant air pressures for the puff of air which can cause discomfort to the patient.

[0005] Another characteristic of the eye which is often determined is the topography of its cornea. This is usually done by reflecting an image comprising a series of concentric circular or elliptical rings (known as Placedo rings) onto the surface of the corneal tear film and analyzing the reflected image to determine variations in ring position in the reflective image and thereby determine the topography of the cornea. The image is usually generated by back lighting a disc or cone with concentric masked and translucent regions to create the image on the eye. By determining the topography of the cornea, contact lenses may be fit, determination is to be made about surgeries that a patient may need, certain corneal ectasias can be detected or, again, to anticipate potential reductions in the health of the eye from other disorders.

[0006] Yet a further characteristic of the eye which is often determined is tear breakup time. By determining the evaporation rate of tears it can be possible to determine the onset of conditions such as dry eye syndrome, as well as determine the overall health of the Meibomian and lacrimal glands and the eye itself. Determination of tear breakup time has normally been performed by assessing evaporation rate by applying a fluorescent dye (such as fluorescein), illuminating the eye and looking for dark areas within the dye which signify higher rates of evaporation and therefore a potential issue with eye health.

[0007] As will be appreciated, whilst there are benefits in taking all three of the above sets of measurements, each requires its own techniques and equipment and therefore is a need to simplify the testing equipment which obtains data on these characteristics whilst maintaining and improving accuracy of measurement and simplifying the testing procedure. The present disclosure seeks to achieve these aims.

SUMMARY

[0008] According to one embodiment of the present disclosure, there is provided a system for measuring the intraocular pressure of the eye, the system comprising: a projector for projecting an image of Placedo rings on to the cornea of an eye; a source of pressurized air for applying a puff of air onto the cornea; a light receptor for receiving an image of the Placedo rings reflected from the cornea; and a control unit for receiving an output from the light receptor, processing the output, and determining the intraocular pressure of the eye based on the processed output.

[0009] The control unit may determine the intraocular pressure by determining the amount of deflection on the cornea generated by the puff of air, the amount of deflection being determined by the distortion of the rings in the reflected image received by the image receptor. [0010] The source of pressurized air may be integrated with the projector and/or the light receptor, in which case the source of pressurized air may be arranged to dispense air through one of the projector at an angle offset from the axis of projection of the projector or along the axis of projection of the projector from a port adjacent to the light receptor.

[0011] According to another embodiment of the present disclosure, a system for measuring the tear break up time of an eye, the system includes a projector for projecting an image of Placedo rings on to the cornea of an eye; a light receptor for receiving a series of time separated images of the Placedo rings reflected from the cornea; and a control unit for receiving an output from the light receptor, and processing the output to provide an indication of tear break up time for the eye based on the processed output.

[0012] The control unit may provide an indication of tear break up time by analyzing the series of images to determine changes in the smoothness and integrity of ring edges over time and comparing those changes with reference data.

[0013] According to yet another embodiment, a system for measuring both the intraocular pressure and tear break up time of the eye includes a projector for projecting an image of Placedo rings on to the cornea of an eye; a source of pressurized air for applying a puff of air onto the cornea; a light receptor for receiving a series images of the Placedo rings reflected from the cornea over time; and a control unit for receiving an output from the light receptor, processing the output, and determining the intraocular pressure and tear break up time of the eye based on the processed output

[0014] As will be appreciated from the above, the present disclosure provides a system which can improve significantly the accuracy of measurement of eye characteristics such as IOP and tear break up time. It also enables the provision of a device which can determine a number of characteristics with a reduced number of components and with the potential for less discomfort for a patient. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Examples of the present disclosure will now be described with reference to the accompanying drawings, in which:

[0016] FIG. 1 schematically depicts a conventional intraocular pressure detection system;

[0017] FIG. 2 is a diagram showing projection of a set of Placedo rings onto the cornea of an eye;

[0018] FIG. 3 schematically depicts a system, according to one or more embodiments of the present disclosure;

[0019] FIG. 4 depicts a diagram showing a projection generated during operation of the system during a tear breakup time analysis, according to one or more embodiments of the present disclosure; and

[0020] FIG. 5a schematically depicts a Placedo ring projection component, according to one or more embodiments shown and described herein; and

[0021] FIG. 5b schematically depicts another embodiments of a Placedo ring projection component, according to one or more embodiments shown and described herein.

DETAILED DESCRIPTION

[0022] Embodiments of the present disclosure are directed to systems for measuring one or more eye characteristics including, but not limited to intraocular pressure, tear break-up time, corneal topography, or the like. For example, in one embodiment a system for measuring intraocular pressure may include a projector , a source of pressurized air, a light receptor, and a control unit. The project may be configured to project an image of Placedo rings on to the cornea of the eye. The source of pressurized air may be configured to apply a puff of air onto the cornea. The light receptor may be configured to receive an image of the Placedo rings reflected from the cornea. The control unit may receive an output from the light receptor, process the output, and determine the intraocular pressure of the eye based on the processed output. As will be described in greater detail below, systems according to the present disclosure may improve the accuracy of measurement of eye characteristics such as intraocular pressure and tear break up time while also enabling the provision of a device which can determine a number of characteristics with a reduced number of components and with the potential for less discomfort for a patient. These and additional embodiments will be described in greater detail below.

[0023] Referring to FIG. 1 , a conventional intraocular pressure (IOP) measurement device is shown measuring the IOP of an eye by applying a puff of air 2 via an air source 3 to the cornea 1 of an eye . When the puff is applied the cornea 1 is deflected, changing its profile. An electro optical light source 4 illuminates the eye and the deflection is detected by an electro optical detector 5, which detects a change in position of the light 6 reflected by the cornea 1. This change in position can be referenced with standard data to determine the IOP as the amount of deflection is correlated to IOP

[0024] FIG. 2 shows the cornea 1 during a separate conventional eye characteristic measurement where a series of concentric rings 10 (known in this field as Placedo rings) are projected onto the cornea 1 and the reflected image analyzed. Distortion in the reflected ring image can be used to determine the topography of the cornea 1 , which in turn is useful in assessing eye health. Flowever, using separate systems to provide the various measurements may be cumbersome, tedious, and/or costly.

[0025] Referring now to FIG. 1 , a system of the present disclosure is schematically depicted. The system generally includes a central sensing component 17. The sensing component 17 is communicatively coupled to a control unit 18 which receives an output from the sensing component 17 and which in turn is connected to a reference database 19.

[0026] For example, the control unit 18 may include a processor and a non-transitory computer readable memory. The processor may include an type of an integrated circuit, a microchip, a computer, or any other computing device. The non-transitory computer readable memory may be communicatively coupled (e.g., over a wired or wireless communication path) to the processor. The non-transitory computer readable memory may comprise RAM, ROM, flash memories, hard drives, or any non-transitory memory device capable of storing machine-readable instructions such that the machine-readable instructions can be accessed and executed by the processor. The machine-readable instruction set may comprise logic or algorithm(s) written in any programming language of any generation (e.g., 1 GL, 2GL, 3GL, 4GL, or 5GL) such as, for example, machine language that may be directly executed by the processor, or assembly language, object-oriented programming (OOP), scripting languages, microcode, etc., that may be compiled or assembled into machine readable instructions and stored in the non-transitory computer readable memory. Alternatively, the machine- readable instruction set may be written in a hardware description language (HDL), such as logic implemented via either a field-programmable gate array (FPGA) configuration or an application-specific integrated circuit (ASIC), or their equivalents. Accordingly, the functionality described herein may be implemented in any conventional computer programming language, as pre-programmed hardware elements, or as a combination of hardware and software components.

[0027] The sensing component 17 is communicatively coupled to the control unit 18 and has an optical source 14 (e.g., a light source) disposed and may further include a mask 20, 21 , as will be described later, and is arranged such that light from the optical source 14 passes through the mask 20, 21 to generate an image that is reflected off of the corneal tear film of an eye. The image include set of Placedo rings 10. Reflected light 6 passes back from the cornea 1 into the sensing component 17 where it is received by an optical receptor 15. The optical receptor 15 may be any device configured to output a signal indicative of a characteristic of the image. For example, the optical receptor may be a camera, a scanner, or the like. The output of the optical receptor 15 is provided to the control unit 18, where it may be processed be the processor via execution of machine-readable instructions to determine such characteristics as IOP, corneal topography, tear break-up time, or the like.

[0028] Where the system is configured to determine tear break up time, a series of time-lapse sequential images may be captured by the sensing component 17 and received by the control unit 18. The control unit 18 may then carry out edge analysis instructions stored on the non-transitory computer readable memory on the received images within a certain region 11 of the images, though other regions are contemplated and possible. By comparing the edge analysis of the series of images an indication of variations in the received images over time can be determined by the control unit 18, that variation then being referenced to information in the database 19 (e.g., stored on the non-transitory computer readable memory, or a remote database such as stored on a remote server). That information provides reference indication showing variations in changes in images with respect to reference tear break up times such that a tear break up time for the individual patient being assessed can be determined and output as necessary by control unit 18. For example, in some embodiments, the control unit 18 may have a display for displaying outputs to a user.

[0029] Where the system of the present disclosure has been employed to determine IOP, then the sensing element 17 further comprises a source of air 12 (e.g., a cylinder, a diaphragm, or the like) which can provide a puff of air 12 onto the surface of the cornea. The source of air 12 may be communicatively coupled to the control unit 18 which may selectively operate emission of the puff of air 12. For example, when the puff of air 12 is applied to the cornea 1 and an image is reflected off of the corneal tear film 1 , the received reflected light 6 generates an image in the sensing component 17 which is transmitted to the control unit 18. Distortion of the received image from a series of circles or ellipses can be determined and that distortion compared to reference data stored in the database 19 to determine the amount of deflection of the cornea 1 and therefore the IOP for the patient being assessed. The employment of Placedo rings 10 to determine the deflection provides a higher degree of accuracy compared to prior art arrangements, which means that the strength of the puff of air 12 can be reduced, improving patient comfort as well as improving accuracy of the measurement.

[0030] It will be appreciated that the system of the present disclosure also enables the receipt of reflected images from the reflected light 6 that could be provided to the control unit 18 for analysis of the topography of the cornea 1 to assess other aspects of the health of the eye of the patient being assessed. For example, image data received from the sensing component 17 may allow the control unit, using edge processing or the like, may determine corneal topography characteristics.

[0031] It will also be appreciated that the system can be configured such that it can perform two or three of the above eye assessments with a single device by simple configuration of the control unit 18 and provision of appropriate reference data in the database 19. All this can be done with a reduced number of components compared to previous testing, and in a device of reduced size and improved accuracy.

[0032] FIGS. 5a and 5b show two embodiments of the sensing component 17 of the system. The sensing component 17 may generally include a light source 14 (or projector), a light or optical receptor 15, and one or more sources of air 12, such as described above. The light source 14 may include a conical mask formed from a series of mask elements 21 (e.g., rings) and intervening translucent regions 20 within a light source 14. The rings may be formed from any material which substantially blocks transmission of light. When the light source 14 is illuminated, passage of light through the translucent elements 20 and blocking of the light by mask elements 21 generates an image on a cornea 1 that represents the Placedo rings 10. Light 6 (depicted in FIG. 3) reflected back from the cornea 1 passes through to light receptor 15 which can provide the output for the sensing component 17. In this example two sources of air 12 are provided which have a port (e.g., a tube) that passes through a sidewall of the light source 14 to allow a puff of air 12 to be generated and applied to the cornea 1 as appropriate. The ports may be positioned at an angle offset from the axis of projection of the projector.

[0033] FIG. 5b schematically depicts an embodiment of the sensing component 17 with similar components to those of FIG. 5a. Flowever, in the present embodiment the flow path for the puff of air is provided around or directly adjacent the optical receptor 15 to direct the air directly onto the cornea 1 . In this embodiment, projection of air may be along the axis of projection of the light source. Such configuration has the potential for more accurate application of air and greater displacement of the cornea 1 for the same volume of air when compared to FIG. 5a. It also has the potential to reduce optical defects that might be generated by the sources of air 12 in FIG. 5a caused by passage through light source 14.

[0034] As will be appreciated by a person skilled in the art, in the configurations of either FIG. 5a and 5b, the conical mask configuration that is provided to generate the image of the Placedo rings 10 may be replaced by a simple planar disk which is backlighted, with the light receptor 15 positioned at the center of the planar disk and with a series of concentric masks spreading out from the center to generate the required image when the disk is backlit to provide a light source 14. Such a configuration may, in some circumstances, be more compact in a direction perpendicular to the axis of illumination which may have benefits to certain applications.

[0035] As will be appreciated from the above, the present disclosure provides a system which is compact, with a reduced overall footprint, while providing multiple measurements for a patient’s eye with an improved level of accuracy.

[0036] While particular embodiments have been illustrated and described herein, it should be understood that various other changes and modifications may be made without departing from the spirit and scope of the claimed subject matter. Moreover, although various aspects of the claimed subject matter have been described herein, such aspects need not be utilized in combination. It is therefore intended that the appended claims cover all such changes and modifications that are within the scope of the claimed subject matter.