TWI844707B - Method and apparatus for refraction and vision measurement - Google Patents

Abstract

A consumer product such as a refraction measurement device may be used to obtain refraction measurement results, allowing a consumer to track their vision without having to visit an optometrist or ophthalmologist. Such a consumer product may work in conjunction with a smartphone or other product having a touch screen that presents an image to the refraction measurement device. The smartphone may have a resolution ratio, sometimes measured in PPI or pixels per inch, that is unknown to the user and/or the refraction measurement device. One aspect of the invention is to provide an optical interface for a user to manually match the viewing port boundaries of the smartphone to coincide with the viewing port boundaries of the refraction measurement device. Another aspect of the invention is the use of pre-distortion in the image presented to the user. By noting the corrective actions applied by the user to the refraction measurement device, the user's own refractive error may be derived.

Description

Methods and systems for refraction and vision measurement

The present invention generally relates to vision testing and refraction measurement systems that are attached to a display, such as personal vision tracking systems, visual field calibration systems, and insight systems. More specifically, the present invention relates to methods and systems for measuring characteristics of displays and correcting optical aberrations in such systems. Any system intended to measure vision and ocular characteristics (e.g., refraction), where the system includes a display, an optical system consisting of refractive elements and/or reflective elements (e.g., lenses and/or mirrors) may encounter two main problems: the characteristics of the display may be unknown (e.g., the display may be part of a smartphone and the phone resolution is not well reported), and the optical system creates aberrations for the displayed image. The proposed invention describes methods and systems for overcoming these problems.

Cross references to related applications:

This application is a continuation or continuation-in-part of the following patent applications, the contents of which are incorporated herein by reference.

U.S. Patent Application No. 16/685,017, filed on November 15, 2019, entitled Automated Personal Vision Tracker, is a continuation-in-part of U.S. Patent Application No. 16/276,302, filed on February 14, 2019, entitled Optical Method to Assess the Refractive Properties of an Optical System, which is now U.S. Patent No. 10,488,507, which is a continuation-in-part of U.S. Patent Application No. 15491557, filed on April 19, 2017, rather than Patent No. 10,206,566, which claims priority from Provisional Patent Application No. 62409276, filed on October 17, 2016.

This application is a continuation-in-part of U.S. patent application No. 16/176,631 filed on October 31, 2018, entitled Smart Phone Based Virtual Visual Charts for Measuring Visual Acuity, which claims priority from provisional patent application No. 62/579,558, which has a priority date of October 31, 2017.

This application claims priority to provisional patent application 62/876,889 filed on July 22, 2019.

No Copyright and Trademark Notices Applicable:

This application contains material that is or may be protected by copyright and/or trademark. The copyright and trademark owners have no objection to the facsimile reproduction of any patented invention as it appears in the Patent and Trademark Office files or records, but if not, all copyright and trademark rights are reserved regardless. Such trademarks may include "EyeQue," "PVT," "Personal Vision Tracker," "Insight," "VisionCheck," and others.

Vision is arguably the most important sense organ. The human eye and its direct connection to the human brain is a very advanced optical system. Light from the environment passes through the eye's optical system consisting of the cornea, pupil, and lens and is focused to produce an image on the retina. As with all optical systems, the propagation of light through the eye's optics is affected by aberrations. The most common forms of aberrations in the eye are defocus and astigmatism. These low-order aberrations are responsible for the most common refractive conditions of the eye, myopia (ophthalmic myopia) and hyperopia (ophthalmic farsightedness). Higher-order aberrations also exist and can be most conveniently described by Zernike polynomials. These generally have a lesser impact on visual function. The eye, like any other organ of the human body, can be subject to a variety of diseases and conditions, the most prominent of which are: cataracts, age-related macular degeneration (AMD), glaucoma, diabetic retinopathy and dry eye. Other conditions exist and should also be considered within the scope of this application.

Ophthalmic measurements are critical for eye health and proper vision. Those ophthalmic measurements can be divided into objective and subjective types. Objective types of measurements provide physiological, physical (e.g., mechanical or optical), biological, or functional metrics without input from the individual being measured (patient, subject, user, or consumer). Examples of objective tests include, but are not limited to, OCT (optical coherence tomography for three-dimensional and cross-sectional imaging of the eye), scanning laser ophthalmoscopy (SLO, for spectral imaging of the retina), fundus imaging (for displaying images of the retina), autorefractometer (for refraction measurement), keratometer (for providing corneal contour), tonometer (for measuring IOP - intraocular pressure). Subjective measurements give metrics that are related to individual input. That is, they provide parameters that also take into account the individual's brain function, perception, and cognitive abilities. Examples of subjective tests include, but are not limited to, visual acuity tests, contrast sensitivity tests, trochanter refraction tests, color vision tests, visual field tests, and EyeQuePVT and Insight.

Currently, both objective and subjective eye examinations (measurements) are performed by an ophthalmologist or optometrist. The process typically involves the patient scheduling an appointment, waiting for the appointment, traveling to the appointment location (e.g., an office or clinic), waiting in line, undergoing multiple tests using various tools, and potentially moving between different technicians and different ophthalmologists. The extended wait times for appointments and waiting in line at appointment locations, as well as the hassle of conducting tests with different professionals and the duration of these tests seem to be daunting to many patients. Furthermore, the separate results associated with the process and even the requirement to remember to start the process may discourage patients from undergoing the process.

Furthermore, approximately 2.5 billion people currently have no access to eye and vision care at all. In some parts of the world in particular, the cost of an eye exam may be considered prohibitive. This creates a barrier to eye care services in third world countries, for example. Cost, time consumption and perceived hassles also sometimes make repeated eye exams impractical, especially at the required frequency. In special cases (e.g. after refractive or cataract surgery), repeated measurements may be necessary to track the patient's progress over time and the success of the surgery. Furthermore, even under normal circumstances, measurements taken in a doctor's office represent only one point in time. The circumstances under which the measurements were taken may not be optimal or fully representative of the patient's characteristics. The patient may be tired, nervous or irritated (a doctor's visit can be stressful, but the constant testing and questions and choices can also raise the patient's stress level), or simply in a bad mood. Even the doctor's own psychological state may affect the way the measurement is taken. In addition to this, the time of day and other environmental conditions (whether directly, such as lighting conditions, or indirectly, such as temperature) may affect the measurement and provide incomplete or erroneous information.

The availability of information on the Internet, especially including medical information, the increased awareness of preventive medicine, and the advent of telemedicine have allowed many people to take control of their health. In today's world, devices for screening, monitoring, and tracking medical conditions are common, such as blood pressure measuring devices and blood glucose monitors. Technological advances allow people to be more independent in diagnosing, preventing, and tracking a variety of health conditions. In addition, many people prefer to perform these activities from the comfort of their own homes without the need for appointments or other time-consuming activities. If something unusual occurs, they will call or email their physician to consult on the appropriate course of action.

Advances in technology have effectively made computers with screens and cameras ubiquitous in the form of laptops, tablets, and smartphones. As a result, many people have devices that are already capable of processing displayed and recorded information.

All of this brings with it the need for a range of devices that will enable users to perform ophthalmic measurements in a timely and cost-effective manner at home by themselves. It should be clear that the quality of these measurements and their accuracy and precision should meet or exceed the standards of current measurement methods.

This vision can be further enhanced by using cloud-based data and analytics that have complete access to the entire history of patient examinations, tests, and measurements. In addition, the use of artificial intelligence (AI) will enable machine learning and big data-based diagnostics. This can be done by way of data mining, neural network decision making, and pattern detection and recognition as some examples of AI capabilities.

In summary, the vision of eye care in the near future will look like: A complete solution for eye and vision care for consumers and physicians; A set of remote, self-administered tests for disease and function; Measurement enabled by technology and devices, with AI used for analysis, tracking, and reporting. Enhanced by big data statistics and insights.

To put it simply, for example: a person sits comfortably on a couch at home, uses a device to take various measurements, and then uploads the data to AI for analysis. The AI will let the patient know the results and notify the doctor. The AI will trigger an alert for the person and the doctor if necessary. Unless there is a serious problem (such as surgery), the person does not need to get up. All other issues will be handled remotely (such as email/phone/video conference with the doctor, ordering glasses, having them delivered to the home and direct delivery of doctor-prescribed medicines).

Despite the obvious move towards "targeting consumers", these approaches could be easily implemented as models for more businesses. An example of such an implementation would have a tiered structure where entities such as hospitals, associations, or health insurance companies equip doctors with the ability to provide such devices and capabilities to their patients. These devices are all connected to the cloud through user accounts, and measurements are streamed directly into the user's account (and possibly their medical records). These accounts can be connected to one or more doctors, and can also be transferred and shared.

The known prior art failed to anticipate or disclose the principles of the present invention.

In the prior art, minimization of the field of view (FoV) and image size, especially in personal vision tracking systems, provides a method to overcome distortion aberrations in the system, which causes the image presented to the user to form curved lines despite having straight lines on the display. The field of view calibration system includes an aspheric lens to overcome the distortion of the lines presented to the user. This type of hardware solution makes the system more complex and expensive.

The pixel density (PPI) property of a display is critical in determining the size of images displayed. Scaling between different displays is required to allow the image to be displayed correctly. Current systems rely on input from the phone firmware to indicate the correct resolution in the form of PPI. Some current phones do not report this value correctly. Therefore for these phone displays the correct PPI must be entered manually on the back end of the software.

Therefore, there is a long-standing need for the present invention in this field.

The present invention overcomes the deficiencies of the prior art by providing an unobvious and unique combination and configuration of methods and components to calibrate optical aberrations in a system and allow a self-correcting method to measure display resolution.

The present invention overcomes the deficiencies of the prior art by using a calibration process to measure display resolution and create a correction map for distortion aberrations.

In one embodiment of the invention, the display is part of a smart phone. What is displayed to the user is a rectangle of the correct aspect ratio as the attached device. The attached device specifications are well known. The user then adjusts and aligns the rectangle on the screen to match the attached outline of the device. The known specifications of the device and the input rectangle dimensions in pixels can then be used to calculate the phone's resolution or more specifically its PPI. This can then be used for alignment and scaling of images on the display. This can in turn be used to make visual acuity and refraction measurements.

In another embodiment of the present invention, the resolution measurement is based on using an external sensor input. An example of this embodiment can be implemented using a smartphone as a display device. The attached systems can then have known contact points and defined distances. When the attached system is physically connected to the phone, the touch points indicate the pixel locations of those touch points, which in turn are used in conjunction with the known distances between the points to calculate the display resolution and PPI.

In another embodiment of the invention, an optical system is attached to a display. The display presents images to the user. These images can be used for vision testing or as a means of measuring the refraction of the optical system. For example, the optical system can be the user's eye and the refraction measurement can be the refractive correction required for the eye. The optical system introduces aberrations to the user, in particular distortion aberrations. This causes the image to appear unclear and malformed. In the present invention, a method is proposed to solve the image distortion by means of pre-distortion of the image on the display. The image is pre-distorted with a distortion opposite to the distortion introduced by the optical system, so that if viewed directly on the display it will appear distorted, while viewing through an optical system with inherent distortion will cause the image to appear sharp and undistorted. The main principle of pre-distortion is the calibration of spatially correlated image bending based on the original system distortion map.

These and other objects and advantages will become apparent when the following detailed description is considered in conjunction with the accompanying drawings.

100: List of steps to get glasses so far

200: Suggested steps to get glasses

300: Attached equipment, such as personal view tracking

400: Display device, such as a smartphone

430: User-adjustable markings to fit attached device

500: Alternative attachment equipment, such as insight equipment

540: Input area for attached devices

FIG1 Current process for obtaining glasses; FIG2 Proposed example of process for obtaining glasses; FIG3 Proposed business model example; FIG4A Certain example of implementing display resolution measurement; FIG4B Another example of implementing display resolution measurement; FIG4C Another example of implementing display resolution measurement; FIG5 Example of implementing display resolution measurement; FIG6A Certain example of image distortion correction; FIG6B Another example of image distortion correction; FIG6C Another example of image distortion correction.

The following describes in detail certain specific embodiments of the present invention. However, the present invention can be embodied in many different ways as defined and covered by the patent application and its equivalents. In the specification, the drawings are marked with the same parts marked with the same numerical symbols throughout.

Unless otherwise stated in this specification or claims, all terms used in the specification and claims shall have the meanings commonly assigned to these terms by persons skilled in the art.

Unless the context clearly requires otherwise, throughout the specification and claims, the words "include," "including," and similar words should be construed in an inclusive sense rather than an exclusive or exhaustive sense; that is, in a sense, "including but not limited to." Words using the singular or plural number also include the plural or singular number, respectively. In addition, when used in this application, the words "herein," "above," "below," and words of similar meaning shall refer to this application as a whole and not to any particular parts of this application.

In an embodiment of the present invention, a resolution measurement is performed on a display (e.g., a display of a smartphone). A user is asked to connect to a device used in a refractive or vision test. A shape that is the same shape and aspect ratio as the attached device is then presented to the user on the display. The user then adjusts the size and position of the displayed shape until it matches the base outline of the connected device. Figures 4A-C show examples of implementations of this method. Figure 4A shows a device attached to a smartphone display, where the outline shape presented to the user by the smartphone display is too large compared to the base of the attached device. Figure 4C shows a device attached to a smartphone display, where the outline shape presented to the user by the smartphone display is too small compared to the base of the attached device. Figure 4B shows the device attached to a smartphone display, where the outline shape presented to the user is the proper size for the base to which the device is attached. At that point, the user can indicate a match and then measure the size of the shape in pixels. Since the specifications of the device are well known, the display resolution (PPI - pixel density) can be calculated as follows:

where _dp is the final matching size of the displayed shape in pixels, taken from the shape drawn on the monitor, and D _D is the shape size of the well-known base of the device in inches.

In another embodiment of the invention, resolution measurement can be performed by using sensors rather than by user input. In a proposed implementation, the measuring device can be mounted on a frame that includes at least two touch points, or the device itself has at least two touch points embedded on it. These touch points are made of a material that allows interaction with the touch screen. An example is to attach a rubber dome to a slightly conductive plastic frame. The touch points are then connected to a display that includes a touch screen (for example, like on a smartphone). The display then detects the two touch points and records the pixel value of each point. The distance between the points can then be calculated according to the following formula:

Where ( _x1 , _x2 , _y1 , _y2 ) are the coordinates of touch points 1 and 2 detected on the screen. The same formula as above can then be used to calculate PPI, where D _D is the distance between touch points on the device in inches. In another embodiment of the invention, three or more touch points can be implemented so that resolution can be measured in more than one direction.

Figure 5 shows an example implementation of the proposed embodiment. In this figure, the attached device is held in a frame with two touch points. The distance between them is well known. The device with the frame and touch points is then connected to a touchable display. The display then detects the touch points and can determine the touch pixels. The process described above for calculating PPI can then be followed.

In another embodiment of the invention, a method for aberration correction is proposed. In particular, distortion-type aberrations. The distortion is mapped in space, and the distortion map is used to create a pre-distorted image that presents a sharp image to the user when viewed through twisted optics. The distortion map can be obtained by simulation or empirically. Simulation of the distortion map can be achieved by ray tracing or other computational methods (analytical or numerical). For example, empirical mapping can be accomplished by observing with an optical device, displaying lines at different distances, and assigning a curvature to each line as a function of the distance from the center to obtain a straight line when viewed through the optical system. In other embodiments, a grid or points rather than lines may be used for mapping, in which case the curvature is used to straighten the grid or create an array of equidistant points, respectively. In an example embodiment, the curvature will be matched to the radius of a circle. In another embodiment, the curve will be matched to a polynomial expansion of a function. A best fit may be made to match the curvature as a function of the distance from the center. This in turn may be used to correct the image presented to the user by the optical device. In an example embodiment, for a center-symmetric image, the distance measurement may be bidirectional (between two coaxial lines) rather than a single distance to the center. In a simplified implementation, where the image presented is intended to be a linear bar, the curvature can be considered uniform for the entire bar based on, for example, the curvature of the center of the bar. This simplifies having to create different curvatures for the sides of the bar. This approximation works well if the bar thickness is small relative to the radius of curvature.

Figures 6A-C show an illustration of an example implementation of distortion correction. The figure uses two color bars as the displayed image. The image can be used to demonstrate distortion correction, as well as for use in the refractive measurement device of [PVT Patent]. The figure shows the image display on the display in the first row. The second and third rows show the two bars that can be seen through the attached device at two different positions along the bars on the display. The last row shows a situation where the lines appear to overlap with the attached device. For example, 0D refraction is such a case. It shows the possible ambiguity of the overlapping situation required in the refractive measurement of [PVT Patent]. Figure 6A shows the distortion present in the device, where the image on the display is expected without any correction through the system. The figure shows the fact that the straight lines on the display are equivalent to curved lines through the optical device of the device. This will cause errors and ambiguity to the user when observing the image and performing the refractive test. Figure 6B shows a prior art form of controlling the distortion in the image. The solution used is to reduce the length of the bar to minimize the effect of the curvature of the line caused by the distortion of the optical system. The disadvantages of this method are obvious, because the curvature is not reduced, but just not as obvious. The shorter length of the line causes many users to encounter problems when observing the line and performing the test (aligning the bar). Figure 6C proposes an implementation of the solution of the present invention, in which the lines on the display are pre-distorted by optical devices to produce a clear image. The process described so far is used to construct a map of the curvature of the bars as a function of the distance between the bars to produce the straight line when viewed through the optics of the attached device (rows 2-4 in the figure).

The above detailed description of embodiments of the present invention is not intended to be exhaustive or to limit the present invention to the precise form disclosed above. Although specific embodiments and examples of the present invention are described above for illustrative purposes, various equivalent modifications may be made within the scope of the present invention as will be recognized by those skilled in the relevant art. For example, although the steps are presented in a given order, alternative embodiments may perform routines with steps in a different order. The teachings of the present invention provided herein may be applied to other systems, not just the system described herein. The various embodiments described herein may be combined to provide further embodiments. These and other changes may be made to the present invention in light of the detailed description.

All of the above references and U.S. patents and applications are incorporated herein by reference. If necessary, aspects of the present invention may be modified to adopt the systems, functions and concepts of the various patents and applications mentioned above to provide further embodiments of the present invention.

200: Suggested steps to get glasses

Claims (9)

A method of measuring a refractive error of an optical system, the method comprising the steps of: a) using a first lens for demagnification; b) using a second and a third lens, the second and third lenses each defining a slit, and wherein the second lens has a different color than the third lens; c) using a viewing screen to project a first line through the first and second lenses, and using the viewing screen to project a second line through the first and third lenses, wherein the first and second lines are pre-distorted so as to project relatively straight lines perceived by a user; d) rotating the first and second lines projected by the viewing screen using a meridian angle; e) using the first meridian angle f) using a second meridian angle, the second meridian angle being a predetermined angular difference from the first meridian angle, to adjust the first and second lines so that the first and second lines are aligned to obtain a second distance of line movement for the second meridian angle as perceived by the optical system being tested; and g) using the first and second meridian angles, the first and second distances of line movement are combined to obtain a refractive error of the optical system. The method as claimed in claim 1 further comprises the step of projecting an observation port mark (430) on the observation screen; the user adjusts the observation port screen to coincide with the observation ports of the first and second lens lines. The method as claimed in claim 2 further includes the step of calculating the display resolution of the display screen by using the size of the viewing port screen specification adjusted by the user. The method as claimed in claim 2 further comprises calculating the display resolution by the following formula:

A system for measuring refractive error of an optical system, the system comprising: a) a first lens for zooming; b) a second and a third lens, wherein the second and the third lens each define a slit, and wherein the second lens has a different color than the third lens; c) a viewing screen for projecting a first line through the first and second lenses, and projecting a second line through the first and third lenses using the viewing screen, wherein the first and second lines are pre-distorted so as to project relatively straight lines perceived by a user; d) rotating the first and second lines projected by the viewing screen using a meridian angle; e) a first meridian angle , which is used to initially place first and second lines projected by a viewing screen, and the first and second lines are adjusted to align using the optical system being tested to yield a first distance of line movement for a first meridian angle; f) a second meridian angle, which is a predetermined angular difference from the first meridian angle, as perceived by the optical system being tested, and the first and second lines are adjusted so that the first and second lines are aligned to yield a second distance of line movement for the second meridian angle; and g) the first and second distances of line movement are used in conjunction with the first and second meridian angles to yield a refractive error of the optical system. The system as claimed in claim 5 further comprises an observation port marker (430) placed on the observation screen; adjusting the observation port screen to coincide with the observation ports of the first and second lens lines. A system as claimed in claim 5, wherein the display resolution is derived by using the dimensions of the observation port screen specification. The system of claim 6, wherein the display resolution is obtained by the following formula:

A system as described in claim 6, wherein the second lens is the same color as the third lens.