Patent Application
20240350007
The present disclosure relates to systems and methods for measuring intraocular pressure of the eye, and more particularly relates to the use of improved systems, devices, and methods for using tonography to make such measurements.
Tonometry is the measurement of intraocular pressure (IOP), which is the balance between the amount of fluid produced within the eye and the rate at which it exits the eye, termed “outflow facility.” A method of measuring “outflow facility,” in turn, can be referred to as tonography, where tonography is a procedure of recording tonometry measurement changes over a duration of time (e.g., IOP) with a device called a tonometer. IOP monitoring and treatment is key to diagnosing and managing eye conditions. More particularly, elevated IOP is the greatest risk factor for the development of glaucoma. Glaucoma is a progressive disease and accurate IOP measurements can be integral in its early detection and diagnosis. Once diagnosed, glaucoma management focuses on monitoring and lowering of IOP with medical and surgical interventions. Some clinical decisions are made based on very small changes in IOP. Thus, it is critical to be able to produce repeatable IOP measurements so that providers can have confidence in measured IOP changes.
The current clinical gold standard for measuring IOP is Goldmann applanation tonometry (GAT). While devices that use GAT have their benefits, there are also many drawbacks. This method relies strongly on human observation and is therefore prone to variability. GAT is subjective, prone to biased readings, and can have poor repeatability. Additionally, this method typically requires the use of expensive, bulky, often immobile equipment, which thus limits measurement of a patient's IOP to a clinical setting, and more particularly certain rooms where the equipment is already located. Other methods for measuring IOP exist, but they also have significant drawbacks. The existing limitations of other tonometers include high variability and poor agreement with GAT. For many methods, measurements require the application of topical anesthetic, therefore limiting measurements to the clinical setting. The use of anesthetics also necessarily requires additional steps and exposure to additional materials to perform the procedures. The various drawbacks of these systems result in a smaller number of measurements for a given patient than is desirable, which in turn limits physician insight into day-to-day IOP variation that could otherwise be relied upon to better inform the physician to provide a more targeted treatment.
Existing tonography methods also have significant drawbacks. For example, Schiøtz tonography and pneumatonography are poorly tolerated due at least due to long testing duration and suffering from poor repeatability. Fluorophotometry is another way to assess outflow facility. However, among other issues, obtaining a measurement using this technique can take several hours. There are also invasive techniques for measuring outflow facility, but any such techniques suffer from a number of problems, such as infection and risk of trauma to the eye due to need insertion. Further, ocular rigidity, pseudofacility, and uveoscleral outflow facility can confound the measurement.
Accordingly, there is a need for improved systems and methods to obtain objective intraocular pressure (IOP) measurements that are consistent, accurate, non-invasive, easy to use, and/or portable, as well as capable of generating tonographic measurements and/or outflow facility measurements.
The Summary is provided to introduce a selection of concepts that are further described below in the Detailed Description. This Summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.
The present disclosure describes devices and methods used to measure intraocular pressure in the eye of a subject by using fixed force applanation tonometry. The present disclosure has benefits over current devices and systems because it is handheld, portable, and automated. The device applies a constant fixed force to the surface of the eye and an image capturing device obtains images of the area of the eye flattened under the force. A controller than uses an image-processing algorithm to automatically calculate the intraocular pressure from the resulting applanation images.
One exemplary embodiment of an applanation device includes a housing, an applanator, an image-capturing system, and a controller. The housing forms an internal cavity, and has an applanator access opening formed in an outer wall of the housing. The applanator access opening process access between the internal cavity and an outside environment. The applanator is disposed in the internal cavity of the housing. The applanator has a distal tip that is configured to pass into and through the applanator access opening to apply a force to an eye of a subject located in the outside environment. The distal tip can include one or more fiducial markings on it, for example to provide reference points for determining a reference distance upon which the controller can rely upon to calculate intraocular pressure.
The housing can provide for the applanation device to be a portable, handheld applanation device. In at least some embodiments, the device can include a power source disposed in the internal cavity of the housing. The power source can provide power to the image-capturing system and/or the controller. The image-capturing system can be disposed in the internal cavity of the housing and can be configured to capture a plurality of applanation images of the eye. The controller can also be configured to receive the plurality of applanation images captured by the image-capturing system and determine intraocular pressure in the eye based on the capture plurality of applanation images. The controller can be configured to be disposed inside the housing, or alternatively, it can be configured to be disposed outside of the housing. In the latter instance, the controller can be provided as part of a computer and/or a smartphone.
The force applied to the eye by the distal tip of the applanator can be a constant force for a duration of time during which the plurality of applanation images of the eye are captured. The distal tip can be conically-shaped and conformable. In at least some embodiments, the distal tip can be monolithic. The image-capturing system can include at least one camera. In some embodiments, the applanation device can also include at least one illumination source. The illumination source(s) can be disposed in the housing and can be configured to supply light to the distal tip.
The applanation device can include a lever arm and a counterweight. The lever arm can have a first end, a second end, and a fulcrum disposed between the two ends. The counterweight can be disposed on a second side of the fulcrum, more proximate to the second end than the first end, while the distal tip can be disposed on a first side of the fulcrum, more proximate to the first end than the second end. In at least some such embodiments, the applanation device can also include a constant force spring that can be coupled to the lever arm. The constant force spring can be configured such that the force applied to the eye by the distal tip of the applanator is a constant force.
The applanation device can include a sensor(s). The sensor(s) can be configured to measure the force applied by the distal tip to the eye and communicate the measured force to the controller. Alternatively, or additionally, the applanation device can include a force-adjustment mechanism, which in at least some embodiments, can be associated with the housing. The force-adjustment mechanism can be in communication with the applanator, and further, it can be configured to change an amount of the force being applied to the eye. The controller can be further configured to be in communication with the applanator such that the controller can direct a change in an amount of the force being applied to the eye.
The controller can be configured to identify an outer reference circle that is representative of a circumference of the distal tip and an inner circle that is representative of an applanation mire such that a surface area of the applanation mire can be determined. Accordingly, the intraocular pressure of the eye can be determined based on the determined surface area of the applanation mire and an amount of the force applied to the eye. In at least some embodiments the controller can be configured to remove from consideration one or more images of the plurality of applanation images captured by the image-capturing system to speed up processing time to determine intraocular pressure in the eye. This removal can be based on, for example: (a) one or more identified contours of the image(s); and/or one or more starburst ellipses approximated from the image(s). In at least some embodiments where such removal is based at least one the one or more identified contours of the image(s), parameters of the contours on which such removal can be based include at least one of: (a) a contour area; (b) a contour size; (c) a contour location; and/or (d) an eccentricity of the contour after fit to an ellipse.
The applanation device of any of the instances provided above, or elsewhere herein, can be configured to be used both when the subject is in a supine position and when the subject is in an upright position.
One exemplary method of measuring at least one of intraocular pressure in an eye or an outflow facility of an eye includes placing a distal tip of an applanator on a surface of an eye of a subject to cause a fixed force to be applied to the eye, capturing a plurality of applanation images of the eye while the fixed force is applied to the eye, and operating a processor to use information from the applanation images and the fixed force to determine at least one of intraocular pressure in the ye or an outflow facility of the eye.
In at least some embodiments, the applanator can include a lever arm and a counterweight. The lever arm can have a first end, a second end, and a fulcrum disposed between the two ends. The counterweight can be on a second side of the fulcrum, more proximate to the second end than the first end, while the distal tip can be disposed on a first side of the fulcrum, more proximate to the first end than the second end. The counterweight can supply a counter fixed force to enable application of the fixed force to the eye. The applanator can be disposed within a housing of a portable, handheld applanation device.
The method can include measuring a value of the fixed force and communication that measured value of the fixed force to the processor. The method can also include adjusting a value of the fixed force to a prescribed value. This can include, for example, causing the distal tip to apply the fixed force at a preset value such that the preset value becomes the adjusted value. This can also include, for example, operating one or more controls associated with the applanator to adjust the value of the fixed force across a plurality of values.
In some embodiments the method can include operating at least one of the processor or a separate processor to identify from the plurality of applanation images an outer reference circle that is representative of a circumference of the distal tip of the applanator and an inner circle that is representative of an applanation mire. This can be done to determine a surface area of the applanation mire, which can be information from the applanation images that is used to determine the intraocular pressure in the eye. In some such embodiments, the method can include using one or more fiducial markings on the distal tip of the applanator to provide reference points used in conjunction with the information from the applanation images to determine the intraocular pressure in the eye.
The method can include operating at least one of the processor or a separate processor to remove from consideration one or more images of the plurality of applanation images captured by the image-capturing system to speed up processing time to determine intraocular pressure in the eye. This can include removing the image(s) from consideration based on, for example: (a) one or more identified contours of the image(s); and/or one or more starburst ellipses approximated from the image(s). In at least some embodiments where such removal is based at least one the one or more identified contours of the image(s), parameters of the contours on which such removal can be based include at least one of: (a) a contour area; (b) a contour size; (c) a contour location; and/or (d) an eccentricity of the contour after fit to an ellipse.
In at least some embodiments, both intraocular pressure in the eye and the outflow facility of the eye are measured during the same procedure. In at least some embodiments, the subject is able to be in either a supine position or an upright position when placing the distal tip of the applanator on the surface of the eye of the subject and when capturing the plurality of applanation images of the eye while the fixed force is applied to the eye.
Any of the features or variations described herein can be applied to any particular aspect or embodiment of the present disclosure in a number of different combinations. The absence of explicit recitation of any particular combination is due solely to avoiding unnecessary length or repetition.
This disclosure will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
Certain exemplary embodiments will now be described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the devices and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments and that the scope of the present disclosure is defined solely by the claims. The features illustrated or described in connection with one exemplary embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present disclosure.
Articles “a” and “an” are used herein to refer to one or to more than one (i.e., at least one) of the grammatical object of the article. By way of example, “an element” means at least one element and can include more than one element. “About” is used to provide flexibility to a numerical range endpoint by providing that a given value may be “slightly above” or “slightly below” the endpoint without affecting the desired result. The use herein of the terms “including,” “comprising,” or “having,” and variations thereof, is meant to encompass the elements listed thereafter and equivalents thereof as well as additional elements. As used herein, “and/or” refers to and encompasses any and all possible combinations of one or more of the associated listed items, as well as the lack of combinations where interpreted in the alternative (“or”).
Moreover, the present disclosure also contemplates that in some embodiments, any feature or combination of features set forth herein can be excluded or omitted. To illustrate, if the specification states that a complex comprises components A, B and C, it is specifically intended that any of A, B, or C, or a combination thereof, can be omitted and disclaimed singularly or in any combination. Similarly, to the extent features or actions are described herein as being a “first feature” or “first action,” or a “second feature” or “second action,” such numerical ordering is generally arbitrary, and thus such numbering can be interchangeable. Moreover, a person skilled in the art will appreciate that not all of the method steps or actions disclosed herein are required, and, in view of the present disclosure, will understand how modifications can be made to each step, the order of the steps, the limitation of certain steps, etc. without departing from the spirit of the present disclosure while still achieving the desired goals.
Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. For example, if a concentration range is stated as approximately in the range of about 1% to about 50%, it is intended that values such as approximately in the range of about 2% to about 40%, approximately in the range of about 10% to about 30%, or approximately in the range of about 1% to about 3%, etc., are expressly enumerated in this specification. These are only examples of what is specifically intended, and all possible combinations of numerical values between and including the lowest value and the highest value enumerated are to be considered to be expressly stated in this disclosure, as are values slightly above and/or slightly below those ranges at least in instances in which the term “about” is used. A number of terms may be used throughout the disclosure interchangeably but will be understood by a person skilled in the art. By way of non-limiting example, the terms “constant” and “fixed” may be used interchangeably when referring to the force applied to the surface of the eye.
Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Additionally, like-numbered components across embodiments generally have similar features unless otherwise stated or a person skilled in the art would appreciate differences based on the present disclosure and his/her knowledge. Accordingly, aspects and features of every embodiment may not be described with respect to each embodiment, but those aspects and features are applicable to the various embodiments unless statements or understandings are to the contrary.
The present disclosure provides for applanation devices, and associated methods, for performing tonometry, and in turn methods of performing tonography, which is for measuring an outflow facility associated with the eye (i.e., the rate at which fluid produced by the eye exists the eye). The devices and methods disclosed provide portable devices for the convenient and easy determination of intraocular pressure (IOP) in an eye. A constant force is applied by a distal tip of an applanator to an eye, enabled by a counterweight disposed on an opposite side of the applanator, and then an imaging capture system is able to record a plurality of images while the constant force is being applied to the eye. A control system, which can be part of the applanation device or in communication with the same (e.g., by way of a smartphone or other computing device, which can run an associated application or “app”), an then operate using an algorithm disclosed herein for determining IOP based at least on information recorded in the captured images and the value of the constant force applied to the eye. The applanation device can be a portable, handheld device, operable by a clinician or physician. It is contemplated that the disclosures provided for herein can also enable embodiments that can be used at home by patients, i.e., outside of a clinical setting.
In the illustrated embodiment, the housing 20 includes a handle portion 22, which can be a location where a user can wrap his or hand around to operate the device 10, and a component portion 24, which can be a location where the various operating components of the device 10 can be disposed. More particularly, as shown in
The housing 20, and thus the handle portion 22 and the component portion 24, can have a variety of shapes, features, and sizes, with designs of the handle portion generally being conducive for easy gripping by a user, and designs of the component portion 24 generally being conducive to house components that enable the device to perform its intended function, i.e., measuring IOP using the techniques and features described herein. For example, the housing 20 can be sized to be portable and handheld, with the handle portion 22 shaped and sized to fit a human hand and the component portion shaped and sized to be a rectangular prism.
The operable components of the applanation device 10 (e.g., the applanator 30, the image-capturing system 50, and, at least in some embodiments, the controller 60) can be disposed, at least partially, in the internal cavity 26. The phrase “at least partially” is appropriate, as described in greater detail below, at least because at least some portion of one or more components (e.g., a distal tip 32 of the applanator 30) can be configured to pass out of the internal cavity 26 and the housing 20 at least during use. More particularly, the housing 20 can include an applanator access opening 28 formed in an outer wall of the housing 20. The applanator access opening 28 provides access between the internal cavity 26 and an outside environment such that a portion of the applanator 30 can pass therethrough to access the outside environment, such as to contact a subject's eye. The “at least partially” phrase may also be applicable to aspects of the image-capturing system 50 and/or the controller 60 as well.
The applanator 30 of the applanation device 10, sometimes referred to as a force-applying mechanism or force applier 30, is illustrated in greater detail in
The distal tip 32 can include a terminal end surface 32s configured to contact a cornea at a surface of an eye of a subject (see
The application of a constant force by the distal tip 32 can be enabled by the constant force mechanism 40 associated with the lever arm 34. In the illustrated embodiment the constant force mechanism 40 is disposed at the fulcrum 36, although a person skilled in the art will appreciate other configurations are possible such that the constant force mechanism 40 can be disposed at other locations along the lever arm 34. The constant force mechanism 40 can be any of a variety of mechanical components known by those skilled in the art for supplying a constant force, including but not limited to various springs.
As shown in
In other embodiments, the constant force can be generated through a variety of mechanisms and means known to those skilled in the art conducive for such use in view of the present disclosures, including but not limited to a torsional spring force (including but not limited to the embodiment illustrated in
Turning back to the configuration of
As shown, two counterweights 38 are disposed at the proximal end 34p of the lever arm 34, though a person skilled in the art will appreciate fewer or more counterweights can be used and can be disposed at other locations along the lever arm 34, typically more proximate to the proximal end 34p than the distal end 34d of the lever arm 34. Different sized and shaped counterweights 38 can be provided. In at least some embodiments, mechanical mechanism can be provided that enable the effect of the counterweights 38 to be adjusted by a user. This can include selectively including or not including a counterweight on the lever arm to provide a force that in turn causes the distal tip 32 to provide a force on the cornea (or other object in the outside environment on which the distal tip 32 contacts) and/or selectively sliding one or more of the counterweights 38 along the lever arm 34. A person skilled in the art, in view of the present disclosures, will understand how the counterweight(s) 38 can be maneuvered with respect to the lever arm 34 to change an amount of force that is in turn supplied by the distal tip 32 and/or able to be maintained by the distal tip 32.
In at least some embodiments, the applanation device 10 can include a force-adjustment mechanism 70, which can be in communication with the applanator 30 and configured to change the amount of force applied to the surface of the eye. The force-adjustment mechanism 70 can include an input interface 72 such as a touch screen (as shown), dial, and/or buttons coupled with and/or disposed on the housing 20 and configured to receive an input of desired magnitude of force from the user. The force-adjustment mechanism 70 can then communicate the desired amount of force to the applanator 30 by a variety of means including mechanically and/or electrically. In a non-limiting exemplary embodiment, the user enters the desired force in the input interface 72 and the force-adjustment mechanism 70 can directly engage with the applanator 30 to apply the desired force to the surface of the eye, via the distal tip 32. By way of example, when the force-adjustment mechanism 70 includes a constant force mechanism 40 like a torsional spring or torsional spring mechanism, adjusting the torsion on the spring can induce a different force to be applied. Adjustment of the force can be achieved, for instance, by adjusting the position, mass, and/or weight of the counterweight(s) 38 and/or adjusting the position and/or location of the constant force mechanism 40, a different force can be supplied. In some embodiments, the controller 60 can act as the force-adjustment mechanism, or as part of the force-adjustment mechanism, such as by providing such communication to alter a force being supplied by the applanator 30, as further described below.
Further, the magnitude of the constant force supplied by the applanator 30 can be tuned to a prescribed level by way of the force-adjustment mechanism 70. In some embodiments, the force-adjustment mechanism 70 can include one or more preset values (e.g., values of force) that can be accessed by a user and/or be programmed by a user. It may be desirable, for example, to have different force levels for patients experiencing extreme eye pressure, such as advanced glaucoma or after glaucoma surgery. In a non-limiting example, the constant force can be set approximately in the range of about two (2) grams to about fifteen (15) grams. As provided for herein, a magnitude or value of the constant force supplied by the applanator 30 can be tuned, for example by adjusting the value to a prescribed value. As the force is adjusted, one or more prescribed values can become the adjusted value, i.e., the value to which the applanator 30 is adjusted to apply. This can also include, for example, operating one or more controls associated with the applanator 30 to adjust the value of the fixed force across a plurality of values. In some embodiments, one or more sensors 74 (see
The applanation device 10 also includes the image-capturing system 50. A person skilled in the art, in view of the present disclosures, will understand suitable components of such a system that can be incorporated into the applanation device 10. In some embodiments, such as the one illustrated with respect to
A controller 60 can also be included as part of the applanation device 10. This can include having the controller 60 disposed within the housing 20 and/or can involve communicating with the applanation device 10. Alternatively, the controller 60 may be considered a separate component that is not part of the applanation device 10. The controller can operate aspects of the algorithm described below with respect to
As shown, the applanation device 10, including components thereof (e.g., the camera 52, the light source 54, the controller 60, portions of the force adjustment mechanism 70, etc.), can be powered by one or more power sources. In the illustrated embodiment, a connected cord or wire, such as a power cord 80, can be provided to deliver power from an outside source, such as AC or DC power source, to the applanation device 10. In other embodiments, one or more batteries (rechargeable or other acceptable battery type for use in such a device) can be provided in the internal cavity 26 of the housing 20 to provide desired power to the various components of the applanation device 10.
While the applanation devices of the present disclosures, e.g., the devices 10, 110, can have a variety of shapes, sizes, and configurations, impacted, at least in part, by the shape, size, and/or configuration of the components, the age, size, and anatomy of the subject, and/or the preferences of the user with respect to the way and type of measurements are being made, a general beneficial feature of the present disclosure is the portability of the applanation devices resulting from the present disclosures. Accordingly, as shown in
The image-capturing system 250 can be substantially aligned with a distal tip 232 of an applanator 230 of the device 210 as shown in
In use, the distal tip 232 of the applanation device 210 extends from the housing 220, is placed on the surface of the eye 4, and it applies a constant, fixed force to the eye 4 to flatten the cornea 2 to define a fixed area. As a result of the present disclosures, the distal tip 232 can be applied to the eye of a subject in the upright or supine positions, and thus the device 210 itself can be used when a subject is in either such position. This is at least because the counterweight(s) and the constant force mechanism can be calibrated so that in a supine position, the device 210 provides a constant force, and then in an upright position, the weight of the counterweights can combine with the force of gravity, thus still allowing the device 210 to provide a constant force.
An illumination source 252, which in this instance is disposed outside of the housing 210, though as provided for elsewhere, it can be disposed in the housing, directs light to the distal tip 232 and onto the eye 4. The image-capturing system 250, substantially aligned with the distal tip 232 of the applanator 230, can capture a plurality of images of the applanation surface 258 while the constant force is applied. In some embodiments the image-capturing device 250 can record a video from which frames can be selected as the images 290. In some embodiments, a fluorescent yellow dye can be applied to the eye 4 prior to the application of the constant force by the distal tip 232. In the exemplary embodiment shown, the illumination source 252 can pass blue LED light towards and/or into the distal tip 232 and onto the dyed applanation surface of the eye 4. The blue hue can combine with the yellow dye to highlight the applanation surface 258 in a green outline, which can be present on the generated images 290. As shown in
The controller 260, as well as other controllers provided for herein, such as the controllers 60, 160, can be operable to receive the plurality of images from the image-capturing device 250, and further, can be configured to operate an image-processing algorithm 270 to process the image data and calculate the IOP of the eye 4. The controller 260 can contain a single processor or a plurality of processors to carry out the methods disclosed herein. As mentioned above, in some embodiments, the controller 260 can act in conjunction with or as part of a force-adjustment mechanism to direct a change in the force applied to the eye 4 by communicating with the applanator 230 of the applanation device 210, such as by mechanical and/or electrical means. For example, it can communicate by sending signals to the applanation device 210 to direct a change in the force applied by the distal tip 232 automatically and/or to an operate to make manual adjustments to the force applied by the distal tip 232. Alternatively, the controller 260 can work in conjunction with a separate force-adjustment mechanism to direct the change in force. The controller 260 can be a computing device such as a smartphone, tablet, laptop, personal computer device, computer, or other similar computing device. An exemplary embodiment of a controller 260 is described below with respect to
The algorithm 270 can begin by having applanation images inputted, as shown at input action 272. The algorithm 270 can be configured to crop each image or frame, as shown at crop action 274, for instance to get rid of dead space on left and/or right edges of the image, isolate the color channels, as shown at isolate action 276, and use Hough Circle Detection to identify the outer edge of the reference circle, as shown at detection action 278. Hough Circle Detection is described in greater detail at https://docs.opencv.org/4.x/dd/dla/group_imgproc_feature.html #ga47849c3be0d0406ad3c a45db65a25d2d, the content of which is incorporated by reference herein in its entirety. In some embodiments, the use of Hough Circle Detection can entail, for every fifth frame, identifying a prism edge using Hough Circle Detection. The image can be further cropped, at crop action 280, based on a last prism edge found, such as the edge of the reference circle.
The contrast of each image can be adjusted, as accounted for at contrast action 282, for example using Contrast Limited Adaptive Histogram Equalization, which is described in greater detail at https://docs.opencv.org/3.4/d6/db6/classcv_1_1CLAHE.html, the content of which is incorporated by reference herein in its entirety. A binary mask can then be created from each image, as shown at mask action 284, for example by thresholding the frame. Further, known image-processing routines can be used to locate contours in each frame, as indicated by finding action 286, including techniques described in greater detail at https://docs.opencv.org/3.4/d3/dc0/group_imgproc_shape.html #ga17ed9f5d79ae97bd4c7cf 18403e1689a, the content of which is incorporated by reference herein in its entirety. After contours are located, a contour evaluation action, as shown by evaluation action 288, can be performed. Any contours that are smaller than a designated minimum area can be removed from consideration, as designated by action 290. As provided for herein, any removal of contours from consideration, or more generally removal of images from the plurality of images captured by the image-capturing system (e.g., the image capturing device 250), can be done to speed up processing time by eliminating contours that are determined to not be applanations.
For each remaining contour, the algorithm 270 can measure the area and centroid of the minimum enclosing circle, as shown by measuring action 292, for example by using the techniques described at https://docs.opencv.org/3.4/d3/dc0/group_imgproc_shape.html #ga8ce13c24081bbc7151e9 326f412190f1, the content of which is incorporated by reference herein in its entirety. A contour size and location evaluation action can occur, as shown by evaluation action 294. If the contour does not meet certain size and/or location requirements (i.e., located inside of the reference circle and/or smaller than the reference circle), the contour can be removed from consideration, as designated again by action 290. The remaining contours can each be fit to an ellipse, as shown by fitting action 296, and eccentricity can be calculated in view of the same. Fitting the contour of an ellipse can be performed using techniques described at https://docs.opencv.org/3.4/d3/dc0/group_imgproc_shape.html #gaf259efaad93098103d6c2 7b9e4900ffa, the content of which is incorporated by reference herein in its entirety. An eccentricity evaluation can be performed as shown by evaluation action 298. If the eccentricity is above a designated maximum limit, the respective contour can be removed from consideration, as designated again by action 290.
The algorithm 270 can then approximate each contour as an ellipse, for example using the starburst method as shown by approximate ellipse action 300 (labeled as starburst method, but other methods of approximating each contour as an ellipse can be possible). More particularly, this can include starting at a distance slightly below an expected ellipse radius and then stepping out radially in evenly-spaced directions (e.g., 20 evenly-spaced directions) until a contour mask is reached. The smallest contour ellipse in each frame can be selected. The ellipse can then be fit to a consecutive set of points (e.g., a consecutive set of 15 points). The best ellipse can then be selected based on parameters such as small size and/or low eccentricity. Evaluation can then be performed to determine whether the identified starburst ellipse is in the right location and is the right size, as shown by evaluation action 302. If not, it can be removed from consideration, as designated once again by action 290.
After analyzing all contours in the frame, if there is more than one eligible contour left, the smallest one can be selected, as shown by selection action 304. Alternatively, if no good contours are identified, a list detailing why each contour failed can be outputted (not shown in flowchart, but stems from evaluation action 302). The selected contour ellipse represents the inner circle or the applanation surface and the area of said ellipse is measured. The IOP can then be calculated, as shown by calculation action 306. The calculation can be based on an area of applanation, and can be added to a buffer of applanations. More particularly, in view of a diameter of the prism edge, typically in millimeters, being known, and a constant force applied by the tonometer also being known, the applanation area in pixels can be converted to a pressure in mmHg. In some embodiments, the IOP calculation can be performed using the Imbert-Fick principle, which states that the IOP equals the force applied divided by the area of the applanation surface. In other embodiments, the algorithm 270 can be configured to calculate the applanation mire diameter using a machine learning and/or deep learning approach. For example, the algorithm 270 can be trained to identify relevant physical features indicative of an applanation mire using a known dataset.
In instances in which applanation is not found in a frame, an applanation buffer can be reviewed. For each applanation, if a length of the applanation buffer does not meet a minimum length requirement, the applanation can be removed from consideration, similar to the designated action 290 for other aspects of the algorithm 270. Likewise, for each applanation, if the length of the applanation buffer meets the minimum length requirement, the first three (3) frames from the applanation buffer can be removed, as these are likely less accurate. Subsequently, a minimum pressure, a maximum pressure, and a mean pressure can be calculated of the remaining applanation buffer(s). If the maximum pressure is greater than the product of the mean pressure and a scaling factor, the applanation can be removed and the maximum pressure and mean pressure can be recalculated. This can be repeated until the maximum pressure is less than the product of the mean pressure and scaling factor. If the minimum pressure is less than the mean pressure divided by a scaling factor, the applanation can be removed and the minimum pressure and mean pressure can be recalculated. This can be repeated until the minimum pressure is greater than the mean pressure divided by the scaling factor. Although these actions are not explicitly illustrated related to calculation action 306 are not separately illustrated as steps or actions of the algorithm 270, a person skilled in the art will appreciate these action can be included as part of the algorithm 270 and/or that other actions can be performed to calculate IOP in view of the information provided by the inputted applanation images that occurred at action 272. Once completed, the data of any remaining good applanations can be saved. Further, after all frames are processed—frames with and without applanations found in the frame—a median pressure of good applanations can be calculated, which can be outputted as the IOP, as shown by output action 308.
The memory 620 can store information within the system 600. In some implementations, the memory 620 can be a computer-readable medium. The memory 620 can, for example, be a volatile memory unit or a non-volatile memory unit. In some implementations, the memory 620 can store information related to image processing, among other information.
The storage device 630 can be capable of providing mass storage for the system 900. In some implementations, the storage device 630 can be a non-transitory computer-readable medium. The storage device 630 can include, for example, a hard disk device, an optical disk device, a solid-date drive, a flash drive, magnetic tape, or some other large capacity storage device. The storage device 630 may alternatively be a cloud storage device, e.g., a logical storage device including multiple physical storage devices distributed on a network and accessed using a network. In some implementations, the information stored on the memory 620 can also or instead be stored on the storage device 630.
The input/output device 640 can provide input/output operations for the system 900. In some implementations, the input/output device 640 can include one or more of network interface devices (e.g., an Ethernet card), a serial communication device (e.g., an RS-232 10 port), and/or a wireless interface device (e.g., a short-range wireless communication device, an 802.11 card, a 3G wireless modem, or a 4G wireless modem). In some implementations, the input/output device 640 can include driver devices configured to receive input data and send output data to other input/output devices, e.g., a keyboard, a printer, and display devices (such as the GUI 12). In some implementations, mobile computing devices, mobile communication devices, and other devices can be used.
In some implementations, the system 600 can be a microcontroller. A microcontroller is a device that contains multiple elements of a computer system in a single electronics package. For example, the single electronics package could contain the processor 610, the memory 620, the storage device 630, and input/output devices 640.
Although an example processing system has been described above, implementations of the subject matter and the functional operations described above can be implemented in other types of digital electronic circuitry, or in computer software, firmware, and/or hardware, including the structures disclosed in this specification and their structural equivalents, or in combinations of one or more of them. Implementations of the subject matter described in this specification can be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a tangible program carrier, for example a computer-readable medium, for execution by, or to control the operation of, a processing system. The computer readable medium can be a machine-readable storage device, a machine-readable storage substrate, a memory device, a composition of matter effecting a machine readable propagated signal, or a combination of one or more of them.
Various embodiments of the present disclosure may be implemented at least in part in any conventional computer programming language. For example, some embodiments may be implemented in a procedural programming language (e.g., “C”), or in an object-oriented programming language (e.g., “C++”). Other embodiments of the invention may be implemented as a pre-configured, stand-along hardware element and/or as preprogrammed hardware elements (e.g., application specific integrated circuits, FPGAs, and digital signal processors), or other related components.
The term “computer system” may encompass all apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, or multiple processors or computers. A processing system can include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them.
A computer program (also known as a program, software, software application, script, executable logic, or code) can be written in any form of programming language, including compiled or interpreted languages, or declarative or procedural languages, and it can be deployed in any form, including as a standalone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program does not necessarily correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.
Such implementation may include a series of computer instructions fixed either on a tangible, non-transitory medium, such as a computer readable medium. The series of computer instructions can embody all or part of the functionality previously described herein with respect to the system. Computer readable media suitable for storing computer program instructions and data include all forms of non-volatile or volatile memory, media and memory devices, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks or magnetic tapes; magneto optical disks; and CD-ROM and DVD-ROM disks. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry. The components of the system can be interconnected by any form or medium of digital data communication, e.g., a communication network. Examples of communication networks include a local area network (“LAN”) and a wide area network (“WAN”), e.g., the Internet.
Those skilled in the art should appreciate that such computer instructions can be written in a number of programming languages for use with many computer architectures or operating systems. Furthermore, such instructions may be stored in any memory device, such as semiconductor, magnetic, optical or other memory devices, and may be transmitted using any communications technology, such as optical, infrared, microwave, or other transmission technologies.
Among other ways, such a computer program product may be distributed as a removable medium with accompanying printed or electronic documentation (e.g., shrink wrapped software), preloaded with a computer system (e.g., on system ROM or fixed disk), or distributed from a server or electronic bulletin board over the network (e.g., the Internet or World Wide Web). In fact, some embodiments may be implemented in a software-as-a-service model (“SAAS”) or cloud computing model. Of course, some embodiments of the present disclosure may be implemented as a combination of both software (e.g., a computer program product) and hardware. Still other embodiments of the present disclosure are implemented as entirely hardware, or entirely software.
Examples of the above-described embodiments can include the following:
One skilled in the art will appreciate further features and advantages of the disclosure based on the above-described embodiments. Accordingly, the disclosure is not to be limited by what has been particularly shown and described, except as indicated by the appended claims. All publications and references cited herein are expressly incorporated herein by reference in their entirety.
The present disclosure claims priority to and the benefit of U.S. Provisional Patent Application No. 63/237,715, entitled “SYSTEMS AND METHODS FOR APPLANATION TONOMETRY AND TONOGRAPHY,” filed on Aug. 27, 2021, the disclosure of which is incorporated by reference herein in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2022/041931 | 8/29/2022 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63237715 | Aug 2021 | US | |
| 63237715 | Aug 2021 | US |
