Source: https://patents.google.com/patent/EP1383429B1/en
Timestamp: 2020-01-28 22:40:20
Document Index: 643484937

Matched Legal Cases: ['art 52', 'art 54', 'art 52', 'art 52', 'art 54', 'art 54', 'art 54']

EP1383429B1 - Iris pattern recognition and alignment - Google Patents
EP1383429B1
EP1383429B1 EP01274188A EP01274188A EP1383429B1 EP 1383429 B1 EP1383429 B1 EP 1383429B1 EP 01274188 A EP01274188 A EP 01274188A EP 01274188 A EP01274188 A EP 01274188A EP 1383429 B1 EP1383429 B1 EP 1383429B1
EP1383429A1 (en
210000000554 Iris Anatomy 0 claims description title 152
238000003909 pattern recognition Methods 0 claims description title 9
210000001747 Pupil Anatomy 0 claims description 65
206010027646 Miosis Diseases 0 claims description 50
208000006550 Mydriasis Diseases 0 claims description 43
This application is related to PCT EP00/10373 .
The popularity of photorefractive surgery for the correction or enhancement of vision continues to rise. Techniques such as photorefractive keratotomy (PRK), laser in situ keratomileusis (LASIK), laser epithelial keratomileusis (LASEK) and variations thereof are now commonly used to correct the effects of nearsightedness (myopia), farsightnesses (hyperopia), and astigmatism, in addition to more traditional retinal surgery and other ocular surgical procedures. These vision defects are typically treated by laser ablating the cornea to steepen or flatten it according to its deviation from a geometry that is expected provide normal vision. A topography device such as, e.g., an Orbscan® corneal topographer (Bausch & Lomb/Orbtek, Salt Lake City, Utah) is routinely used to acquire the diagnostic information about the shape and other characteristics of the cornea. A surgeon can then use a laser programmed with this topographic information to appropriately ablate the corneal surface.
Basically, hyperopia and myopia, and astigmatism, are known as lower order aberrations referred to as defocus and cylinder, respectively. It is well known that higher order aberrations in addition to lower order aberrations degrade vision quality. Typical higher order aberrations include spherical aberration, coma, and compound astigmatisms. It is possible to measure these higher order aberrations with wavefront measuring devices such as disclosed in Williams U.S. Patent No. 5,777,719 , which describes an aberrometer instrument incorporating a Hartmann-Shack wavefront sensor to quantify higher order aberrations in the eye. The diagnostic measurement of higher order aberrations has lead to the ongoing development of systems and methods for customized ablation of the cornea and lenses used in or on the eye. The goal of customized ablation is to provide ever increasing visual quality in terms of acuity and contrast sensitivity (sometimes referred to as supernormal vision), as well as consistent image quality.
One technique being developed to address these issues is referred to as iris pattern recognition. Rotation of the eye, for example, can sometimes be measured by identifying iris patterns using markers (artificial) or landmarks (natural). Since each person's iris is as unique as their fingerprints, it is proposed that various iris landmarks can be used to identify changing eye orientation. The reader is referred to the web site addresses: http://www.iriscan.com and http://schorlab.berkeley.edu for further information about iris pattern identification and eye movement. Notwithstanding that iris landmarks remain constant over the lifetime of the individual, it has been found that often the change in pupil size between diagnostic evaluation (dilated) and the treatment phase (constricted) is sufficient to deform or otherwise obscure the landmark, making it undetectable by conventional iris recognition software between diagnostic evaluation and treatment. Since it is highly desirable to be able to align the photoablative treatment of the cornea or other eye sites with the diagnostic measurement reference upon which it is based, there is a recognized need for methods and apparatus to acquire and maintain accurate alignment. A solution is proposed in applicant's co-pending patent application PCT/EP00/10373 . That application discusses associating an artificially applied marker with diagnostic stage and therapeutic stage iris images in order to align these images at treatment. Thermal and dye based marks, for example, are suggested as artificial markers. It is appreciated, however, that patient discomfort, efficiency and accuracy are some disadvantages of current iris recognition and alignment means.
In an embodiment of the invention, an improvement is described for aligning a diagnostic iris image of a patient's eye with a treatment iris image of the patient's eye via iris pattern recognition. A method which does not form a part of the invention is disclosed, wherein a diagnostic iris image of a patient's eye having a dilated pupil is attempted to be aligned with a treatment iris image of the eye having a constricted pupil, where it is attempted to identify an iris recognition landmark in the dilated pupil diagnostic iris image with the corresponding iris landmark in the constricted pupil treatment iris image, but due to deformation of the iris landmark associated with the change in pupil size, those corresponding landmarks cannot be identified for use as naturally occurring alignment markers in the iris, in order to accurately align a calculated laser treatment that is derived from a diagnostic measurement associated with the dilated pupil. The method involves obtaining a sequential plurality of diagnostic iris images including a dilated pupil, a constricted pupil, and selected intermediate pupil sizes by capturing diagnostic images of the iris when it is illuminated by controlled amounts of visible illumination. Each of the sequential diagnostic iris images will contain at least an indicia of the iris recognition landmark such that in going from a dilated pupil to a constricted pupil in sequential steps, the landmark can be tracked from the dilated pupil image to the constricted pupil image. A diagnostic measurement of the patient's eye, preferably including a direct wavefront aberration measurement or a diagnostic measurement from which wavefront aberration data can be derived, is also obtained with the eye having a dilated or dark adapted pupil condition. An iris image of the patient's eye immediate prior to treatment, or a real time image is also obtained and due to environmental conditions in the treatment stage, the treatment iris image includes a constricted pupil. By tracking the iris recognition landmark through the series of diagnostic iris images from the dilated pupil condition upon which the diagnostic measurement and the laser treatment is based to the constricted pupil condition, the treatment iris image can be aligned with the resultant constricted pupil diagnostic image by matching and/or correlating the iris recognition landmark between the two constricted pupil images. The tracking and correlation of the diagnostic iris images can be accomplished by processing electronics and software in a treatment phase, and a resultant aligned diagnostic image can be exported to the laser treatment system where appropriate processing hardware and software can align the treatment iris image with the diagnostic iris image and adjust the laser treatment pattern accordingly. Alternatively, the entire plurality of diagnostic iris images can be exported to the laser treatment system where appropriate processing hardware and software can align a treatment iris image with the corresponding pupil size diagnostic iris image via iris landmark identification. It will be appreciated by those skilled in the art that the export of diagnostic iris image data to the laser treatment system can be accomplished in a variety of ways including, but not limited to, land based or wireless telecommunications, computer storage media such as disk or CD, via the Internet or other networks, and so on. A pupil translation is also used to ultimately adjust a laser treatment to the eye. This involves determining an illumination independent reference landmark on the eye, preferably a limbal edge, calculating a center position of the pupil with respect to the reference landmark wherein this calculation is performed with respect to the dilated pupil diagnostic iris image, making another center position calculation of the pupil with respect to the same reference landmark in relation to the constricted pupil diagnostic iris image, determining a vector displacement value for the constricted pupil center location and the dilated pupil center location, and therefrom adjusting the laser treatment to be performed on the constricted pupil eye with respect to the vector displacement of the dilated pupil center.
The invention, is directed to a system for diagnostic and therapeutic laser eye treatment where it is intended to align a diagnostic iris image and a treatment iris image via iris pattern recognition techniques to effect a more accurate laser treatment, characterized in that the system includes a controllable, visible illumination component by which a controlled amount of visible illumination can be directed either to the patient's eye being examined or the patient's other eye (not being examined) with the effect of changing in a controlled way the pupil size of the eye under examination. A diagnostic image capture device is used to obtain a sequential plurality of diagnostic iris images, each having a different pupil diameter ranging between a dilated pupil size and a constricted pupil size corresponding to the level of controlled visible illumination. Although, as stated above, an iris recognition landmark present in both the dilated pupil diagnostic iris image and the constricted pupil diagnostic iris image cannot typically be tracked between these two image extremes, at least an indicia of the iris recognition landmark can be tracked through the sequential plurality of diagnostic iris images so that the dilated pupil diagnostic iris image can ultimately be correlated with the constricted pupil diagnostic iris image. The improved system further includes a diagnostic device for obtaining an appropriate diagnostic measurement of the patient's eye wherein this device is cooperatively associated with the illumination control device and the diagnostic image capture device. Further included is a means for exporting at least one of the diagnostic iris images to the laser treatment part of the system, and means for aligning the ultimate constricted pupil diagnostic iris image with the constricted pupil treatment image so that a more accurately positioned laser treatment can be applied to the eye. In an aspect of this embodiment, the means for aligning the plurality of diagnostic iris images and aligning an ultimate diagnostic image with the treatment iris image includes processing hardware and software associated with the treatment part of the system. In an alternative aspect, the alignment means includes processing hardware and software associated with the diagnostic part of the system for sorting and correlating the diagnostic iris images and processing hardware and software associated with the treatment part of the system for aligning the diagnostic iris image and the treatment iris image and, if desired, for adjusting the laser treatment itself. In a preferred aspect of the embodiment, the illumination control device includes a variable illumination fixation target that is an integrated component of the diagnostic measuring device. The image data export means can be any well-recognized method and apparatus for transmitting data from one site to another site, as described in connection with the first disclosed embodiment. In a preferred aspect, the improvement is further characterized by a means for obtaining a vector displacement measurement between the dilated pupil center associated with the dilated pupil diagnostic iris image and the pupil center of the constricted pupil diagnostic iris image. The means more preferably include a limbus landmark referencing to obtain the vector displacement.
These and other objects of the present invention will become more readily apparent from the detailed description to follow. However, it should be understood that the detailed description and specific examples, while indicating the preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the scope of the invention as defined in the claims will become apparent to those skilled in the art.
Figure 4 is a schematic illustration of a device according to a part of the invention;
Figure 1 schematically shows two sequential iris images 10', 10. Image 10 shows an iris area 12, a constricted pupil 14 and typical iris landmarks 16. For the purpose of the description of the invention, the term "constricted pupil" refers to a substantially small pupil size caused by bright light conditions, e.g., eye tracker and fixation light sources along with other environmental conditions present during the treatment phase of laser eye surgery that cause the pupil to constrict. The term constricted pupil, therefore, is not intended to merely describe the smallest possible pupil size that can be induced in a patient's eye, but to describe the smallest working pupil size in accordance with the invention. Iris image 10' shows the same iris 12', however the pupil 14' is dilated and the iris landmarks 16' are shown somewhat obscured due to the dilation of the pupil with respect to iris image 10. The dilated pupil 14', for the purpose of the description of the invention, is due to low light conditions typically associated with diagnostic measurement of the eye, for example, when a wavefront measuring device such as a Zywave™ (Bausch & Lomb/Technolas, Munich, Germany) wavefront measuring device or an Orbscan II® (Orbtek, Salt Lake City, Utah) corneal topographer is used to obtain wavefront aberration information. Thus, the term "dilated pupil" is not intended to refer merely to a maximally dilated pupil that is chemically or artificially induced, but rather to a dark adapted pupil, which is the largest working pupil size associated with this invention. The iris images 10, 10' in Figure 1 are intended to illustrate the changes in form, position and size of naturally occurring landmarks 16, 16' when pupil size changes dramatically (e.g., from dilated to constricted). Under these circumstances, current iris pattern recognition technology has fallen short of being able to match landmark 16 in the constricted pupil condition with landmark 16' in the dilated pupil condition. Therefore, artificial markers on the eye have been used as in tracking points.
Figure 2 shows the diagnostic phase of laser vision surgery in which a patient's wavefront aberration is measured. Wavefront measurements are typically centered about the patient's visual axis or about the center of the patient's dilated pupil. It is advantageous to measure the wavefront aberration over the dilated pupil because certain higher order aberrations manifest their vision compromising effects when the pupil is dark adapted (e.g., night time vision). Iris image 10' schematically shows the patient's iris image during diagnostic measurement, having a dilated pupil 14' and iris landmarks 16'. By controlling the visible illumination to either the patient's eye undergoing examination or the patient's other eye (not undergoing examination), preferably via a variable illumination fixation target in the diagnostic evaluation device, the pupil diameter of the eye being examined can be controlled. With reference to Figure 2, a diagnostic iris image 10' is obtained by a diagnostic iris image capture device with the image 10' corresponding to the pupil diameter during the diagnostic evaluation. The visible illumination level is increased, causing a corresponding decrease in pupil diameter illustrated by 14" in iris image 10". Iris landmarks 16" are also visible having undergone a lesser change than shown in images 10', 10 of Figure 1. As the illumination level is further increased, another diagnostic iris image 10 is obtained which shows a constricted pupil 14 and iris landmarks 16 which, again, have undergone a small and detectable change from landmarks 16" in iris image 10". In this case, the pupil diameter 14 shown in diagnostic iris image 10 will substantially correspond to the pupil diameter of a treatment iris image obtained by a treatment iris image capture device during the treatment phase of the laser vision correction surgery. Diagnostic iris image processing hardware and software can now track the changes in the sequential set of iris images 10', 10", 10 by tracking the landmark indicia so that the iris image 10' associated with the dilated diagnostic pupil 14' can be aligned with the iris image 10 associated with the constricted diagnostic pupil 14. Iris image processing hardware and software connected to a treatment part of the laser system is now used to align a treatment iris image, substantially represented by iris image 10 in Figure 2, with the exported diagnostic iris image 10, allowing the laser ablation treatment pattern directed to the constricted treatment pupil to be accurately aligned with respect to the diagnostic iris image associated with the dilated diagnostic pupil. An advantage of this embodiment wherein the diagnostic iris images are sorted and aligned by the diagnostic stage processing results in the limited data transfer of a single image from the diagnostic phase to the treatment phase.
Since it is known that the rotational orientation of an eye changes when a patient moves from a sitting position to a supine position, the alignment method according to the invention provides appropriate information for rotating the laser ablation treatment pattern to correspond to the cyclo-rotation of the eye. A diagnostic measurement of the patient's eye in the dilated pupil condition is obtained in addition to the diagnostic iris images with the dilated through constricted pupil. As such, the image acquiring apparatus and the diagnostic measurement device may be separate devices, or, these functions may be integrated into a single device. Ultimately a diagnostic measurement will be used by the treatment laser system to calculate the appropriate ablation profile for vision correction. Therefore, it is preferable that the dilated diagnostic measurement be simultaneously associated with the dilated pupil diagnostic iris image. The diagnostic measurement itself will advantageously include the patient's wavefront aberration information which can be directly obtained by a variety of wavefront sensor instruments. One such device is the Zywave wavefront analyzer (Bausch & Lomb/Technolas) which incorporates a Hartmann-Shack wavefront sensor. Other types of devices such as elevation based topographers with ray trace capability such as, e.g., Orbscan II®corneal topography device (Bausch & Lomb/Orbtek, Salt Lake City, Utah) can provide measurement data from which wavefront aberration information can be derived. The diagnostic measurement also preferably includes a measure of the astigmatism.
A system embodiment according to the invention is described with respect to Figure 5. The system 50 is a diagnostic and therapeutic system for laser eye surgery that includes a diagnostic part 52 and a laser treatment part 54. The diagnostic part 52 includes a diagnostic instrument 40 as described with respect to Figure 4 and a diagnostic processor 56 that is programmed to sort, correlate and align the diagnostic iris images as represented in 58. An ultimately aligned constricted pupil diagnostic iris image (as described herein above) is exported from diagnostic part 52 as illustrated by reference 59 via any variety of well-known image data transfer means including land based and wireless communications, computer storage media such as disk or CD, via the Internet or other networks, etc., to laser treatment part 54. Laser treatment part 54 includes a treatment iris image capture device 64 for obtaining the treatment iris image having a constricted pupil of eye 42', a treatment laser 62 and other components such as an eye tracker (not shown). In an alternative aspect of this embodiment, the entire plurality of diagnostic iris images as represented at 58 is exported to treatment part 54 where processing hardware and software represented by processor 66 sorts and correlates the diagnostic iris images and provides the appropriate alignment between the constricted pupil treatment image and the corresponding constricted pupil diagnostic iris image. Processor 66 may also control the calculated laser ablation pattern in response to the iris pattern recognition alignment.
Although preferred embodiments of the present invention have been described in detail herein above, it should be clearly understood that many variations and/or modifications of the basic inventive concepts taught herein which may appear to those skilled in the art, will fall within the scope of the present invention as defined in the appended claims.
A diagnostic and therapeutic system (50) for laser eye surgery comprising an eye diagnostic measuring device (40) for obtaining a diagnostic image (58) of a patient's eye, wherein said diagnostic image of the patient's eye is aligned with a treatment image of the patient's eye that is obtained by a device which is associated with a treatment laser system, via an iris pattern recognition technique,
an illumination control device (48, 49) for controlling a visible illumination level on one of the patient's eye being examined and the patient's other eye (not being examined) wherein the visible illumination level controls the pupil diameter of the examined eye;
means (64) for obtaining a sequential plurality of diagnostic iris images (58) each having a different pupil diameter ranging between a dilated pupil size and a constricted pupil size corresponding to the controlled visible illumination level, and each sequential diagnostic iris image including at least part of an iris recognition landmark (16) the entirety of which is not identifiable between the constricted diagnostic pupil image and the dilated diagnostic pupil image;
means (59) for exporting at least one of the diagnostic iris images to the laser treatment system; and
means (66) for aligning the dilated pupil diagnostic iris image, associated with a diagnostic measurement image, with the constricted pupil diagnostic iris image by tracking using tracking means said sequential plurality of diagnostic iris images; and
The system of claim 1, wherein the means for aligning the dilated pupil diagnostic iris image with the constricted pupil diagnostic iris image includes a diagnostic stage processor cooperatively engaged with a diagnostic image capture device.
The system of any of claims 1 to 2, wherein the means for exporting includes at least one of a wired connection, a wireless connection, a computer file storage medium.
The system of any of claims 1 to 3, wherein the diagnostic measurement obtained by the eye diagnostic measuring device is suitable for obtaining a wavefront information about the patient's eye.
The system of any of claims 1 to 3, wherein the eye diagnostic measuring device includes a iris image capture device.
The system of any of claims 1 to 5, wherein the illumination control device is separate from the diagnostic measuring device.
The system of any of claims 1 to 5, wherein the illumination control device comprises a variable illumination fixation target and is an integrated component of the diagnostic measuring device.
The system of any of claims 1 to 7, further characterized by a means for obtaining a vector displacement measurement between a pupil center of the dilated pupil diagnostic image and the pupil center of the constricted pupil diagnostic image.
The system of any of claims 1 to 7, wherein the vector displacement measurement is a measurement from limbus reference position to the center of the pupil.
The system of any of claims 1 to 9, wherein said diagnostic measuring device is a pupilometer.
The system of any of claims 1 to 9, wherein said diagnostic measuring device is an aberrometer.
The system of any of claims 1 to 9, wherein said diagnostic measuring device is a corneal topographer.
EP1383429A1 EP1383429A1 (en) 2004-01-28
EP1383429B1 true EP1383429B1 (en) 2008-09-17
EP1613215B8 (en) * 2003-04-11 2011-09-14 Bausch & Lomb Incorporated System and method for acquiring data of an eye
ES2296745T3 (en) 2000-04-19 2008-05-01 Alcon Refractivehorizons, Inc. Eye registration control procedure.
2001-05-10 AU AU2001297967A patent/AU2001297967B2/en not_active Ceased