This invention relates generally to systems and methods for vision testing, and more particularly to systems and methods for measuring aberrations in a patient's vision and in emulating corrective modalities including spectacle lenses to allow the patient to analyze multiple lens designs such as multi-focal spectacle lenses, or progressive add lenses (PALs).
Current vision testing devices that use phoropter technology require that the testing device be positioned intermediate the patient and an image projected on a wall or screen. The phoropter is cumbersome and it commonly introduces instrument accommodation errors in the test results. Moreover, systems that use concave mirrors for reflecting images to the patient typically introduce higher and lower order aberrations since the projected light path and the reflected light path are typically off-axis with respect to an optical axis of the reflective mirror.
Furthermore, systems that measure errors in a patient's vision system and that allow the patient to analyze or compare spectacle lens designs that optimize the patient's vision are nonexistent. For example, there are hundreds of different PAL designs available on the market, and prior art systems provide neither the doctor nor the patient with any practical means to determine, which, if any, design provides the patient with acceptable visual function. Additionally, prior art systems do not allow the patient to preview and compare the visual effects of different PAL lens designs. Nor do prior art systems allow a patient to experience the effects of various lens coatings, such as a photochromic coating, a polarized filter coating, or an antireflective coating.
The present system and methods recognize and address the forgoing considerations, and others, of prior art system and methods.
In an embodiment, the invention is directed to systems and methods for measuring a patient's vision and emulating the corrective properties of spectacle lenses. The system comprises one or more or more processors, at least one wavefront modulator operatively coupled to the processor(s) and configured to modulate a wavefront of an image being projected, a patient testing area that has an examination area in which a patient's eyes are to be located when the patient is positioned in the patient testing area, and a reflective mirror having an optical axis that is normal to the face of the reflective mirror where the optical axis is located intermediate the at least one wavefront modulator and the patient examination area. In various embodiments, processor(s) is configured to adjust the at least one wavefront modulator to minimize optical aberrations and errors that result from the optical axis being located intermediate the wavefront modulator and the patient examination area. In various embodiments, the at least one wavefront modulator may be one or more adjustable optical elements that are operatively coupled to, and controlled by, the processor(s).
In another embodiment, a method for correcting off axis errors introduced in an eye examination testing system comprises the steps of projecting a modulated wavefront of an image onto a mirror having an optical axis that is substantially normal to the face of the reflective mirror, reflecting, by the mirror, the modulated wavefront of the image along a reflected light path into an examination area in which the eyes of a patient are located during a vision testing procedure and adjusting, by the at least one processor, the at least one adjustable optical element to minimize one or more optical aberrations and errors introduced by the mirror due to the off-axis incident and reflected light paths. In various embodiments, the incident light path of the modulated wavefront is off-axis with respect to the optical axis, the reflected light path is off-axis with respect to the optical axis, the wavefront of the image is modulated by at least one adjustable optical element, and the at least one adjustable optical element is controlled by at least one processor.
In yet another embodiments, a system for measuring a patient's vision and emulating a corrective lens comprises at least one processor, at least one wavefront modulator operatively coupled to the at least one processor and configured to modulate a wavefront of an image being projected, a patient testing area that comprises an examination area, and a mirror having an optical axis that is normal to the face of the reflective mirror. In various embodiments, the optical axis is located intermediate the at least one wavefront modulator and the patient examination area. In some embodiments, the at least one processor is configured to receive at least one spectacle lens design and adjust the at least one wavefront modulator to modulate at least one image so that the at least one image reflected off the mirror into the patient testing area emulates the corrective characteristics of the at least one spectacle lens design. In some of these embodiments, the at least one processor is configured to receive a plurality of spectacle lens designs, and adjust the at least one wavefront modulator to modulate the at least one image so that the image reflected off the mirror into the patient testing area emulates the corrective characteristics of at least two spectacle lens designs, side-by-side, to allow the patient being tested to preview and compare the at least two spectacle lens designs substantially simultaneously. In some embodiments, the system further comprises a plurality of wavefront modulators and a plurality of images.
Reference will now be made in detail to embodiments of the present systems and methods, one or more examples of which are illustrated in the accompanying drawings. Each example is provided by way of explanation, not limitation of the present system. In fact, it will be apparent to those skilled in the art that modifications and variations can be made to the present systems and methods without departing from the scope or spirit thereof. For instance, features illustrated or described as part of one embodiment may be used in another embodiment to yield a still further embodiment. Thus, the present systems and methods cover such modifications and variations as come within the scope of the appended claims and their equivalents.
The present systems and methods are directed generally to a vision testing system that remotely creates and projects a corrected image to the eyes of a patient being tested. In general, the system is comprised of a patient testing unit and a remote located viewport having a reflecting mirror contained therein. The patient testing unit has a patient station, such as an examination chair, and one or more image wavefront modulators located above the patient examination chair in a tower. Each image wavefront modulator contains one or more adjustable optical elements, which in preferred embodiments may be continuously variable power lens (CVPL) elements that modulate the wavefront of an image when the image is projected through the adjustable lens elements. The adjustable CVPL lens elements are based on Alvarez lens pairs that impart spherical corrections, and Humphrey's lens pairs (J90° & J45°) that impart astigmatic corrections to the image wavefront. This embodiment could also include other CVPL elements that correct for higher order axi-symmetrical aberrations. When a projected image is passed through the wavefront modulator, the image wavefront is modulated and directed along an incident light path toward the mirror located in the viewport. In preferred embodiments, the mirror is a spherical concave mirror having an optical axis that is normal to a face of the mirror and a radius of curvature of about 2-2.5 meters.
In preferred embodiments, the distance between the wavefront modulator and the viewport mirror, and the viewport mirror and the patient examination chair are each substantially equal to the radius of curvature of the mirror so that the corrective lenses in the image wavefront generator and the spectacle plane of the patient are optically conjugate approximately the midpoint of the wavefront modulator assembly with respect to the mirror. Moreover, the magnification of the power of the corrective lenses in the image wavefront modulator relative to their emulated power at the spectacle plane under these conditions is 1:1, or unity magnification. In this configuration, optical elements contained in the wavefront modulator are effectively emulated as if the optical elements were located adjacent the patient's eyes. In this way, a patient may have their vision tested without having to place optical elements adjacent their eyes during the testing procedure, thereby permitting vision testing under natural viewing conditions.
Because the wavefront modulator and the patient's eyes are off the optical axis of the viewport mirror, aberrations caused the by mirror's orientation are introduced into the modulated wavefront of the image being viewed by the patient. Thus, in order to minimize the aberrations introduced by the use of the mirror in this off-axis configuration, the system may use calibration data in look-up tables to adjust the optical elements in the image wavefront modulator to correct for these aberrations. Moreover, as a patient moves their head when seated in the examination chair, the distance between the patient's eyes and the viewport mirror may change, causing changes in the effective power of the correcting lenses that are relayed by the mirror. Similar to the means of minimizing off-axis mirror aberrations described above, the system may employ a patient gaze tracking system that can detect and track the position of a patient's eyes. This data may be used by the system computer to determine real-time changes in the distance between the patient's eyes and the viewport mirror. Using this data, the system computer can adjust the optical elements in the wavefront modulator to accommodate for the loss of unity of magnification.
Finally, the viewport mirror may also be mounted using a movable mount that is controlled by the system computer. Thus, as the tracking system detects movement of the patient's head and eyes within the vision testing system, the viewport mirror may be rotated along its vertical and/or horizontal axis to align the reflected light path with the patient's eyes as they naturally move about an examination area.
Referring to
Examination Chair
The examination chair 16 is located adjacent, and forward of, tower 12 and is preferably mechanically isolated from the tower so that patient movements in the chair are not transmitted to the components in the tower. Examination chair 16 has a seat portion 24, the position of which is adjustable through a motor (not shown) located in a base 26 of examination chair 16. The motor may be adjusted in response to outputs from the system computer. A seat back 28 has a head rest 30 that may be adjustable through manual or by automatic means that is responsive to the system computer. In various embodiments, an optional head restraint (not shown) may be deployed from the underside of optical tray 20 to aid in stabilizing the patient's head during the exam. The examination chair 16 is configured to receive a patient 32 and to position the patient's eyes within an examination area 34.
Referring to
Wavefront Modulators
Images generated by projectors 54 and 56 pass through respective collimating lenses 58 and 60 to convert divergent beams of light into parallel light beams. The parallel light beams pass through respective adjustable optical elements 50 and 52 (shown in detail in
Suitable continuous variable power lens (CVPL) elements 50 and 52 for wavefront modulators 46 and 48 include, but are not limited to, Alvarez lenses. In general, each CVPL pair comprises two lens elements, where the surface of each may be described by a cubic polynomial equation and each lens element being a mirror image of its companion lens element. As the lens elements translate relative to each other in a direction that is perpendicular to the optical axis of the elements, the optical power imparted to an image passing through the lens pair changes as a function of the amount of lens translation. Stated differently, Alvarez lens elements modulate the wavefront of the image. Thus, in various embodiments, each lens of the CVPL pair is mounted in a movable frame (not shown) that is operatively coupled to actuators (not shown) that are controlled by system computer 110 (
In addition to including accessory lenses in adjustable optical elements 50, phase plates, such as those prepared by lathing the surface of a PMMA disc or other suitable optical material into the desired shape, may also be inserted in accessory slots 92-104. These phase plates may be used to impart additional modulation to the wavefront of the image that may be necessary to emulate the spectacle lens design being emulated. Furthermore, adjustable optical elements 50 may also be used to emulate the optical properties of contact lenses, intraocular lenses, as well as various refractive surgery profiles, such as LASIK or PRK, to allow a patient to evaluate the effectiveness of each potential vision correcting option presented to the patient.
It should be understood from reference to this disclosure that other types of adjustable optical elements and mirrors may be used in wavefront modulators 46 and 48. For example, wavefront modulators 46 and 48 may use fixed and adjustable lens elements to modulate spherical and astigmatic errors, and deformable mirror elements to impart higher order aberrations to the wavefront of the image. Such deformable mirrors that may be responsive to a computer are manufactured by Edmunds Optics, 101 East Gloucester Pike, Barrington, N.J. 08007-1380. In still other embodiments, the adjustable CVPL described above may be replaced by fixed lenses, by one or more deformable mirrors, or by any combination of fixed lenses, deformable mirrors, and CVPL elements. In various embodiments, adjustable CVPL elements may be employed to correct for lower order aberrations of spherical error and astigmatism, and deformable mirrors may be employed to correct for higher order aberrations thereby using the dynamic range of the adjustable mirrors only for creating higher order corrections.
Viewport
Referring once again to
In embodiments that use a concave spherical field mirror 42, a distance between a spectacle plane adjacent the patient's eyes (at examination area 34) to field mirror 42 and from the center of adjustable optical elements 50 and 52 to field mirror 42 should each be approximately equal to the radius of curvature of the mirror. In this configuration, the corrective lenses in the image wavefront modulator and the spectacle plane are optically conjugate with respect to the field mirror. Moreover, the magnification of the image relative to the object under these conditions is 1:1 or unity magnification. Because wavefront modulators 46 and 48 and the examination area 34 are located at optical planes that are substantially conjugate with respect to the field mirror, adjustable optical elements 50 and 52 are optically relayed to the spectacle plane located in examination area 34 and produce the same effective power at spectacle plane as they produce in the wavefront modulators. Thus, a patient seated in vision testing system 10 views the image as if adjustable optical elements 50 and 52 are positioned adjacent their eyes.
Vision Testing System with Compare Features
Control Terminal
Referring once more to
System computer 110 is also configured to receive inputs from touch display 106 and operator input device 108. These inputs may be used to control the position of examination chair 16 by way of exam chair position control unit 114 to ensure that the patient's eyes are properly positioned in the examination area 34. In some embodiments, operator input may be received via remote control inputs such over an Internet connection 116 when the operator is located remote to vision testing system 10. Moreover, system computer 110 is also configured to receive patient input from patient input means 40. In this way, the patient can provide various inputs during an examination that would cause system computer 110 to adjust respective adjustable optical elements 50 and 52. In this way, the system may be configured to use patient input to facilitate the examination.
In addition to receiving inputs from various subsystems (e.g., the patient and operator controls and the tracking system), system computer 110 also provides outputs to a display driver 118 that drives image projectors 54 and 56. System computer 110 also provides outputs to a lens motion control system 120 that directs the actuators (not shown) that drive the respective adjustable optical lenses 50 and 52 for the right and left channels of the wavefront modulators 46 and 48, respectively. Lens motion controller 120 also controls the position of accessory lenses 92-104.
In addition to receiving local inputs and sending local outputs, system computer 110 may also be operatively coupled to a central repository server 122 over a network connection 124 (e.g. the Internet, wide area network or cellular network). Moreover, in some embodiments, multiple vision testing systems 10A and 10B may be operatively coupled to central repository server 122 over networks 124. Server 122 may comprise an information storage device, such as, for example, a high-capacity hard drive or other non-volatile memory devices to allow patient data to be stored and transmitted to lens manufacturing facilities. Server 122 may also be configured to respond to queries from one or more of the vision testing systems 10, 10A and 10B and may provide any requested service such as performing statistical analysis on data obtained by the vision testing systems.
Referring once again to
Astigmatism, higher order aberrations and other optical errors may be introduced into vision testing system 10 in various ways. For example, off axis angles α, α′ and β induce astigmatism and higher and lower order aberrations into the modulated image wavefronts. In various embodiments, these aberrations may be compensated for, completely, or in part, by adjusting the appropriate adjustable optical elements 50 and 52 in respective wavefront modulators 46 and 48. That is, one or more of the lens pairs 76-90 can be adjusted to eliminate or minimize the aberrations that are introduced by off-axis incident and reflected light paths. Moreover, because α, α′ and β may change as the position of the patient's eyes move about examination area 34, system computer 110 (
As previously indicated, operating vision testing system 10 at, or near, the condition of unity magnification is preferred. However, unity magnification is not always possible since the patient is free to move about examination area 34 during testing. That is, as the patient's eyes move toward and away from field mirror 42, changes in the effective lens power may result. Vision testing system 10 may compensate for such changes in effective lens power through use of the following equation:
Po=Pc(M)2
where Po is the effective power of the lens at the patient's spectacle plane, Pc is the actual power of the corrective lenses, and M is the magnification, given by Di/Do, where Do is the distance between the corrective lenses and the field mirror and Di is the distance between the field mirror and the patient's eyes. The above formula provides corrective conversions that may be stored in calibration tables and used by system computer 110 to adjust one or more lenses in adjustable optical elements 50 and 52 to correct for such non-unity magnifications. Such corrections may be automatically made by system computer 110 without input by the operator by using patient tracking information data provided by tracking cameras 44 and tracking system 112.
Referring to
Referring to
Vision testing system 10 may be configured to simulate a progressive lens by modulating the image wavefront based on the lens design. For example, a progressive lens design that describes a unique value of sph, cyl, and HOA for a region of the lens that is subtended by the eye's entrance pupil for each gaze angle pairs θ and Δ may be loaded into system computer 110. The lens design may be provided by a lens manufacturer, measured by an appropriate lens mapper, or measured by a spatially resolved refractometer, which may be provided as an accessory to vision testing system 10. The lens information may then be used to modulate the wavefront of the image in order to simulate the properties of the lens design for the patient as a function of the gaze angles.
In various embodiments, as the patient's gaze angles change, system computer 110 uses information received by tracking system 112 to compute the gaze angle pair at a rate of, for example, 10-30 Hz, and uses the tracking information to drive lens motion controller 120 to adjust adjustable optical elements 50 and 52 in respective wavefront modulators 46 and 48 to accurately replicate the power of the PAL design exactly as if the patient were wearing the progressive lens and was looking through it at the measured gaze angle. Examples of the area of the lens surface subtended by different gaze angles is shown in
As shown in
At step 302, image projectors 54, 56 (
At step 304, the modulated wavefront of the image is reflected by mirror 42 along a reflected light path 128 that is also off-axis with respect to optical axis 130. In various embodiments, mirror 42 may be a concave spherical mirror, which imparts various higher order and lower order aberrations into the modulated wavefront of the image when the incident and reflected light paths are off-axis with respect to the mirror's optical axis. Thus, at step 306, the system computer 110 may be configured to adjust optical elements 50, 52 in respective wavefront modulators 46, 48 to minimize aberrations introduced by the mirror. The adjustment factors may be determined during calibration of vision testing system 10 and stored in calibration look-up tables.
In various embodiments, at step 308, the system is configured to track the position of a patient's, head, eyes and gaze using tracking system 112. The position of the patient's head, eyes and gaze may be used to determine the locations of the patient's eyes with respect to wavefront modulator 46, 48, mirror 42 and reflected light path 128. In various embodiments, at step 310, system computer 110 may be configured to use the data calculated by tracking system 112 to adjust optical elements 50, 52 to minimize aberrations and errors (e.g., changes in the effective lens power) introduced as a result of the patient's eyes moving out of the conjugate plane with optical elements 50, 52, thereby resulting in a loss of unity magnification between the adjustable lenses and the present location of the patient's spectacle plane. Once more, system computer 110 may use calibration data stored in look-up tables to impart the appropriate adjustments to optical elements 50, 52 to accommodate for patient movement within the vision testing device.
In various embodiments, movable mirror mounting 43 coupled to field mirror 42 and to system computer 110 may be used to align reflected light path 128 with the patient's eyes as the patient move about examination area 34. In this way, as eye tracking data is obtained by tracking system 112, system computer 110 may cause the movable mirror mount to pivot mirror 42 about its vertical and horizontal axis in an effort to move reflected light path 128 (
The present systems and methods provide for a vision testing system that measures optical errors (e.g., lower order and higher order aberrations) in a patient's vision system without having to dispose optical lenses or instruments adjacent the patient's face. Moreover, the system allows a patient to preview and compare potential optical corrections and to select an optimum solution. Moreover, the system may also allow the patient to compare multiple lens designs to determine which design provides the best quality of image or that is otherwise preferred. These images may be compared simultaneously or substantially simultaneously on a side-by-side basis. Thus a plurality of spectacle lenses may be emulated simultaneously or perceived simultaneously by the patient. By activating a wavefront modulator for each eye, a binocular comparison of images for each lens can be previewed and compared for each spectacle lens design. As a result, systems and methods are provided to characterize the optical properties of any spectacle lens, and to accurately emulate those optical properties for a patient under realistic viewing conditions over near, intermediate, and far away distances and over a range of image illuminations, colors and contrasts. By adjusting the output of the image projectors, patients can see how the spectacle lens designs compare as illumination and contrast rises or fall and as colors change. This allows the patient to preview, compare, and select a particular spectacle lens design or feature that they prefer based upon the patient's subjective appraisal.
By using a head, eye and gaze tracking system, the system can stabilize the image into the appropriate image plane, thereby relieving the patient of the need to hold still during the test and facilitates a more realistic emulation of spectacle lens performance under natural viewing conditions. The testing is also done with no instruments or other visual obstructions in the patient's field of view. Optical parameters used to manufacture or select spectacle lenses can be determined in much higher resolution increments, such as 0.01D, as opposed to the 0.25D increments provided by prior art systems and methods.
Many modifications and other embodiments of the disclosed system and method will come to mind to one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. While examples discussed above cover the use of the invention in the context of a vision testing system, the invention may be used in any other suitable context such as emulating vision correction by spectacle lenses, contact lenses, intraocular implants and Lasik surgery. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for the purposes of limitation.
This application claims the benefit of, and incorporates by reference in its entirety, U.S. Provisional Patent Application No. 61/604,310, filed Feb. 28, 2012.
Number | Date | Country | |
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61604310 | Feb 2012 | US |