Patent Description:
Reference is made to the documents <NPL>; <CIT>; <CIT>; and <NPL>, <NUM>20th St. Bellingham WA <NUM>-<NUM> USA, which have been cited as relating to the background state of the art. <NPL>" discloses to evaluate negative dysphotopsia by determining ring-shaped shadows in a ray-tracing simulation.

Disclosed herein is a system for predicting post-operative vignetting in an eye of a subject prior to implantation with an intraocular lens. The system includes a controller having a processor and a tangible, non-transitory memory on which instructions are recorded. The controller is in communication with a diagnostic module adapted to store pre-operative anatomic data of the eye as an eye model. The system includes a projection module and a ray tracing module selectively executable by the controller. The projection module is adapted to determine imputed post-operative variables of the eye based at least partially on the pre-operative anatomic data and the intraocular lens. The ray tracing module is adapted to calculate propagation of light through the eye. The controller is configured to obtain the pre-operative anatomic data of the eye, via the diagnostic module. The controller is configured to determine imputed post-operative variables of the eye, via the projection module, and incorporate the imputed post-operative variables into the eye model. The ray tracing module is executed to determine a light distribution for respective visual field angles across a predefined field of view in the eye model. The controller is configured to determine one or more post-operative vignetting parameters based at least partially on the light distribution for the respective visual field angles.

The ray tracing module traces a bundle of rays propagating through the eye. The post-operative vignetting parameters may include a first visual angle defined as a smallest of the respective visual field angles where at least a portion of the bundle of rays passing through a pupil of the eye will not pass through an optical zone of the intraocular lens. The post-operative vignetting parameters may include a second visual angle defined as the smallest of the respective visual field angles where the bundle of rays passing through the pupil will not pass through the optical zone of the intraocular lens. The post-operative vignetting parameters may include a third visual angle defined as the smallest of the respective visual field angles where the bundle of rays passing through the pupil will miss the intraocular lens entirely.

In some embodiments, the pre-operative anatomic data includes an axial length of the eye. The pre-operative anatomic data may include a respective location and a respective profile of an anterior corneal surface and a posterior corneal surface of the eye. The pre-operative anatomic data may include a location, an orientation, and a size of a pupil of the eye in a three- dimensional coordinate system, the pupil being under photopic conditions. The imputed post-operative variables of the eye may include a respective location and a respective orientation of the intraocular lens. The imputed post-operative variables of the eye may include a respective location and a respective orientation of a pupil and/or iris of the eye.

In some embodiments, the ray tracing module is adapted to trace a bundle of rays propagating posteriorly through the intraocular lens until reaching a retina of the eye. The bundle of rays is focused to an infinitesimally small spot on the retina. The ray tracing module may be adapted to employ respective refractive indices in the eye applicable to a wavelength of <NUM> nanometers of light.

Disclosed herein method for predicting post-operative vignetting in an eye of a subject prior to implantation with an intraocular lens, with a system having a controller with a processor and a tangible, non-transitory memory on which instructions are recorded. The method includes adapting a diagnostic module to store pre-operative anatomic data of the eye as an eye model, via at least one imaging device. A projection module is adapted to determine imputed post-operative variables of the eye based at least partially on the pre-operative anatomic data and the intraocular lens, via the controller.

The method includes adapting a ray tracing module to calculate propagation of light through the eye, the ray tracing module being selectively executable by the controller. Pre-operative anatomic data of the eye is obtained, via the diagnostic module. The method includes determining imputed post-operative variables of the eye, via the projection module, and incorporating the imputed post-operative variables into the eye model. The ray tracing module is executed to determine a light distribution for respective visual field angles across a predefined field of view in the eye model. The method includes determining one or more post-operative vignetting parameters based at least partially on the light distribution for the respective visual field angles.

The above features and advantages and other features and advantages of the present disclosure are readily apparent from the following detailed description of the best modes for carrying out the disclosure when taken in connection with the accompanying drawings.

Referring to the drawings, wherein like reference numbers refer to like components, <FIG> schematically illustrates a system <NUM> for predicting parameters related to post-operative vignetting in an eye E, for a subject <NUM> that is a candidate for cataract surgery. It is understood that the drawings are intended to be illustrative and are not drawn to scale. Referring to <FIG>, the system <NUM> includes a controller C having at least one processor P and at least one memory M (or non-transitory, tangible computer readable storage medium) on which instructions are recorded for executing method <NUM>, which is described in detail below with reference to <FIG>. The memory M can store controller-executable instruction sets, and the processor P can execute the controller-executable instruction sets stored in the memory M.

Post-operative vignetting is a partial shadowing in a field of view or image plane occurring in the subject <NUM> after cataract surgery. Vignetting may be described as image dimming or a loss in image brightness perceived by the subject <NUM> and is usually seen at the edges of the image. Vignetting occurs due to light encountering an aperture and becoming partially or totally blocked before reaching the image plane. In some situations, a portion of the incident light is blocked while another portion of the light persists through the optical system. Here, the remaining light continues to form the image but is less bright than it otherwise would be. Post-operative vignetting is associated with negative dysphotopsia, a condition which may require secondary surgical intervention.

<FIG> is a schematic diagram illustrating post-operative vignetting in a pseudophakic eye <NUM>. The pseudophakic eye <NUM> has an intraocular lens <NUM> with an optical zone <NUM>, which is the effective focusing or refractory portion of the intraocular lens <NUM>. Also shown in <FIG> are the anterior corneal surface 206A, posterior corneal surface 206B, pupil <NUM>, iris <NUM>, retina <NUM> and visual axis A. Referring to <FIG>, a beam B enters the pupil <NUM> at a relatively large visual field angle. The pupil <NUM> and iris <NUM> act as a system stop to define the extent of light forming the image perceived by the subject <NUM>. While the entire beam B travels through the pupil <NUM>, some portions of it do not traverse the intraocular lens <NUM>.

Referring to <FIG>, a first beam portion <NUM> of the beam B misses the optical zone <NUM> entirely and passes directly to the retina <NUM> at the first retinal location <NUM>. A second beam portion <NUM> passes through the intraocular lens <NUM> and is focused at a second retinal location <NUM>. Between the first retinal location <NUM> and the second retinal location <NUM> is an intermediate retinal location <NUM> that will not be illuminated at all by the beam B. Although the second retinal location <NUM> is illuminated, it is only partially so because only a fraction of the beam B at this angle is focused by the intraocular lens <NUM>, i.e. the fraction that passes through the optical zone <NUM>.

The combination of the second retinal location <NUM> and the intermediate retinal location <NUM> may be perceived by the subject <NUM> as a dark shadow. This dark shadow may be accentuated by the brighter illumination in the second retinal location <NUM>. In the embodiment shown in <FIG>, the subject <NUM> will perceive the first retinal location <NUM> as occurring at a larger visual field angle than the second retinal location <NUM>, even though the light causing both comes from a single direction.

The system <NUM> (via execution of the method <NUM>) provides an assessment as to the potential severity of vignetting in the pseudophakic eye <NUM> based on pre-operative information. The technical advantage of the system <NUM> is that the clinician will have this information before cataract surgery and may counsel the subject <NUM> appropriately and adjust the treatment plan (e.g., type of implant, implant location, optical power) if appropriate.

As described below, referring to <FIG>, the system <NUM> may include a diagnostic module <NUM> to store pre-operative anatomic data of the eye E. The pre-operative anatomic data may be obtained from at least one imaging device <NUM>. The system <NUM> may include a projection module <NUM> and a ray tracing module <NUM> selectively executable by the controller C. The projection module <NUM> is adapted to predict post-operative anatomic parameters of the eye E based at least partially on the pre-operative anatomic data. The ray tracing module <NUM> is adapted to trace a bundle of rays <NUM> propagating through the pseudophakic eye <NUM>, as described below.

Referring to <FIG>, the system <NUM> may include a user interface <NUM> operable by a user. The user interface <NUM> may include a touchscreen or other input device. The controller C may be configured to process signals to and from the user interface <NUM> and a display (not shown). Additionally, the user interface <NUM> and/or the controller C may be in communication with a lens selection module <NUM>.

The various components of the system <NUM> may be configured to communicate via a network <NUM>, shown in <FIG>. The diagnostic module <NUM>, projection module <NUM> and ray tracing module <NUM> may be embedded in the controller C. Alternatively, the diagnostic module <NUM>, projection module <NUM> and ray tracing module <NUM> may be a part of a remote server or cloud unit accessible to the controller C via the network <NUM>. The network <NUM> may be a bi-directional bus implemented in various ways, such as for example, a serial communication bus in the form of a local area network. The local area network may include, but is not limited to, a Controller Area Network (CAN), a Controller Area Network with Flexible Data Rate (CAN-FD), Ethernet, WIFI, Bluetooth™ and other forms of data connection. Other types of connections may be employed.

Referring now to <FIG>, a flow chart of the method <NUM> for predicting post-operative vignetting in the pseudophakic eye <NUM> is shown. Method <NUM> may be fully or partially executable by the controller C of <FIG>. Method <NUM> need not be applied in the specific order recited herein. Additionally, it is understood that some blocks may be omitted. The method <NUM> begins at block <NUM>.

Per block <NUM> of <FIG>, the controller C is configured to obtain pre-operative anatomic data of the eye E, which may be stored as part of an eye model <NUM> in a diagnostic module <NUM>. The pre-operative anatomic data (which include biometric data) may be obtained from at least one imaging device <NUM>. The imaging device <NUM> may include a topography device, an ultrasound machine, optical coherence tomography machine, a magnetic resonance imaging machine or other imaging device available to those skilled in the art. The pre-operative anatomic data may be derived from a single image or from multiple images.

<FIG> shows a schematic example of a pre-operative image <NUM> of the eye E containing a natural lens <NUM>. The pre-operative image <NUM> may be obtained via an ultrasound bio-microscopy technique. The ultrasound bio-microscopy technique may employ a relatively high frequency transducer of between about <NUM> and <NUM>, with a depth of tissue penetration between about <NUM> and <NUM>. Referring to <FIG>, the pre-operative anatomic data include a respective position, respective orientation, and size of the pupil <NUM> under photopic conditions. Photopic conditions refer to vision under well-lit conditions, which functions primarily due to cone cells in the eye. In some embodiments, photopic conditions may be defined to cover adaptation levels of <NUM> candelas per square meter (cd/m<NUM>) and higher.

Referring to <FIG>, the pre-operative anatomic data include a respective position and respective orientation of the iris <NUM> and natural lens <NUM>. The respective orientation includes a tilt relative to an XYZ coordinate system. The respective positions of the pupil <NUM>, iris <NUM> and natural lens <NUM> may be specified in three dimensions in an XYZ coordinate system; along the X axis as well as along the Y axis and Z axis. The XYZ coordinate system may be defined such that the X axis is parallel to the visual axis A. Alternatively, the XYZ coordinate system may be defined such that the X axis is parallel to another geometrical or optical axis (not shown). Here, the eye model <NUM> would include the position and orientation of the visual axis A.

Referring to <FIG>, the pre-operative anatomic data may include lens thickness <NUM>, anterior chamber depth <NUM> and corneal thickness <NUM>. In addition, the eye model <NUM> in the diagnostic module <NUM> contains the refractive indices of the different portions of the eye E. The pre-operative anatomic data include an axial length <NUM> (shown in <FIG>) of the eye E.

The diagnostic module <NUM> may be selectively executable to approximate or parametrize surfaces in the eye E based on the pre-operative anatomic data and algorithms available to those skilled in the art. The eye model <NUM> of <FIG> may include the shape and location of the anterior corneal surface 306A and the posterior corneal surface 306B (see <FIG>) over the full region where light of interest may enter the eye E. The eye model <NUM> may further include the shape and location of the anterior lens surface <NUM> and the posterior lens surface <NUM> (see <FIG>). The eye model <NUM> may approximate the surface of the retina <NUM> (shown in <FIG>) from the axial length <NUM> as the ocular globe typically has a near spherical shape.

The method <NUM> proceeds to block <NUM> from block <NUM>. Per block <NUM>, the controller C is configured to determine imputed post-operative variables of the eye E, based in part on the pre-operative anatomic data. The imputed post-operative variables may be obtained through a projection module <NUM>. In some embodiments, the projection module <NUM> incorporates intraocular lens power calculation formula available to those skilled in the art such as for example, the SRK/T formula, the Holladay formula, the Hoffer Q formula, the Olsen formula and the Haigis formula. In other embodiments, the projection module <NUM> incorporates a machine learning module, such as a neural network, which is trained to determine the imputed post-operative variables through a large number of historical pairs of pre-operative data and post-operative data. Historical pairs refers to pre-operative data and post-operative data of the same person (e.g., <FIG>). It is understood that the imputed post-operative variables may be obtained from other estimation methods available to those skilled in the art.

<FIG> shows a schematic example of a post-operative image <NUM> of the eye E. Also shown in <FIG> is the intraocular lens <NUM> with supporting structure or haptics <NUM>, anterior corneal surface 406A, posterior corneal surface 406B, pupil <NUM> and iris <NUM>. The imputed post-operative variables include a respective location and a respective orientation or tilt (relative to the XYZ coordinate system) of the intraocular lens <NUM>, the pupil <NUM> and/or the iris <NUM>. Post-operatively, the pupil <NUM> may be decentered or tilted with respect to the visual axis A. In the pre-operative image <NUM>, the iris <NUM> may be bulging and shifted anteriorly (relative to the post-operative image <NUM>) due to the relatively bulkier shape of a natural lens <NUM>. In the post-operative image <NUM>, the iris <NUM> may assume a relatively more planar geometry.

The method <NUM> proceeds to block <NUM> from block <NUM>. Per block <NUM> of <FIG>, the controller C is configured to determine a light distribution across a predefined field of view for the eye E, based on the data obtained in blocks <NUM> and <NUM>. Referring to <FIG>, the predefined field of view may be defined as an arc along the retina <NUM>, between starting retinal location <NUM> and ending retinal location <NUM>. The light distribution may be obtained via the ray tracing module <NUM> (see <FIG>). Referring to <FIG>, the ray tracing module <NUM> (of <FIG>) is adapted to trace a bundle of rays <NUM> propagating through the anterior corneal surface 206A and posterior corneal surface 206B of the pseudophakic eye <NUM>.

The bundle of rays <NUM> of <FIG> are propagated posteriorly through the intraocular lens <NUM> until reaching the retina <NUM>. The ray tracing module <NUM> employs the eye model <NUM> (from block <NUM>) substituted with the imputed post-operative variables obtained in block <NUM> (such as the respective position and respective tilt of the pupil <NUM>, iris <NUM> and intraocular lens <NUM>). Optionally, the ray tracing module <NUM> may assume that effects related to the wave nature of light may be neglected such that the propagation of light is described in terms of rays.

The propagation is traced through reflection and refraction using Snell's law, which describes the refraction of a ray at a surface separating two media with different refractive indices. In other words, as a respective ray in the bundle of rays <NUM> encounters a surface, the new direction of the respective ray is determined in accordance with Snell's law using the refractive indices stored in the diagnostic module <NUM>. In some embodiments, the ray tracing module <NUM> employs refractive indices applicable to <NUM> wavelength of light (green light). The bundle of rays <NUM> is focused to an infinitesimally small spot <NUM> at the retina <NUM> and the spatial distribution of the bundle of rays <NUM> on the retina <NUM> is recorded. The spatial distribution may be represented by a point spread function graph along the retina <NUM>.

The ray tracing module <NUM> provides an assessment of the focusing properties of the pseudophakic eye <NUM> by moving the bundle of rays <NUM> in increments to cover respective visual angles for the predefined field of view. As noted above, the predefined field of view may be defined as an arc along the retina <NUM>, between starting retinal location <NUM> and ending retinal location <NUM>. The light distribution reflects the amount of light hitting the retina <NUM> (making it through) as the incident angle of the bundle of rays <NUM> is varied. In areas of shadowing (such as at high visual angles), the spatial distribution of the bundle of rays <NUM> (represented by a point spread function graph) is flattened and/or bifurcated.

From block <NUM>, the method <NUM> proceeds to block <NUM>. Per block <NUM> of <FIG>, the controller C is configured to determine one or more post-operative vignetting parameters of the pseudophakic eye <NUM> based on the light distribution obtained in block <NUM>. The post-operative vignetting parameters include visual field angles for different regions in the retina <NUM>. Referring to <FIG>, the post-operative vignetting parameters include a first visual angle V1, a second visual angle V2 and a third visual angle V3.

Referring to <FIG>, the first visual angle V1 is defined as the smallest of the respective visual field angles where at least a portion of the bundle of rays <NUM> passing through the pupil <NUM> will not pass through the optical zone <NUM> of the intraocular lens <NUM>. The size of the first visual angle V1 indicates where vignetting likely will first begin. The second visual angle V2 is defined as the as the smallest of the respective visual field angles where the bundle of rays <NUM> passing through the pupil <NUM> will not pass through the optical zone <NUM> of the intraocular lens <NUM>.

The second visual angle V2 indicates where light missing the intraocular lens entirely will be perceived. The third visual angle V3 is defined as the smallest of the respective visual field angles where the bundle of rays <NUM> passing through the pupil <NUM> will miss the intraocular lens <NUM> entirely. The third visual angle V3 indicates where the image perceived by the subject <NUM> may become completely black. The visual angles help to determine the impact of post-operative vignetting on the subject <NUM>, including useful information as to likelihood and potential extent of negative dysphotopsia after cataract surgery.

The method <NUM> proceeds from block <NUM> to block <NUM>. Per block <NUM>, the controller C is configured to determine if the post-operative vignetting parameters obtained in block <NUM> are within respective predefined thresholds, i.e., separate thresholds for each factor. The respective thresholds may be defined or selected based on the application at hand and may vary based on the subject <NUM>. In one example, the respective predefined thresholds are <NUM>, <NUM> and <NUM> degrees, respectively, for the first visual angle V1, the second visual angle V2 and the third visual angle V3.

If the post-operative vignetting parameters are within the respective predefined thresholds, the method <NUM> is ended. If the post-operative vignetting parameters are not within respective predefined thresholds, the method <NUM> may proceed to block <NUM> to determine what modifications may be appropriate. For example, if the size of at least one of the first visual angle V1, the second visual angle V2 and the third visual angle V3 is below the respective predefined thresholds, the surgical plan may be altered to incorporate one or more alternative techniques to lessen the occurrence and/or severity. Because there are tradeoffs involved, the alternative techniques may not normally be pursued.

Referring to <FIG>, the modifications may include decreasing the spacing <NUM> between the iris <NUM> and the intraocular lens <NUM>. A decrease in distance between the body of the intraocular lens <NUM> and iris <NUM> will yield an improvement in vignetting. With an increased spacing <NUM>, the intraocular lens <NUM> encounters less light and the field angle increases.

Referring to <FIG>, the modifications may include using an intraocular lens <NUM> with a larger diameter <NUM>. Increasing the diameter of the intraocular lens <NUM> places lens surfaces in current gaps. In one example, enlarging the diameter <NUM> of the intraocular lens <NUM> from <NUM> to <NUM> pushed the <NUM>% throughput field of view from <NUM> to <NUM> degrees. This is approximately equivalent to moving a <NUM> lens forward by <NUM> microns, in one eye model. The modifications may further include implanting the intraocular lens <NUM> in the sulcus rather than the capsular bag.

If each of the first visual angle V1, the second visual angle V2 and the third visual angle V3 is below the respective threshold, the controller C may be configured to select a different intraocular lens (e.g. different model and/or optical power), via the lens selection module <NUM>, and repeat the steps of the method <NUM>. Additionally, clinicians may offer counselling and manage expectations.

In summary, the system <NUM> inputs pre-operative anatomic data of the eye E about to undergo cataract surgery, predicts various post-operative anatomic parameters and uses ray tracing optical analysis to calculate various parameters related to post-operative vignetting. The system <NUM> may be employed in any procedure where sufficient pre-operative anatomic data is available to allow accurate tracing by the ray tracing module <NUM>.

The controller C of <FIG> includes a computer-readable medium (also referred to as a processor-readable medium), including a non-transitory (e.g., tangible) medium that participates in providing data (e.g., instructions) that may be read by a computer (e.g., by a processor of a computer). Such a medium may take many forms, including, but not limited to, non-volatile media and volatile media. Non-volatile media may include, for example, optical or magnetic disks and other persistent memory. Volatile media may include, for example, dynamic random-access memory (DRAM), which may constitute a main memory. Such instructions may be transmitted by one or more transmission media, including coaxial cables, copper wire and fiber optics, including the wires that comprise a system bus coupled to a processor of a computer. Some forms of computer-readable media include, for example, a floppy disk, a flexible disk, hard disk, magnetic tape, other magnetic medium, a CD-ROM, DVD, other optical medium, punch cards, paper tape, other physical medium with patterns of holes, a RAM, a PROM, an EPROM, a FLASH-EEPROM, other memory chip or cartridge, or other medium from which a computer can read.

Look-up tables, databases, data repositories or other data stores described herein may include various kinds of mechanisms for storing, accessing, and retrieving various kinds of data, including a hierarchical database, a set of files in a file system, an application database in a proprietary format, a relational database management system (RDBMS), etc. Each such data store may be included within a computing device employing a computer operating system such as one of those mentioned above and may be accessed via a network in one or more of a variety of manners. A file system may be accessible from a computer operating system and may include files stored in various formats. An RDBMS may employ the Structured Query Language (SQL) in addition to a language for creating, storing, editing, and executing stored procedures, such as the PL/SQL language mentioned above.

Claim 1:
A system (<NUM>) for predicting post-operative vignetting in an eye of a subject prior to implantation with an intraocular lens, the system comprising:
a controller (C) having a processor (P) and a tangible, non-transitory memory (M) on which instructions are recorded;
a diagnostic module (<NUM>) in communication with the controller, the diagnostic module (<NUM>) being adapted to store pre-operative anatomic data of the eye as an eye model;
a projection module (<NUM>) selectively executable by the controller, the projection module being adapted to determine imputed post-operative variables of the eye based at least partially on the pre-operative anatomic data and the intraocular lens;
a ray tracing module (<NUM>) selectively executable by the controller, the ray tracing module being adapted to calculate propagation of light through the eye; and
wherein the controller (C) is configured to:
obtain (<NUM>) the pre-operative anatomic data of the eye, via the diagnostic module;
determine (<NUM>) imputed post-operative variables of the eye, via the projection module, and incorporate the imputed post-operative variables into the eye model;
execute the ray tracing module to determine (<NUM>) a light distribution for respective visual field angles across a predefined field of view in the eye model; and
determine (<NUM>) one or more post-operative vignetting parameters based at least partially on the light distribution for the respective visual field angles.