Apparatus and method for reducing Purkinje's reflex and haze in a contact-type wide-angle real-time video output fundus imaging system

Abstract

A contact-type eye imaging device includes a light source, an optically transmissive structure optically coupled to the light source and positioned to emit light toward a patient's eye to define an illumination path, one or more optical lenses defining an imaging path, and a first polarizer positioned within the imaging path. The light emitted by the optically transmissive structure may then be polarized to define polarized illumination light. The first polarizer may be configured to at least partially cross-filter polarized illumination light specularly reflected from the patient's eye.

Description

[Technical Field]

[0001] The present invention relates to a system and method for a contact eye imaging system that reduces the Purkinje reflex. [Background technology]

[0002] The present invention relates to ophthalmoscopes, surgical microscopes, and other instruments for viewing and imaging the interior of the human eye. More particularly, the present invention provides an illumination device and system with filtering means that improves illumination efficiency over a wide viewing angle while reducing the Purkinje reflex for diagnostic and documentation purposes of the human eye.

[0003] Conventional contact fundus cameras have used various techniques to reduce the Purkinje reflex. One approach is to place a relatively large-diameter circular light guide behind the contact lens, with a bell-shaped angular power distribution. This causes the illumination beam to interact with the ocular interface near the outside or periphery of the imaging path, where illumination is scarce. An example of such a solution is shown in U.S. Patent No. 5,822,036. The problem with this approach is that illumination is not uniform. Also, the required pupil dilation may exceed what is practically achievable for some infants.

[0004] Another approach is to limit the field of view so that the Purkinje reflex is completely outside the imaging path at the ocular junction. For example, the Phoenix ICON™ system has a field of view of only 100 degrees. This is reflected in U.S. Patent No. 9,872,618. The problem with this approach is that the field of view may not be large enough for some cases of retinopathy of prematurity (ROP).

[0005] Yet another common approach is to digitally remove the Purkinje reflex by sequentially illuminating different regions of the retina and stitching together multiple sequentially captured images, each containing a portion of the image that does not contain the Purkinje reflex. This results in a stitched image that does not contain the Purkinje reflex. See, for example, U.S. Patent No. 10,743,764 and U.S. Patent Application Publication No. 2020 / 0163544. However, this approach has the disadvantage of requiring a higher frame rate, which can result in noticeable delays or make real-time video capture and / or display impossible. Additionally, the stitched frames can exhibit undesirable patterns near overlapping or boundary regions.

[0006] Cross-polarizer approaches have been used in fundus cameras in the past, as shown, for example, in U.S. Patent No. 7,275,826. However, these solutions are not suitable for contact fundus cameras with wide-angle fields of view and real-time video output. Furthermore, the cross-polarizer approach is not recommended in U.S. Patent No. 7,275,826. Summary of the Invention [Problem to be solved by the invention]

[0007] The additional wide-angle lens solution employs two unique illumination beam shaping approaches to significantly improve illumination uniformity on the retina, covering a sufficiently wide and uniform field of view while requiring less pupil dilation than conventional eye imaging systems, such as those shown in U.S. Patent Application Publication Nos. 2021 / 0106222 and 2021 / 0106223. The contents of these patent applications are incorporated herein by reference except to the extent their disclosures conflict with those of this specification. In addition to wide field of view and illumination uniformity, these two unique approaches also reduce the Purkinje reflex by directing the illumination beam reflected from the eyepiece more to the side, away from the imaging path. In many infant eyes, the Purkinje reflex and associated haze are not observable in captured images. However, in eyes with very dark eyes or deep anterior chambers, the Purkinje reflex and associated haze in the eyepiece may be observable even on the dark retina. The present invention improves upon the prior art in that it applies the cross-polarizer approach to a handheld, contact-type, wide-field-of-view, real-time video output fundus imaging system with several specific configurations to produce superior captured video with reduced Purkinje reflection. [Means for solving the problem]

[0008] Summary of the Invention In light of the above, embodiments of the present invention relate to a contact-type eye imaging device that includes a light source, an optically transmissive structure optically coupled to the light source and positioned to emit light toward a patient's eye to define an illumination path, one or more optical lenses defining an imaging path, and a first polarizer positioned within the imaging path. The light emitted by the optically transmissive structure may then be polarized to define polarized illumination light. The first polarizer may be configured to at least partially cross-filter polarized illumination light specularly reflected from the patient's eye.

[0009] In some embodiments, the contact eye imaging device may further include a second polarizer disposed in the illumination path to generate polarized illumination light. The second polarizer may be an annular ring disposed such that the imaging path passes through an opening defined by the second polarizer. In some further embodiments, the contact eye imaging device may further include a contact lens configured to interface with the patient's eye and comprising an interface surface and a non-interfacing surface. The second polarizer may be disposed on the non-interfacing surface of the contact lens.

[0010] In some embodiments, the light-transmitting structure may comprise a plurality of polarizing optical fibers configured to polarize light emitted therefrom, hi some embodiments, the first polarizer may be configured to rotate to change the cross-filter polarization characteristics of the device.

[0011] In a further embodiment, the contact ophthalmic imaging device may further include a fluorescent angiography filter, and may be configured to switch between a first configuration in which the first polarizing optic is positioned in the imaging path and a second configuration in which the fluorescent angiography filter is positioned in the imaging path.

[0012] In some embodiments, the first polarizer can be at least one of a linear polarizer and a circular polarizer. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a side view of a contact ophthalmic imaging device with a lens piece attached to a handpiece according to one embodiment of the present invention; [Figure 2] FIG. 1 is a cross-sectional side view of a lens piece having a circular polarizing optical element according to one embodiment of the present invention. [Figure 3] FIG. 1 is a side cross-sectional view of a lens piece having a circularly polarized contact lens. [Figure 4] FIG. 1 is a cross-sectional side view of a lens piece having a polarizing optical fiber according to one embodiment of the present invention. [Figure 5] 1 is a cross-sectional view showing an illumination path and an imaging path of an imaging system according to an embodiment of the present invention. [Figure 6] 1 is a cross-sectional view showing an illumination path and an imaging path of an imaging system according to an embodiment of the present invention. [Figure 7a] 1 shows the Purkinje reflex produced by use of a conventional contact eye imaging device. [Figure 7b] 1 illustrates the reduction in Purkinje reflex resulting from the use of a contact ophthalmic device according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention will now be described in more detail with reference to the accompanying drawings, which illustrate preferred embodiments of the invention. However, the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Those skilled in the art will understand that the following description of embodiments of the invention is illustrative and not intended to be in any way limiting. Those skilled in the art, having the benefit of this disclosure, will readily suggest other embodiments of the present invention. Like numbers refer to like elements throughout.

[0015] Although the following detailed description contains many specifics for purposes of illustration, those skilled in the art will appreciate that many variations and modifications to the following specifics are within the scope of the present invention. Accordingly, the following embodiments of the present invention are described without any loss of generality to, and without imposing limitations on, the invention.

[0016] In describing the present invention in detail, those skilled in the art should note that directional terms such as "top," "bottom," "upper," "lower," and other similar terms are used for the convenience of the reader referring to the drawings. Those skilled in the art should also note that other terms may be included herein to convey position, orientation, and direction without departing from the principles of the present invention. In particular, "light" may be referred to by various terms herein, such as "illumination," "illumination beam," "visible wavelength," "color," etc.

[0017] Furthermore, those skilled in the art should note that in this detailed description, quantitative modifiers such as "generally," "substantially," "mostly," and other terms are used to generally mean that the object, characteristic, or quality being referred to constitutes the majority of the referenced subject matter. The meaning of these terms depends on the context in which they are used, and their meanings may be expressly modified.

[0018] As shown and described by the various figures and accompanying text, one embodiment of the present invention provides a handheld, contact-type eye imaging device 100. The eye imaging device 100 may be configured to interface with the cornea of ​​a patient's eye to provide real-time, wide-angle fundus imaging and video capture. The eye imaging device 100 may include a lens piece 110 attached to a hand piece 120. The lens piece 110 may be removably attached to the hand piece 120, allowing various lens pieces to be attached to the hand piece 120. The hand piece 120 may include a light emitting device. When attached, the lens piece 110 may be positioned in optical communication with the hand piece 120, such that light generated by the light emitting device of the hand piece 120 may travel along an illumination path of the lens piece 110 and propagate along an imaging path of the lens piece 110 to the hand piece 120. The hand piece 120 may further include an imaging device operable to collect and measure light received from the lens piece 110 and generate a real-time video signal therefrom.

[0019] Referring to FIG. 2 , a cross-sectional side view of a lens piece 200 according to one embodiment of the present invention is shown. The lens piece 200 comprises a housing 202, an optically transmissive structure 210, a contact lens 230, and a polarizer 220. The optically transmissive structure 210 may be configured to receive light from a light-emitting device of the hand piece 120 at a first end 212, propagate through a length 214 of the optically transmissive structure 210, and emit from a second end 216 thereof. The optically transmissive structure 210 may comprise one or more structures operable to receive, transmit, and emit light as previously described, including, but not limited to, an optical waveguide such as an optical fiber, a transparent dielectric waveguide made of plastic or glass, a light pipe, etc. While two optically transmissive structures 210 are shown in FIG. 2 , it is contemplated and within the scope of the present invention that any number of structures may collectively define the optically transmissive structure 210. Additionally, the various structures of optically transmitting structure 210 may be positioned and distributed in a manner that may be advantageous to improve illumination of the patient's eye, examples of which are shown in U.S. Patent Application Publication Nos. 2021 / 0106222 and 2021 / 0106223. Additionally, optically transmitting structure 210 may be configured to transmit light within a selected wavelength range, such as the visible spectrum (wavelengths ranging from 400 nanometers (nm) to 700 nm), the infrared spectrum (700 nm to 1000 nm), and the ultraviolet spectrum (10 nm to 400 nm), as well as any portion thereof.

[0020] Light may be emitted from the second end 216 of the optically transmitting structure 210 and propagate along the illumination path 206 into the patient's eye 204. In some embodiments, the lens piece 200 may include an illumination path polarizer 220 disposed between the second end 216 of the optically transmitting structure 210 and the patient's eye 204. In some embodiments, the illumination path polarizer 220 may be disposed intermediate the second end 216 of the optically transmitting structure 210 and a contact lens 230 of the lens piece 200, the contact lens 230 being configured to interface with the patient's eye 204. Placing the illumination path polarizer 220 in this position may polarize a majority of the light emitted from the optically transmitting structure 210, thereby efficiently polarizing the light required for retinal imaging. The illumination path polarizer 220 may be a separate structure disposed adjacent the second end 216 of the optically transmitting structure 210 and the contact lens 230, but in some embodiments, it may be operable and replaceable independently of the optically transmitting structure 210 and the contact lens 230.

[0021] Contact lens 230 may be generally transparent and may pass all light of all polarizations. Additionally, in some embodiments, contact lens 230 may avoid absorbing, reflecting, or refracting light passing therethrough, thereby avoiding changing the optical properties of the light passing therethrough.

[0022] The shape of illumination path polarizer 220 may reflect the configuration of light transmission structure 210. In this embodiment, if the light transmission structure includes a plurality of structures arranged such that their second ends 216 define a ring-shaped array, illumination path polarizer 220 may be annular. In a similar embodiment, if light transmission structure 210 is an annular light guide, illumination path polarizer 220 may likewise be annular.

[0023] The annular illumination path polarizer 220 may allow polarization of light passing through the illumination path polarizer while simultaneously allowing light reflected from the patient's eye 204 to pass through an opening 222 defined by the illumination path polarizer along the imaging path, as will be described in more detail below. However, it is contemplated and within the scope of the present invention that the illumination path polarizer 220 may take any shape that may or may not match the shape of the second end 216 of the light-transmitting structure 210.

[0024] The polarization of the illumination path polarizer 220 can be linear or circular or elliptical. If the illumination path polarizer 220 is a linear polarizer, the plane of polarization passing therethrough can be changed by rotating the illumination path polarizer 220. In some embodiments, the illumination path polarizer 220 can be manipulated by an operator to rotate the illumination path polarizer 220 before, during, or after operation of the ocular imaging device 100. Such manipulation can change the cross-polarization with the imaging path polarizer, as described below.

[0025] Polarized light from the illumination path polarizer, defined as polarized illumination light, may be reflected by the patient's eye 204 along the imaging path and pass through aperture 222, as described above. Such light may specularly reflect from the front and / or rear junctions of the eyepiece. In addition to the contact lens, lens piece 200 may further include one or more imaging path optical lenses 240, the central region of which also functions as one of the imaging path lenses. Imaging path optical lens 240 may be configured to modify the optical properties of light reflected from the patient's eye 204. Additional details regarding imaging path optical lenses may be found in the above-referenced U.S. Patent Application Publication Nos. 2021 / 0106222 and 2021 / 0106223.

[0026] Lens piece 200 may further include an imaging path polarizer 250. The imaging path polarizer 250 may be configured to at least partially cross-filter reflected light from the patient's eye 204. The reflected light may be specularly reflected from the patient's eye. Additionally, the reflected light may already be polarized, for example, by illumination path polarizer 220. The polarization direction of imaging path polarizer 250 may be oriented, in the case of linear polarization, so that the planes defining the polarization of polarizers 220 and 250 are not parallel, i.e., form an angle defined as the relative orientation angle. In some embodiments, the relative orientation angle may range from 0 degrees to 180 degrees, greater than 0 degrees but less than 180 degrees, and permutations thereof. After cross-polarizing the reflected light, imaging path polarizer 250 may be configured to mitigate Purkinje reflections present in the reflected light while maintaining the fidelity of the anatomical features of the patient's eye 204 shown in the image represented by the light in the imaging path.

[0027] In some embodiments, imaging path polarizer 250 may be configured to further define an optical protection window, whereby the internal structure of lens piece 200 may be protected from environmental contaminants by imaging path polarizer 250. Additionally, in some embodiments, imaging path polarizer 250 may be configured to be manipulated by a user to change the orientation angle of the polarized light relative to illumination path polarizer 220, as described above. For example, the imaging path polarizer may be configured to rotate with respect to illumination path polarizer 220, thereby changing the relative orientation angle.

[0028] Referring to FIG. 3 , a lens piece 300 according to one embodiment of the present invention is shown. Lens piece 300 may include an optically transmissive structure 310 and a contact lens 330, as described above. Furthermore, contact lens 330 may include an interface surface 332 configured to interface with a patient's eye 304 and a non-interfacing surface 334 located generally opposite interface surface 322. In this embodiment, illumination path polarizer 320 may be attached onto non-interfacing surface 324 of contact lens 330. Such attachment may be achieved by any means or method known in the art. In some embodiments, illumination path polarizer 320 may be a film adhered to non-interfacing surface 324 by any means or method known in the art.

[0029] Referring to Figure 4, a lens piece 400 according to one embodiment of the present invention is shown. In this embodiment, the optically transmissive structure 410 is configured to polarize light emitted from the second end 416, thereby eliminating the need for a separate illumination path polarizer. Such polarization can occur at any point along the optically transmissive structure, such as at the first end 412, the strip 414, or the second end 416.

[0030] 5 illustrates the illumination and imaging paths of an imaging system according to one embodiment of the present invention. The eye imaging device 500 includes a light source 502, a hand piece 510, and a lens piece 520. The light source 502 may be any device operable to generate light within the eye imaging spectrum, such as the visible spectrum, necessary to perform eye imaging, including, but not limited to, a light emitting diode (LED), an organic LED, an incandescent lighting device, a halogen lighting device, a fluorescent lighting device, etc. The light source 502 may be located inside or outside the housing of the hand piece 510.

[0031] The handpiece 510 may include an image sensor 512. The image sensor 512 may be configured to connect to a live video display (not shown) to present a video image of light received by the image sensor 512 along the imaging path 511 to a user. Any type of image sensor known in the art is within the scope of the present invention, including, but not limited to, a charge-coupled device (CCD), a CMOS device, an NMOS device, or hybrids thereof. The handpiece 510 may further include a color splitter prism block or optical path length correction block 513 positioned optically in front of the image sensor 512 along the imaging path 511. The handpiece 510 may further include a deep red and / or near infrared cut filter 514 positioned optically in front of the block 513 along the imaging path 511. The handpiece 510 may further include an axially movable lens combination 515 positioned optically in front of the filter 514 along the imaging path 511. Details of the axially movable lens combination are described in the above-referenced U.S. Patent Application Publication Nos. 2021 / 0106222 and 2021 / 0106223.

[0032] The handpiece 510 may further include an imaging path selection device 516. The imaging path selection device 516 may be configured to allow a user to position the device 516 in one of at least two orientations to selectively position one of at least two optical elements in the imaging path 511. The first optical element may be an imaging path cross polarizer 517, as described above, which may be positioned in the imaging path 511 when the device 516 is in the first orientation. By including this imaging path polarizer 517 in the handpiece, the aforementioned imaging path polarizer 250 shown in FIG. 2 may be unnecessary. The second optical element may be a bandpass filter 518 configured to transmit light within a wavelength range, which may be positioned in the imaging path 511 when the device 516 is in the second orientation. In this embodiment, the bandpass filter 518 may be configured to transmit light in the green wavelength range, for example, light having a peak wavelength in the range of 490 nm to 570 nm. Such a range may be useful for performing fluorescein angiography. This range is merely exemplary, and any range is contemplated and included within the scope of the present invention. Additionally, device 516 may include multiple bandpass filters, each with a different transmittable wavelength range.

[0033] The hand piece 510 may further include a hand piece optically transmitting structure 519 optically coupled to the light source 502 and the optically transmitting structure 522 of the lens piece 520, respectively, and configured to transmit light from the light source 502 to the optically transmitting structure 522.

[0034] Referring to Figure 6, a cross-sectional view of an eye imaging device 600 according to one embodiment of the present invention is shown. The eye imaging device 600 may be substantially similar to the eye imaging device 500 of Figure 5, except for the imaging path selection device 516. In this embodiment, the eye imaging device 600 includes a handpiece 610 with an imaging path polarizer 612 in an imaging path 611. The imaging path polarizer 612 may be configured to be rotated by a user to change the relative orientation angle between the imaging path polarizer and the illumination path polarizer 622 of the lens piece 620 of the eye imaging system 600, as described above. In such an embodiment, the imaging path polarizer 612 may be a linear polarizer.

[0035] Referring to Figures 7a and 7b, imaging of a patient's eye model 700 using the above-described invention is shown. Figure 7a shows a patient's eye model 700' without the use of cross-polarized light as described in the above embodiment of the invention, with a substantial Purkinje reflex 702' that is very noticeable and obscures much of the anatomy of the patient's eye 700'. Figure 7b shows the same patient's eye model 700'' with the application of the above-described cross-polarized light, with a significant reduction in the Purkinje reflex 702' and much clearer visibility of the previously obscured anatomy.

[0036] Some of the exemplary aspects of the present invention may be advantageous in solving the problems described herein, as well as other problems not described herein that may be discoverable by one of ordinary skill in the art.

[0037] While the above description contains many specific details, these should not be construed as limiting the scope of the embodiments, but as illustrative of the presented embodiments. Many other variations and modifications are possible within the scope of the teachings of the various embodiments. While the present invention has been described with reference to exemplary embodiments, those skilled in the art will recognize that various changes may be made without departing from the scope of the invention and that equivalents may be substituted for elements thereof. Furthermore, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope of the invention. Therefore, the present invention is not limited to the particular embodiment disclosed as the best or only mode contemplated for carrying out the invention, but is intended to include all embodiments falling within the description of the invention. Furthermore, although the drawings and description disclose exemplary embodiments of the invention and specific terms may be used, unless otherwise noted, these terms are used in a generic and descriptive sense only and not for purposes of limitation, and therefore do not limit the scope of the invention in any way. Furthermore, the use of terms such as "first," "second," etc., does not denote any order or importance, but rather is used to distinguish one element from another. Furthermore, the use of terms such as "a," "an," etc. does not denote a limitation of quantity, but rather denotes the presence of at least one of the referenced item.

Claims

1. A contact-type eye imaging device, comprising: A light source and a light-transmitting structure optically coupled to the light source and positioned to emit light toward the patient's eye to define an illumination path; one or more optical lenses defining an imaging path; a first polarizer disposed in the imaging path; the light emitted by the light-transmitting structure is then polarized to define polarized illumination light; and A contact eye imaging device, wherein the first polarizer is configured to at least partially cross-filter polarized illumination light specularly reflected from the patient's eye.

2. The contact eye imaging device of claim 1 , further comprising a second polarizer disposed in the illumination path to generate the polarized illumination light.

3. The contact eye imaging device of claim 2 , wherein the second polarizer is an annular ring positioned such that the imaging path passes through an opening defined by the second polarizer.

4. 3. The contact eye imaging device of claim 2, further comprising a contact lens configured to interface with the patient's eye and having an interface surface and a non-interfacing surface, the second polarizer being disposed on the non-interfacing surface of the contact lens.

5. The contact eye imaging device of claim 1 , wherein the light-transmitting structure comprises a plurality of polarizing optical fibers configured to polarize light emitted therefrom.

6. A contact eye imaging device according to any preceding claim, wherein the first polariser is configured to rotate to change the cross-filter polarisation characteristics of the device.

7. A contact eye imaging device described in any one of claims 1 to 6, further comprising a fluorescent angiography filter, and the device is configured to switch between a first configuration in which the first polarizing optical system is positioned in the imaging path and a second configuration in which the fluorescent angiography filter is positioned in the imaging path.

8. The contact eye imaging device according to any one of claims 1 to 7, wherein the first polarizer is at least one of a linear polarizer and a circular polarizer.

9. A contact-type eye imaging device, comprising: A light source and a light-transmitting structure optically coupled to the light source and positioned to emit light toward the patient's eye to define an illumination path; one or more optical lenses defining an imaging path; a first polarizer disposed in the imaging path, the first polarizer being at least one of a linear polarizer and a circular polarizer; a second polarizer disposed in the illumination path to polarize the light emitted by the light-transmitting structure to produce polarized illumination light; A contact eye imaging device, wherein the first polarizer is configured to at least partially cross-filter polarized illumination light specularly reflected from the patient's eye.

10. 10. The contact eye photography device of claim 9, wherein the second polarizer is an annular ring positioned such that the imaging path passes through an opening defined by the second polarizer.

11. 11. The contact eye imaging device of claim 10, further comprising a contact lens configured to interface with the patient's eye and having an interface surface and a non-interfacing surface, the second polarizer being disposed on the non-interfacing surface of the contact lens.

12. A contact eye photography device according to any one of claims 9 to 11, wherein the first polarizer is configured to rotate to change the cross-filter polarization characteristics of the device.

13. A contact eye imaging device described in any one of claims 9 to 12, further comprising a fluorescent angiography filter, and the device is configured to switch between a first configuration in which the first polarizing optical system is positioned in the imaging path and a second configuration in which the fluorescent angiography filter is positioned in the imaging path.

14. A contact-type eye imaging device, comprising: A light source and an optically transmissive structure optically coupled to the light source, the optically transmissive structure comprising a plurality of polarized optical fibers, the optically transmissive structure positioned to emit polarized illumination light toward the patient's eye to define an illumination path; one or more optical lenses defining an imaging path; a first polarizer disposed in the imaging path; A contact eye imaging device, wherein the first polarizer is configured to at least partially cross-filter polarized illumination light specularly reflected from the patient's eye.

15. 15. The contact eye photography device of claim 14, wherein the first polarizer is configured to rotate to change the cross-filter polarization characteristics of the device.

16. 16. A contact eye imaging device as described in any one of claims 14 or 15, further comprising a fluorescent angiography filter, the device being configured to switch between a first configuration in which the first polarizing optical system is positioned in the imaging path and a second configuration in which the fluorescent angiography filter is positioned in the imaging path.

17. The contact eye imaging device according to any one of claims 14 to 16, wherein the first polarizer is at least one of a linear polarizer and a circular polarizer.

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