Patent Description:
Vision impairments such as myopia (near-sightedness), hyperopia and astigmatism can be corrected using eyeglasses or contact lenses. Alternatively, the cornea of the eye can be reshaped surgically to provide the needed optical correction. Eye surgery has become commonplace with some patients pursuing it as an elective procedure to avoid using contact lenses or glasses to correct refractive problems, and others pursuing it to correct adverse conditions such as cataracts. And, with recent developments in laser technology, laser surgery is becoming the technique of choice for ophthalmic procedures.

Different laser eye surgical systems use different types of laser beams for the various procedures and indications. These include, for instance, ultraviolet lasers, infrared lasers, and near-infrared, ultra-short pulsed lasers. Ultra-short pulsed lasers emit radiation with pulse durations as short as <NUM> femtoseconds and as long as <NUM> nanoseconds, and a wavelength between <NUM> and <NUM>.

Prior surgical approaches for reshaping the cornea include laser assisted in situ keratomileusis (hereinafter "LASIK"), photorefractive keratectomy (hereinafter "PRK") and Small Incision Lens Extraction (hereinafter "SmILE"). In the SmILE procedure, instead of ablating corneal tissue with an excimer laser following the creation of a corneal flap, the technique involves tissue removal with two femtosecond laser incisions that intersect to create a lenticule for extraction. The extraction of the lenticule changes the shape of the cornea and its optical power to accomplish vision correction. Lenticular extractions can be performed either with or without the creation of a corneal flap. With the flapless procedure, a refractive lenticule is created in the intact portion of the anterior cornea and removed through a small incision.

<CIT> describes a planning system for generating control data wherein the system includes a processor configured to specify cornea incision surfaces including a lenticule incision and a cap incision, at least one of which incision being irregularly shaped and having extensions to the surrounding tissue.

To obviate one or more problems due to limitations and disadvantages of the related art, embodiments of the present invention provide an ophthalmic surgical laser system for forming a lenticule in a cornea of a patient's eye for extraction, the system including: a laser system configured to generate a pulsed laser beam; an optical delivery system configured to deliver the published laser beam to a cornea of a patient's eye, including a scanner system configured to scan a focus spot location of the pulsed laser beam within the cornea; a controller configured to control the laser system and the scanner system to: scan the focus spot location of the pulsed laser beam within the cornea to form a top lenticule surface incision in the cornea; and scan the focus spot location of the pulsed laser beam within the cornea to form a bottom lenticule surface incision in the cornea, wherein the top and bottom lenticule surface incisions intersect each other to form a volume of corneal tissue between them, and wherein the volume of corneal tissue includes a lenticular portion having a circular or oval shape in a top view, and a side tab portion connected to the lenticular portion and protrudes from a peripheral location of the lenticular portion, wherein the side tab portion has a defined thickness profile in a side cross-sectional view.

Corneal lenticule extraction methods are described for illustrative purposes only and do not form a part of the claimed invention.

This summary and the following detailed description are merely exemplary, illustrative, and explanatory, and are not intended to limit, but to provide further explanation of the invention as claimed. Additional features and advantages of the invention will be set forth in the descriptions that follow, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description, claims and the appended drawings.

A better understanding of the features and advantages will be facilitated by referring to the following detailed description that sets forth illustrative embodiments using principles of the invention, as well as to the accompanying drawings, in which like numerals refer to like parts throughout the different views. Like parts, however, do not always have like reference numerals. Further, the drawings are not drawn to scale, and emphasis has instead been placed on illustrating the principles of the invention. All illustrations are intended to convey concepts, where relative sizes, shapes, and other detailed attributes may be illustrated schematically rather than depicted literally or precisely.

Embodiments of this invention are generally directed to systems for laser-assisted ophthalmic procedures, and more particularly, to systems for corneal lenticule formation and extraction. More specifically, the corneal lenticule is formed with a generally circular or oval shape with a side tab that protrudes from the periphery of the lenticule to assist in easy extraction of the lenticule from the cornea.

<FIG>, <FIG>, <FIG>, <FIG> schematically illustrate the shape of a corneal lenticule according to embodiments of the present invention. <FIG> is a top (front) view showing the eye, the cornea, and the lenticule having a side tab (extraction tab), viewed in a direction parallel to the optical axis O of the eye. <FIG> and <FIG> are side cross-sectional views of the lenticule in respective planes passing through the optical axis O, viewed in the directions 2A-2A' and 2B-2B' of <FIG>, respectively. The cross-section shown in <FIG> does not include the side tab, and the cross-section shown in <FIG> includes the side tab.

In <FIG> and <FIG>, the vertical direction is the depth direction of the eye, parallel to the optical axis O, and the horizontal direction is referred to as the transverse direction. The cornea from which the lenticule is incised and extracted is not shown in <FIG> and <FIG>. In this embodiment, the incisions are performed while the cornea is flattened (applanated) by a contact lens (not shown) of a patient interface device of the laser system which presses against and flattens the cornea.

As shown in <FIG>, the lenticule <NUM> preferably has a circular or oval shape in the top view, except for the side tab that protrudes from a peripheral location of the lenticule. As shown in <FIG>, the lenticule <NUM> is formed by a top lenticular incision surface D-C-C'-D' and a bottom lenticular incision surface B-A-A'-B', which intersect each other at the peripheral edge of the lenticule, shown as points G and G' in the cross-sectional view. The intersecting top and bottom surfaces form an isolated volume of the cornea which constitutes the lenticule. Preferably, the end points D and B of the top and bottom edge transition portions CD and AB extend beyond the intersection point G of the two edge transition portions. This helps to ensure that the lenticule is fully separated from the cornea, so that the extraction can be done free of tissue-bridges and minimal or no unwanted residual tissue pieces are left inside the cornea.

In the illustrated embodiment, both top and bottom surfaces are convex, and the lenticule is a convex lens shape. Extracting this lenticule from the cornea effectuates a myopia correction of the eye.

Each of the top and bottom lenticular surfaces has a spherical portion CC' or AA' at the center, referred to as the optical zone, and a peripheral portion CD and C'D' or AB and A'B' that extends beyond the spherical portion, referred to as the edge transition zone. In the top view, the spherical portion preferably has a circular or oval shape and the edge transition zone has a circular or oval ring shape that surrounds the spherical portion. In the top view, the top and bottom spherical portions overlap each other and the top and bottom edge transition portions overlap each other. While each of the top and bottom spherical portions CC' and AA' is a part of a sphere, the respective edge transition zone is not located on the same sphere of the spherical portion but rather, has a steeper shape in the side cross-sectional view than the sphere. In other words, each edge transition zone is located inside of the volume defined by the sphere of the corresponding spherical portion. Thus, the distance from the optical axis O of the lenticule to the intersection point G, where the top edge transition portion CD and the bottom edge transition portion AB intersect each other, is smaller than the distance from the optical axis O to the imaginary intersection point H' where the two spheres that define the spherical portions CC' and AA' intersect each other, as shown in <FIG>. In <FIG>, the two intersection points are illustrated on the right-hand side edge of the lenticule <NUM> and labeled G' and H', respectively, where OG' < OH'.

In some embodiments, the radial dimension of transition zone is approximately <NUM> - <NUM>, depending on size of optical zone.

The provision of the transition zone is optional. In other words, the entire top and bottom lenticule surfaces D-C-C'-D' and B-A-A'-B' may be spherical surfaces forming the optical zone.

The side tab of the lenticule is formed to assist in easy extraction of the lenticule from the cornea. As shown in <FIG> and <FIG>, the side tab is located at a defined angular position along the periphery of the lenticule, preferably temporally located (i.e. on the temple side) for easier access, but may alternatively be located anywhere along the periphery of the lenticule. In some embodiments, the side tab is substantially rectangular in the top view (<FIG>) with a size of approximately <NUM> - <NUM> in the radial direction of the lenticule and approximately <NUM> - <NUM> in the angular direction of the lenticule. The size of the side tab is chosen based on considerations of the size of the lenticule (which is typically <NUM> to <NUM> in diameter including the transition zone) and the sizes of the extraction tool. In alternative embodiment, the side tab may have a slightly tapered shape in the top view, being narrower at the outer edge. In the side cross-sectional plane that passes through the optical axis O (<FIG>), the side tab has a profile that has a generally tapered thickness and a rounded outer edge.

The side tab is formed by a top side tab surface which is a part of the top lenticule surface and is smoothly connected to the rest of the top lenticule surface (e.g. the edge transition zone), and a bottom surface which is a part of the bottom lenticule surface and is smoothly connected to the rest of the bottom lenticule surface (e.g. the edge transition zone), the top and bottom side tab surfaces intersecting each other to form the outer edge of the side tab. As described earlier, the edge transition zones has a steeper shape in the side cross-sectional view than the sphere of the optical zone; in the area corresponding to the side tab, however, the edge transition zones is made less steep than the sphere, and the top and bottom side tab surfaces continue to extend outwardly beyond where the imaginary intersection point of the top and bottom spheres.

In a cross-section cutting through the side tab by a plane that is parallel to the optical axis O (see the line with arrows 2C-2C' in <FIG>) and tangential to the peripheral circle of the lenticule (see the line with arrows 2C-2C' in <FIG>), the side tab may have a substantially oval shape, as shown in the example of <FIG>, or a shape with substantially flat top and bottom and rounded sides, as shown in the example of <FIG>, of a shape with concave top and bottom and rounded sides (not shown in drawings), or other suitable shapes.

As shown in the examples in <FIG>, <FIG>, the top and bottom side tab surfaces preferably extend beyond where they intersect each other, which helps to ensure that the side tab is fully separated from the cornea.

Preferably, the entire top lenticular surface, including the top side tab surface, is a smooth surface and the entire bottom lenticular surface, including the bottom side tab surface, is a smooth surface. This reduces tissue step formation in the cornea after the lenticule is extracted.

In corneal lenticule extraction procedures, an entry cut is also formed to provide an access of extraction tools and a passage for lenticule removal. The entry cut is typically a band shape which extends from the anterior cornea surface to the top (or bottom) lenticule surface at a location within the transition zone, as shown in <FIG> and <FIG>. The intersection line of the entry cut with the top (or bottom) lenticule surface is typically an arc shape as schematically shown by the dashed arc in <FIG>. In the top view, the angular position of the intersection of the entry cut with the top or bottom lenticule surface is preferably in a vicinity of the side extraction tab, for example, with a gap of less than a few mm between them. The entry cut and the side tab may also overlap each other in the top view.

In a corneal lenticule extraction procedure, after forming the top and bottom lenticule surfaces including the side tab, and the entry cut, the surgeon inserts a surgical tool, such as a surgical spatula or surgical tweezers, through the entry cut, to separate the lenticule tissue at the top and bottom lenticule surfaces from the remaining cornea tissue. The surgeon then uses the same or another surgical tool to grab the side tab and extract the lenticule from the cornea through the entry cut.

In the embodiment sown in <FIG> and <FIG>, both top and bottom surfaces are convex. In alternative embodiments, one or both of the top and bottom surfaces may be concave, and the lenticule maybe a convex or concave lens shape. For example, in the lenticule shown in <FIG>, both the top and the bottom surfaces are concave and the lenticule is a concave lens shape.

Formation of a corneal lenticule without a side extraction tab is described in co-pending <CIT>, entitled Systems and Methods for Lenticular Laser Incision, and <CIT>, entitled Ophthalmic Laser Surgical System and Method for Corneal Lenticular Incisions with Unambiguous Entry Cuts. For a corneal lenticule formed without a side tab, extraction of the lenticular tissue is sometimes difficult. Surgeons typically use surgical tweezers to remove the lenticule. During extraction, the transition zone outside of the optical zone may be grabbed to extract the corneal tissue. However, there is a risk of the surgical tool crossing into the optical zone, which may be detrimental. On the other hand, too large of a transition zone may lead to a higher probability of fragmented tissue separating from the lenticule during extraction, as well as unnecessary removal of extra corneal tissue.

Therefore, in embodiments of the present invention, an added side extraction tab is integrated into the transition zone in the cutting pattern of the lenticule, to allow for a larger area to pull the tissue without crossing into the optical zone, while avoiding excessive removal of corneal tissue. The side tab may improve speed of extraction, as well as completeness of extraction, i.e., to leave no lenticule tissue behind.

In the embodiments described above, the various incisions in the cornea may be performed using any suitable ophthalmic laser system. Described generally, such a laser surgical system includes a laser source for generating a pulse laser beam, an optical system for delivering the laser beam to a target tissue in the eye to form a focus spot therein, the optical system including a scanner system to scan the laser focus spot position in three dimensions, and a controller connected to above components to control and operate them. The laser surgical system preferably also includes measurement and imaging systems to measure and image the structure of the eye. The control system may include a processor executing computer-readable program code stored in a memory, where the program code causes the processor to control the scanner system to scan the laser focus spot according to pre-programed scan patterns to form the various incisions described above.

A laser system that may be used to form the various incisions in embodiments of the present invention is described in more detail below with reference to <FIG> and <FIG>.

<FIG> shows a system <NUM> for making an incision in a material <NUM> such as the cornea. The system <NUM> includes, but is not limited to, a laser <NUM> capable of generating a pulsed laser beam <NUM>, an energy control module <NUM> for varying the pulse energy of the pulsed laser beam <NUM>, a Z-scanner <NUM> for modifying the depth of the pulse laser beam <NUM>, a controller <NUM>, a prism <NUM> (e.g., a Dove or Pechan prism, or the like), and an XY-scanner <NUM> for deflecting or directing the pulsed laser beam <NUM> from the laser <NUM> on or within the material <NUM>. The controller <NUM>, such as a processor executing suitable control software, is operatively coupled with the Z-scanner <NUM>, the XY-scanner <NUM>, and the energy control unit <NUM> to direct a scan line <NUM> of the pulsed laser beam along a scan pattern on or in the material <NUM>. In this embodiment, the system <NUM> further includes a beam splitter <NUM> and a detector <NUM> coupled to the controller <NUM> for a feedback control mechanism (not shown) of the pulsed laser beam <NUM>. Other feedback methods may also be used, including but not necessarily limited to position encoder on the scanner <NUM>, or the like. In an embodiment, the pattern of pulses may be summarized in machine readable data of tangible storage media in the form of a treatment table. The treatment table may be adjusted according to feedback input into the controller <NUM> from an automated image analysis system in response to feedback data provided from an ablation monitoring system feedback system (not shown). Optionally, the feedback may be manually entered into the controller <NUM> by a system operator. The feedback may also be provided by integrating a wavefront measurement system (not shown) with the laser surgery system <NUM>. The controller <NUM> may continue and/or terminate a sculpting or incision in response to the feedback, and may also modify the planned sculpting or incision based at least in part on the feedback. Measurement and imaging systems are further described in <CIT> and <CIT>.

In an embodiment, the system <NUM> uses a pair of scanning mirrors or other optics (not shown) to angularly deflect and scan the pulsed laser beam <NUM>. For example, scanning mirrors driven by galvanometers may be employed where each of the mirrors scans the pulsed laser beam <NUM> along one of two orthogonal axes. A focusing objective (not shown), whether one lens or several lenses, images the pulsed laser beam <NUM> onto a focal plane of the system <NUM>. The focal point of the pulsed laser beam <NUM> may thus be scanned in two dimensions (e.g., the x-axis and the y-axis) within the focal plane of the system <NUM>. Scanning along the third dimension, i.e., moving the focal plane along an optical axis (e.g., the z-axis), may be achieved by moving the focusing objective, or one or more lenses within the focusing objective, along the optical axis.

Laser <NUM> may comprise a femtosecond laser capable of providing pulsed laser beams, which may be used in optical procedures, such as localized photodisruption (e.g., laser induced optical breakdown). Localized photodisruptions can be placed at or below the surface of the material to produce high-precision material processing. For example, a micro-optics scanning system may be used to scan the pulsed laser beam to produce an incision in the material, create a flap of the material, create a pocket within the material, form removable structures of the material, and the like. The term "scan" or "scanning" refers to the movement of the focal point of the pulsed laser beam along a desired path or in a desired pattern.

In other embodiments, the laser <NUM> may comprise a laser source configured to deliver an ultraviolet laser beam comprising a plurality of ultraviolet laser pulses capable of photodecomposing one or more intraocular targets within the eye.

Although the laser system <NUM> may be used to photoalter a variety of materials (e.g., organic, inorganic, or a combination thereof), the laser system <NUM> is suitable for ophthalmic applications in some embodiments. In these cases, the focusing optics direct the pulsed laser beam <NUM> toward an eye (for example, onto or into a cornea) for plasma mediated (for example, non-UV) photoablation of superficial tissue, or into the stroma of the cornea for intrastromal photodisruption of tissue. In these embodiments, the surgical laser system <NUM> may also include a lens to change the shape (for example, flatten or curve) of the cornea prior to scanning the pulsed laser beam <NUM> toward the eye.

The laser system <NUM> is capable of generating the pulsed laser beam <NUM> with physical characteristics similar to those of the laser beams generated by a laser system disclosed in <CIT>, <CIT>, and <CIT>.

<FIG> illustrates a simplified block diagram of an exemplary controller <NUM> that may be used by the laser system <NUM> according to an embodiment of this invention. Controller <NUM> typically includes at least one processor <NUM> which may communicate with a number of peripheral devices via a bus subsystem <NUM>. These peripheral devices may include a storage subsystem <NUM>, comprising a memory subsystem <NUM> and a file storage subsystem <NUM>, user interface input devices <NUM>, user interface output devices <NUM>, and a network interface subsystem <NUM>. Network interface subsystem <NUM> provides an interface to outside networks <NUM> and/or other devices. Network interface subsystem <NUM> includes one or more interfaces known in the arts, such as LAN, WLAN, Bluetooth, other wire and wireless interfaces, and so on.

User interface input devices <NUM> may include a keyboard, pointing devices such as a mouse, trackball, touch pad, or graphics tablet, a scanner, foot pedals, a joystick, a touch screen incorporated into a display, audio input devices such as voice recognition systems, microphones, and other types of input devices. In general, the term "input device" is intended to include a variety of conventional and proprietary devices and ways to input information into controller <NUM>.

The display subsystem may be a flat-panel device such as a liquid crystal display (LCD), a light emitting diode (LED) display, a touchscreen display, or the like. The display subsystem may also provide a non-visual display such as via audio output devices. In general, the term "output device" is intended to include a variety of conventional and proprietary devices and ways to output information from controller <NUM> to a user.

Storage subsystem <NUM> can store the basic programming and data constructs that provide the functionality of the various embodiments of the present invention. For example, a database and modules implementing the functionality of the methods, as described herein, may be stored in storage subsystem <NUM>. These software modules are generally executed by processor <NUM>. In a distributed environment, the software modules may be stored on a plurality of computer systems and executed by processors of the plurality of computer systems. Storage subsystem <NUM> typically comprises memory subsystem <NUM> and file storage subsystem <NUM>.

Memory subsystem <NUM> typically includes a number of memories including a main random access memory (RAM) <NUM> for storage of instructions and data during program execution and a read only memory (ROM) <NUM> in which fixed instructions are stored. File storage subsystem <NUM> provides persistent (non-volatile) storage for program and data files. File storage subsystem <NUM> may include a hard disk drive along with associated removable media, a Compact Disk (CD) drive, an optical drive, DVD, solid-state memory, and/or other removable media. One or more of the drives may be located at remote locations on other connected computers at other sites coupled to controller <NUM>. The modules implementing the functionality of the present invention may be stored by file storage subsystem <NUM>.

Bus subsystem <NUM> provides a mechanism for letting the various components and subsystems of controller <NUM> communicate with each other as intended. The various subsystems and components of controller <NUM> need not be at the same physical location but may be distributed at various locations within a distributed network. Although bus subsystem <NUM> is shown schematically as a single bus, alternate embodiments of the bus subsystem may utilize multiple busses.

Due to the ever-changing nature of computers and networks, the description of controller <NUM> depicted in <FIG> is intended only as an example for purposes of illustrating only one embodiment of the present invention. Many other configurations of controller <NUM>, having more or fewer components than those depicted in <FIG>, are possible.

As should be understood by those of skill in the art, additional components and subsystems may be included with laser system <NUM>. For example, an imaging device or system may be used to guide the laser beam.

In an embodiment, the laser surgery system <NUM> includes a femtosecond oscillator-based laser operating in the MHz range, for example, <NUM>, for example, from several MHz to tens of MHz. For ophthalmic applications, the XY-scanner <NUM> may utilize a pair of scanning mirrors or other optics (not shown) to angularly deflect and scan the pulsed laser beam <NUM>. For example, scanning mirrors driven by galvanometers may be employed, each scanning the pulsed laser beam <NUM> along one of two orthogonal axes. A focusing objective (not shown), whether one lens or several lenses, images the pulsed laser beam onto a focal plane of the laser surgery system <NUM>. The focal point of the pulsed laser beam <NUM> may thus be scanned in two dimensions (e.g., the X-axis and the Y-axis) within the focal plane of the laser surgery system <NUM>. Scanning along a third dimension, i.e., moving the focal plane along an optical axis (e.g., the Z-axis), may be achieved by moving the focusing objective, or one or more lenses within the focusing objective, along the optical axis. It is noted that in many embodiments, the XY-scanner <NUM> deflects the pulse laser beam <NUM> to form a scan line.

In other embodiments, the beam scanning can be realized with a "fast-scan-slow-sweep" scanning scheme. The scheme consists of two scanning mechanisms: first, a high frequency fast scanner is used to produce a short, fast scan line (e.g., a resonant scanner); second, the fast scan line is slowly swept by much slower X, Y, and Z scan mechanisms.

The use of the terms "a" and "an" and "the" and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The term "connected" is to be construed as partly or wholly contained within, attached to, or joined together, even if there is something intervening. The use of any and all examples, or exemplary language (e.g., "such as") provided herein, is intended merely to better illuminate embodiments of the invention and does not pose a limitation on the scope of the invention unless otherwise claimed.

Claim 1:
An ophthalmic surgical laser system (<NUM>) comprising:
a laser system (<NUM>) configured to generate a pulsed laser beam (<NUM>);
an optical delivery system configured to deliver the pulsed laser beam to a cornea of a patient's eye, including a scanner system (<NUM>, <NUM>) configured to scan a focus spot location of the pulsed laser beam within the cornea;
a controller (<NUM>) configured to control the laser system and the scanner system to:
scan the focus spot location of the pulsed laser beam within the cornea to form a top lenticule surface incision (D-C-C'-D') in the cornea; and
scan the focus spot location of the pulsed laser beam within the cornea to form a bottom lenticule surface incision (B-A-A'-B') in the cornea,
wherein the top and bottom lenticule surface incisions intersect each other to form a volume of corneal tissue (<NUM>) between them, and
wherein the volume of corneal tissue includes a lenticular portion having a circular or oval shape in a top view, and a side tab portion connected to the lenticular portion and that protrudes from a peripheral location of the lenticular portion, wherein the side tab portion has a defined thickness profile in a side cross-sectional view.