Patent Description:
Various disorders of the eye may result from diseased/damaged corneal tissue. The diseased/damaged comeal tissue can affect vision by scattering and/or distorting light and causing glare and/or blurred vision. In some cases, proper vision can only be restored by a corneal transplant which replaces the diseased/damaged corneal tissue with healthy tissue from an organ donor. The document <CIT> discloses a dissection device for corneal transplants according to the preamble of claim <NUM>.

The present invention is defined in claim <NUM> and the dependent claims. Systems and methods of the present disclosure employ a manual dissection system to remove diseased/damaged tissue from a cornea according to dimensions that match a corneal implant. For instance, to minimize the removal of the endothelium in a full-thickness transplant, the manual dissection system may remove a volume of diseased/damaged tissue according to a mushroom shape.

According to an example embodiment, a dissection system for corneal transplants includes a housing including a contact side configured to be positioned against a cornea. The housing includes an interior passageway with an opening at the contact side. The dissection system includes a blade assembly disposed in the interior passageway of the housing. The blade assembly includes a first blade and a second blade. The first blade includes a first cutting edge and the second blade includes a second cutting edge. The first blade and the second blade are movable relative to the housing such that the first cutting edge and the second cutting edge extend through the opening of the housing and out of the interior passageway. The first cutting edge is configured to produce a first cut in the cornea disposed at the contact side and the second cutting edge is configured to produce a second cut in the cornea. The first cut and the second cut defines a volume of tissue for removal from the cornea. The dissection system includes one or more manipulators configured to move the first blade and the second blade relative to the housing. The system may further include one or more cutting mechanisms configured to make further cuts transverse to at least one of the first cut or the second cut. The one or more cutting mechanisms may include one or more wires, and the one or more manipulators may be configured to move the wires to make the transverse cuts.

According to another example embodiment, a method operates a dissection system for corneal transplants. The dissection system includes a housing including a contact side configured to be positioned against a cornea, the housing including an interior passageway with an opening at the contact side. The dissection system includes a blade assembly disposed in the interior passageway of the housing. The blade assembly includes a first blade and a second blade, the first blade including a first cutting edge, the second blade including a second cutting edge, and the first blade and the second blade being movable relative to the housing. The dissection system includes one or more manipulators. The method includes positioning the contact side of the housing against a cornea. The method includes operating the one or more manipulators to move the first blade and the second blade relative to the housing such that the first cutting edge and the second cutting edge extend past the opening of the housing and out of the interior passageway. The first cutting edge produces a first cut in the cornea disposed at the contact side and the second cutting edge produces a second cut in the cornea, the first cut and the second cut defining a volume of tissue for removal from the cornea. The method may further include making further cuts, with one or more cutting mechanisms, transverse to at least one of the first cut or the second cut. The one or more cutting mechanisms may include one or more wires, and the method may further comprise operating the one or more manipulators to move the wires to make the transverse cuts.

Various disorders of the eye may result from diseased/damaged corneal tissue. The diseased/damaged corneal tissue can affect vision by scattering and/or distorting light and causing glare and/or blurred vision. In some cases, proper vision can only be restored by a corneal transplant which replaces the diseased/damaged corneal tissue with healthy tissue from an organ donor.

From the outer (anterior) surface of the eye to the inner (posterior) parts, the structure of the cornea includes five layers: (<NUM>) epithelium, (<NUM>) Bownian's layer, (<NUM>) stroma, (<NUM>) Descemet's membrane, and (<NUM>) endothelium. Penetrating keratoplasty (PK) involves a full-thickness transplant where all layers of the cornea from the epithelium to the endothelium are removed and replaced with a corneal implant. In PK, a manual dissection device known as a trephine may be employed to remove the full thickness of existing corneal tissue. The trephine may also be used to cut a donor cornea to provide the corneal implant that dimensionally matches the removed corneal tissue. The corneal implant is then positioned in place of the removed corneal tissue and sutured into place.

Anterior lamellar keratoplasty (ALK) is an alternative treatment that selectively replaces diseased/damaged tissue in an anterior part of the cornea. A type of ALK procedure is deep anterior lamellar keratoplasty (DALK) which removes the epithelium, Bowman's layer, and the stroma but leaves the native Descemet's membrane and endothelium in place. In ALK, the surgeon dissects the cornea and removes the anterior part of the cornea. A dimensionally matching corneal implant from a donor cornea is then positioned in a bed formed by the removal of corneal tissue and sutured into place.

ALK is less invasive than PK and is preferred when the endothelium is healthy. In contrast to the cells of the epithelium and the stroma, the cells of the endothelium cannot regenerate. With ALK, patients retain their own endothelium so the risk of rejection by the immune system may be dramatically reduced.

Although PK involves a full-thickness transplant, certain approaches for PK attempt to minimize the removal of the endothelium. For instance, a patient may have a healthy endothelium, but central corneal scars and full-thickness opacities require a full-thickness transplant. As shown in <FIG>, an example approach for PK removes an anterior portion 2a and a posterior portion 2b of tissue from a cornea <NUM>. The approach illustrated in <FIG> can provide more effective and faster healing. The anterior portion 2a extends from the epithelial surface 2c of the cornea <NUM> to a depth in the stroma 2d to define a first thickness t<NUM> (along the z-axis as shown). The anterior portion 2a has a substantially circular profile along the x-y plane with a first diameter di. For instance, the first thickness ti may be approximately <NUM> to approximately <NUM> and the first diameter d<NUM> may be approximately <NUM>. The posterior portion 2b extends from the anterior portion 2a through the endothelium <NUM>;, to define a second thickness t<NUM>. (along the z-axis). t<NUM> + t<NUM> is the thickness from the epithelial surface 2c through the endothelium. The posterior portion 2b has a substantially circular profile along the x-y plane with a second diameter d<NUM>. For instance, the second thickness t<NUM> may be approximately <NUM> and the second diameter d<NUM> may be approximately <NUM> (or larger). The first diameter d<NUM> of the anterior portion 2a is greater than the second diameter d<NUM> of the posterior portion 2b. The difference between the first diameter d<NUM> and the second diameter d<NUM> may be approximately <NUM> to approximately <NUM>. As such, the portions 2a, b together define a volume of tissue having a mushroom shape. The removal of the posterior portion 2b results in the removal of a smaller section of the endothelium than would be the case if the posterior portion 2b were to have the same diameter d<NUM> as the anterior portion 2a (corresponding to a removal of corneal tissue having a uniform diameter d<NUM>).

As also shown in <FIG>, the removal of the portions 2a, b forms a bed 2f in the cornea <NUM>. The bed 2f also has a mushroom shape. A corneal implant <NUM> is correspondingly shaped to be received in the bed 2f. Using a microkeratome or other conventional dissection device to manually remove the portions 2a, b may not provide die sufficient precision to ensure a dimensional match between the corneal implant <NUM> and the bed 2f. Indeed, the mushroom shape of the corneal implant <NUM> and the bed 2f makes it a greater challenge to achieve a match. Although a femtosecond laser may be employed to cut the portions 2a, b precisely from the cornea <NUM>, practitioners might not be conveniently equipped with a femtosecond laser system to cut the cornea <NUM> according to matching dimensions.

Advantageously, aspects of the present disclosure provide approaches for manually removing corneal tissue with the precision and consistency necessary to match the dimensions of a corneal implant. Such approaches employ devices that are more convenient and cost-effective than a femtosecond laser. With such devices, it is feasible for suppliers to shape a corneal implant with a femtosecond laser or similar high-precision cutting system and for practitioners to remove a volume of tissue manually and form a bed that accurately matches the shape of the corneal implant provided by the supplier.

<FIG> illustrate an example dissection system <NUM> for manually removing corneal tissue. As shown in <FIG>, the dissection system <NUM> includes a housing <NUM>, a blade assembly <NUM>, and a syringe <NUM>. The housing <NUM> has a contact side 100a that can be placed against the cornea <NUM>. The contact side 100a may be contoured to accommodate the general anterior shape of the cornea <NUM>. The housing <NUM> includes a substantially cylindrical outer wall <NUM> that extends upwardly from the contact side 100a (in the positive-z direction). The housing <NUM> includes an interior passageway <NUM> with an opening <NUM> at the contact side 100a.

The housing <NUM> includes one or more vacuum chambers <NUM> that can be coupled to the syringe <NUM> or other negative pressure source via a tube <NUM>. (The vacuum chambers <NUM> are selectively shown in <FIG> with dashed lines. ) The plunger of the syringe <NUM> may be drawn back or otherwise operated to provide a negative pressure in the vacuum chambers <NUM> via the tube <NUM>. One or more vacuum openings <NUM> for the vacuum chambers <NUM> are arranged along the periphery of the opening <NUM> at the contact side 100a. The vacuum openings <NUM> can engage the epithelial surface 2c of the cornea <NUM>. Negative pressure in the vacuum chambers <NUM> generates suction between the epithelial surface 2c and the housing <NUM> at the vacuum openings <NUM>, thereby securely fixing the housing <NUM> to the cornea <NUM>. To decouple the housing <NUM> from the cornea <NUM>, the syringe <NUM> can be operated in an opposite manner to create positive pressure in the vacuum chambers <NUM> and release the suction at the vacuum openings <NUM>.

The housing <NUM> includes positioning elements <NUM> that extend radially outward from the outer wall <NUM>. The positioning elements <NUM> provide sufficient surface area that the practitioner can use to hold and position the housing <NUM>, e.g., between his/her fingers.

The blade assembly <NUM> is disposed in the interior passageway <NUM> of the housing <NUM>. The blade assembly <NUM> includes a manipulator <NUM>, which can be operated to cut the cornea <NUM> with the blade assembly <NUM>. For instance, a threaded coupling may be provided between the housing <NUM> and the blade assembly <NUM>. The manipulator <NUM> may be rotated about the z-axis to cause rotation of the blade assembly <NUM> relative to the housing <NUM>. As it rotates, the blade assembly <NUM> also rides along the thread of the coupling, which thus causes the blade assembly <NUM> to move axially (along the z-axis) relative to the housing <NUM> and the cornea <NUM>. As shown in the top view of <FIG>, the manipulator <NUM> includes a plurality of radially extending rods <NUM> which the practitioner can use to rotate the manipulator <NUM>, e.g., with his/her fingers. The practitioner may simultaneously use the positioning elements <NUM> to hold the housing <NUM> stably in position while rotating the manipulator <NUM>.

Accordingly, the manipulator <NUM> can move the blade assembly <NUM> in the negative-z direction and through the passageway opening <NUM> until the blade assembly <NUM> penetrates the cornea <NUM> positioned against the contact side 100a of the housing <NUM>. The housing <NUM> is securely coupled to the cornea <NUM> so that the blade assembly <NUM> is restricted to predictable and precise movement along the z-axis into the cornea <NUM>.

The blade assembly <NUM> includes an outer blade <NUM> and an inner blade <NUM>. (The outer blade <NUM> and the inner blade <NUM> are selectively shown in <FIG>, <FIG> with dashed lines. ) As shown in the partial view of the dissection system <NUM> in <FIG>, the outer blade <NUM> and the inner blade <NUM> are substantially tubular. The outer blade <NUM> includes a central passageway <NUM> with a substantially circular cutting edge <NUM>. The inner blade <NUM> is disposed in the central passageway <NUM> of the outer blade <NUM> and extends past the cutting edge <NUM> of the outer blade <NUM>. The inner blade <NUM> also includes a central passageway <NUM> with a substantially circular cutting edge <NUM>.

The outer cutting edge <NUM> and the inner cutting edge <NUM> are substantially concentric. Correspondingly, the outer blade <NUM> and the inner blade <NUM> create substantially concentric circular cuts into the cornea <NUM>. When the blade assembly <NUM> penetrates the cornea <NUM>, the circular cut made by the outer cutting edge <NUM> has a larger diameter than the circular cut made by the inner cutting edge <NUM>. For instance, as shown in <FIG>, the outer cutting edge <NUM> may have a diameter that makes a substantially circular outer cut with the first diameter di, which corresponds to the anterior portion 2a removed from the cornea <NUM>. Additionally, the inner cutting edge <NUM> may have a diameter that makes a substantially circular inner cut with the second diameter d<NUM>, which corresponds to the posterior portion 2b removed from the cornea <NUM>.

The manipulator <NUM> moves the outer blade <NUM> and the inner blade <NUM> simultaneously. As shown in the top view <FIG>, the manipulator <NUM> includes an aperture <NUM> that aligns with the central passageway <NUM> of the inner blade <NUM>. As such, the cornea <NUM> can be seen through the aperture <NUM> and the central passageway <NUM>. Cross-hairs <NUM> or other positioning guides may be disposed in the aperture <NUM> and/or the central passageway <NUM> to mark the center of the outer blade <NUM> and the inner blade <NUM>. The practitioner may employ the cross-hairs <NUM> to fix the housing <NUM> to the cornea <NUM> and center the blades <NUM>, <NUM> over a desired location, e.g., the center, of the cornea <NUM>. As such, the location of the cuts made by the outer cutting edge <NUM> and the inner cutting edge <NUM> can be controlled.

As shown in <FIG>, the inner blade <NUM> extends farther downward in the negative-z direction than the outer blade <NUM>. Thus, when the blade assembly <NUM> penetrates the cornea <NUM>, the inner blade <NUM> penetrates the cornea <NUM> to a greater depth than the outer blade <NUM>. The blade assembly <NUM> includes an outer blade depth controller <NUM> to control the penetration depth of the outer blade <NUM> and an inner blade depth controller <NUM> to control the penetration depth of the inner blade <NUM>. For instance, the outer blade depth controller <NUM> and the inner blade depth controller <NUM> may be separately rotated about the z-axis as manual dials to set the respective penetration depths.

As shown in <FIG>, the outer blade depth controller <NUM> may be operated so that the outer blade <NUM> moves past the contact side 100a of the housing <NUM> by a distance that makes an outer cut in the cornea <NUM> with a depth of t<NUM>. This provides the first thickness ti of the anterior portion 2a. Additionally, the inner blade depth controller <NUM> may be operated so that the inner blade <NUM> moves past the contact side 100a of the housing <NUM> by a distance that makes an inner cut in the cornea <NUM> with a depth of t<NUM> + t<NUM>. This provides the second thickness t<NUM> of the posterior portion 2b.

According to an example embodiment, the outer blade depth controller <NUM> can move one or more adjustable stops <NUM> to a position along the interior passageway <NUM> of the housing <NUM>. One or more corresponding stops <NUM> are coupled to the outer blade <NUM>. (The stops <NUM>, <NUM> are selectively illustrated by dashed lines in <FIG>. ) Thus, when the manipulator <NUM> is operated, the outer blade <NUM> can move downwardly in the negative-z direction and penetrate the cornea <NUM> until the stops <NUM> of the outer blade <NUM> reach the stops <NUM> at the set position. The outer blade depth controller <NUM> may provide numerical markers to allow the practitioner to dial a position for the stops <NUM> corresponding to the desired penetration depth t<NUM> for the outer blade <NUM>.

Meanwhile, the inner blade depth controller <NUM> can adjust the distance between the inner cutting edge <NUM> and the outer cutting edge <NUM>. For instance, the inner blade <NUM> may be adjustably coupled to the outer blade <NUM>, e.g., by a threaded coupling, and the inner blade depth controller <NUM> may be operated to adjust the coupling and set the distance. The inner blade depth controller <NUM> may provide numerical markers to allow the practitioner to dial the desired thickness t<NUM> for the posterior portion 2b. This thickness is equivalent to the distance between the cutting edges <NUM>, <NUM>.

Once the distance between the cutting edges <NUM>, <NUM> is set with the inner blade depth controller <NUM>, the manipulator <NUM> may be operated to move the outer blade <NUM> as described above. Correspondingly, the inner blade <NUM> moves with the outer blade <NUM> at the set distance. As illustrated in <FIG>, when the outer blade <NUM> is stopped from further movement by the stops <NUM>, die outer cutting edge <NUM> stops its cut at the desired penetration depth ti and the inner cutting edge <NUM> stops its cut at the set distance t<NUM> from the outer cutting edge <NUM>. Accordingly, the outer blade <NUM> creates an outer cut with the depth and diameter to remove the anterior portion 2a, and the inner blade <NUM> creates an inner cut with the depth and smaller diameter to remove the posterior portion 2b. (The inner cut of the inner blade <NUM> also passes through the anterior portion 2a but does not affect the outer cut of the outer blade <NUM>.

After making the desired outer and inner cuts, the housing <NUM> and the blade assembly <NUM> can be released from die cornea <NUM> by operation of the manipulator <NUM> and the syringe <NUM>. With the precise outer and inner cuts, a separate dissection device or other manual instrument may be employed to remove the anterior portion 2a and the posterior portion 2b. In particular, to remove the anterior portion 2a, an annular cut is made at substantially the penetration depth of t<NUM> for the outer blade, between the outer cut to the inner cut. Additionally, to remove the posterior portion 2b, a circular cut defined by the circumference of the inner cut is made at substantially the penetration depth of t<NUM> + t<NUM> for the inner blade. As described above, the removal of the portions 2a, b produces a bed 2f for receiving the corneal implant <NUM>. With the precision of the cuts by the dissection system <NUM>, the bed 2f provides a dimensional match with the corneal implant <NUM>.

Aspects of the present disclosure are not limited to the embodiment described in <FIG>. For instance, <FIG> illustrates another example dissection system <NUM> including an alternative blade assembly <NUM> with an outer blade <NUM> and an inner blade <NUM>. In contrast to the outer blade <NUM> and the inner blade <NUM> described above, the movement of the inner blade <NUM> is not coupled to the movement of the outer blade <NUM>. As such, the blade assembly <NUM> includes a first manipulator 402a to move the outer blade <NUM> along the z-axis and a second manipulator 402b to move the inner blade <NUM> separately along the z-axis.

The blade assembly <NUM> includes an outer blade depth controller <NUM> that can move one or more adjustable stops <NUM> to a position along the interior passageway <NUM> of the housing <NUM> One or more corresponding stops <NUM> are coupled to the outer blade <NUM>. Similar to the manipulator <NUM>, when the manipulator 402a is operated, the outer blade <NUM> can move downward in the negative-z direction and penetrate the cornea <NUM> until the stops <NUM> of the outer blade <NUM> reach the stops <NUM> at the set position. The outer blade depth controller <NUM> may provide numerical markers to allow the practitioner to dial a position for the stops <NUM> corresponding to the desired penetration depth t<NUM> for the outer blade <NUM>.

The operation of the manipulator 402a, however, does not move die inner blade <NUM>. Thus, the blade assembly <NUM> includes an inner blade depth controller <NUM> that that can move one or more adjustable stops <NUM> to a position along a central passageway <NUM> of the outer blade <NUM> One or more corresponding stops <NUM> are coupled to the inner blade <NUM> When the manipulator 402b is operated, the inner blade <NUM> can move in the negative-z direction and penetrate the cornea <NUM> until the stops <NUM> of the inner blade <NUM> reach the stops <NUM> at the set position. The inner blade depth controller <NUM> may provide numerical markers to allow the practitioner to dial a position for the stops <NUM> corresponding to the desired penetration depth t<NUM> + t<NUM> for the inner blade <NUM>. Accordingly, the practitioner operates each of the manipulators 402a, b separately to make the respective outer and inner cuts.

<FIG> illustrates another example dissection system <NUM> including an alternative blade assembly <NUM> as well as the housing <NUM> and the syringe <NUM>. In contrast to the blade assemblies <NUM>, <NUM> described above, the blade assembly <NUM> includes an outer blade <NUM> and an inner blade <NUM> with constant respective penetration depths. In other words, blade assembly <NUM> does not employ depth controllers that allow the respective penetration depths to be adjusted. For instance, one or more stops <NUM> are fixedly positioned along the interior passageway <NUM> of the housing <NUM>. One or more corresponding stops <NUM> are coupled to the outer blade <NUM>. The blade assembly <NUM> includes a manipulator <NUM> that can be operated to move the outer blade <NUM> in the negative-z direction and penetrate the cornea <NUM> until the stops <NUM> of the outer blade <NUM> reach the stops <NUM> at the set position. The position for the stops <NUM> corresponds to the desired penetration depth t<NUM> for the outer blade <NUM><NUM>.

Additionally, the position of the inner blade <NUM> relative to the outer blade <NUM> cannot be adjusted. The inner blade <NUM> has an inner cutting edge <NUM> that is fixedly positioned at a distance t<NUM> from an outer cutting edge <NUM> of the outer blade <NUM>. As such, when the outer blade <NUM> reaches the desired penetration depth t<NUM>, the inner blade <NUM> reaches a desired penetration depth t<NUM> + t<NUM>. Accordingly, the practitioner operates the manipulator <NUM> to make the same outer and inner cuts.

As described above, a separate dissection device or other manual instrument may be employed to remove the anterior portion 2a and the posterior portion 2b after a blade assembly <NUM>, <NUM>, <NUM> has been manipulated to make cuts in the cornea with the outer blade and the inner blade. In alternative embodiments, however, the blade assembly may be configured to make further cuts to remove the anterior portion 2a and the posterior portion 2b. Such a blade assembly eliminates the need for a separate dissection device or other manual instrument. In particular, to remove the anterior portion 2a, the blade assembly can make a cut (e.g., an annular cut) at the penetration depth of ti, between the outer cut to the inner cut. Additionally, to remove the posterior portion 2b, the blade assembly can make a cut (e.g., a circular cut) defined by the inner cut at the penetration depth of t<NUM> + t<NUM>. The annular and circular cuts are generally transverse to the outer and inner cuts, respectively.

<FIG> illustrate an example dissection system <NUM> employing a blade assembly <NUM>. Like the blade assembly <NUM> described above, the blade assembly <NUM> includes an outer blade <NUM> and an inner blade <NUM> with constant respective penetration depths. The inner blade <NUM> has an inner cutting edge <NUM> that is fixedly positioned at a distance t<NUM> from an outer cutting edge <NUM> of the outer blade <NUM>. As such, when the outer blade <NUM> reaches the desired penetration depth t<NUM>, the inner blade <NUM> reaches a desired penetration depth t<NUM> + t<NUM>.

The dissection system <NUM> includes the housing <NUM> and the syringe <NUM>. As described above, the housing <NUM> can be positioned securely against the cornea <NUM> with the use of a negative pressure provided by the syringe <NUM>. The blade assembly <NUM> is disposed in the interior passageway <NUM> of the housing <NUM>. The housing <NUM> thus positions the blade assembly <NUM> relative to the cornea.

The blade assembly <NUM> includes a manipulator <NUM> that can be rotated about the z-axis to cause the outer blade <NUM> to move relative to the housing <NUM> and the cornea <NUM>. Such movement of the outer blade <NUM> results in corresponding movement of the inner blade <NUM>, which is fixed relative to the outer blade <NUM>. The manipulator <NUM> can be rotated to cause penetration of the outer blade <NUM> to a desired depth t<NUM> and penetration of the inner blade <NUM> to a desired depth t<NUM> + t<NUM>. The manipulator <NUM> includes a plurality of radially extending rods <NUM> which the practitioner can use to rotate the manipulator <NUM>, e.g., with his/her fingers. The practitioner may simultaneously use the positioning elements <NUM> to hold the housing <NUM> stably in position while rotating the manipulator <NUM>.

The blade assembly <NUM> can make an annular cut at the penetration depth t<NUM> between the cuts made by the outer blade <NUM> and the inner blade <NUM>. Additionally, at the penetration depth t<NUM> + t<NUM>,the blade assembly <NUM> can make a circular cut with a circumference defined by the inner blade <NUM>. Together, the annular cut and the circular cut allow the anterior portion 2a and the posterior portion 2b to be removed.

As shown in <FIG>, the blade assembly <NUM> includes wires <NUM> (or similar cutting structures) that extend between the outer blade <NUM> and the inner blade <NUM> within the central passageway <NUM> of the outer blade <NUM>. The wires <NUM> are aligned with the outer cutting edge <NUM> of the outer blade <NUM> (i.e., generally, at the same position on the z-axis as the outer cutting edge <NUM>). Additionally, the blade assembly <NUM> includes a wire <NUM> (or similar cutting structure) that extends across the central passageway <NUM> of the inner blade <NUM>. The wire <NUM> is aligned with the inner cutting edge <NUM> of the inner blade <NUM> (i.e., generally, at the same position on the z-axis as the inner cutting edge <NUM>).

When the outer cutting edge <NUM> of the outer blade <NUM> penetrates the cornea <NUM> to the desired depth t<NUM>, the wires <NUM> also penetrate the cornea <NUM> to the desired depth t<NUM>. Meanwhile, when the inner cutting edge <NUM> of the inner blade <NUM> correspondingly penetrates the cornea <NUM> to the desired depth t<NUM> + t<NUM>, the wire <NUM> also penetrates the cornea to the desired depth t<NUM> + t<NUM>. The wires <NUM>, <NUM> have sufficient tension and sharpness to cut through the cornea <NUM> and do not generate significant resistance against the movement of the outer blade <NUM> and the inner blade <NUM>. Although <FIG> illustrate two wires <NUM> and one wire <NUM> as an example, embodiments may employ different numbers of wires <NUM> and/or wires <NUM>. The wires <NUM>, <NUM> can penetrate the cornea <NUM>, because the outer blade <NUM> and the inner blade <NUM> do not rotate relative to the housing <NUM> and the cornea <NUM> when penetrating the cornea <NUM>.

<FIG> illustrates an example configuration for coupling the manipulator <NUM> to the outer blade <NUM> and the inner blade <NUM>. The example configuration allows the manipulator <NUM> to be operated so that the outer blade <NUM> and the inner blade <NUM> move axially along the z-axis to penetrate the cornea <NUM> without rotating about the z-axis.

As shown in <FIG>, the manipulator <NUM> is coupled to the housing <NUM>. The manipulator <NUM> can rotate about the z-axis relative to the housing <NUM>, but cannot move according to other degrees of freedom relative to the housing <NUM>. For instance, the manipulator <NUM> may include engagement structures <NUM> that can snap into an annular track <NUM> running along a surface (e.g., top surface) of the housing <NUM>; the engagement structures <NUM> can move within the annular track <NUM> to allow rotation of the manipulator <NUM>.

The manipulator <NUM> includes a central passageway <NUM>. The outer blade <NUM> is disposed within the central passageway <NUM>. The outer blade <NUM> includes an outer surface <NUM> that faces an inner surface <NUM> of the manipulator <NUM> within the central passageway <NUM>. The manipulator <NUM> includes a thread <NUM> that spirals along the inner surface <NUM>. The outer blade <NUM> includes tabs <NUM> that are biased to extend radially outward from the outer surface <NUM> and engage the thread <NUM>. When the manipulator <NUM> is rotated in a first direction about the z-axis, the thread <NUM> applies a force against the tabs <NUM> in the negative-z direction. This force causes the outer blade <NUM>, as well as the inner blade <NUM> fixed to the outer blade <NUM>, to move in the negative-z direction and penetrate the cornea <NUM>. The movement of the outer blade <NUM> and the inner blade <NUM> does not involve rotation about the z-axis relative to the housing <NUM> and the cornea <NUM>. In some cases, the housing <NUM> may include one or more guide structures to engage the outer blade <NUM> and prevent such rotation while allowing movement along the z-axis. Rotation of the manipulator <NUM> in the first direction stops when the outer blade <NUM> and the inner blade <NUM> reach their respective desired penetration depths t<NUM> and t<NUM> + t<NUM>, respectively.

Once the outer blade <NUM> and the inner blade <NUM> reach the desired penetration depths, the manipulator <NUM> can be further operated to make additional cuts (e.g., transverse cuts) to allow the anterior portion 2a and the posterior portion 2b to be removed. In particular, the manipulator <NUM> can be rotated in a second direction about the z-axis to cause the wires <NUM>, <NUM> to rotate about the z-axis. This second direction is opposite from the first direction in which the manipulator <NUM> is rotated to move the outer blade <NUM> and the inner blade <NUM> in the negative-z direction. Rotation of the wires <NUM> makes an annular cut at the penetration depth t<NUM>, between the outer cut to the inner cut. Meanwhile, rotation of the wire <NUM> makes a circular cut at the penetration depth of t<NUM> + t<NUM>.

As shown in <FIG>, when the manipulator <NUM> is rotated in the second direction about the z-axis, the outer blade <NUM> and the inner blade <NUM> do not move in the positive-z direction. Although the thread <NUM> may apply a force against the tabs <NUM> in the positive-z direction, the tabs <NUM> are shaped (e.g., with an angled surface) so that such force also pushes the tabs <NUM> radially inward. The force overcomes the radially outward bias of the tabs <NUM>, causing the tabs to move radially inward. This inward movement of the tabs <NUM> prevents the force in the positive-z direction from pushing the outer blade <NUM> and the inner blade <NUM> in the positive-z direction.

The manipulator <NUM> includes tabs <NUM> that engage the tabs <NUM> of the outer blade <NUM> as the manipulator is rotated in the second direction. The engagement between the tabs <NUM>, <NUM> causes the outer blade <NUM> as well as the inner blade <NUM> to rotate in the second direction with the manipulator <NUM>. The wires <NUM>, <NUM> rotate correspondingly with the outer blade <NUM> and inner blade <NUM>. Because the thread <NUM> does not move the outer blade <NUM> and inner blade <NUM> along the z-axis, the wires <NUM>, <NUM> rotate on the x-y planes at the depths t<NUM> and t<NUM> + t<NUM>, respectively, to produce the desired cuts.

Once the cuts with the wires <NUM>, <NUM> are completed, the anterior portion 2a and the posterior portion 2b can be removed from the cornea <NUM>. In some cases, withdrawal of the dissection system <NUM> from the cornea <NUM> also removes the dissected tissue.

The outer blade <NUM> and the inner blade <NUM> can be reset relative to the manipulator <NUM> and the housing <NUM> for a subsequent dissection procedure. As shown in <FIG>, each tab <NUM> is disposed on one end of a biasing structure <NUM> positioned within the outer blade <NUM>. The biasing structure <NUM> pushes the tabs <NUM> radially outward through the outer surface <NUM> of the outer blade <NUM>. A button <NUM> is disposed near the other end of the biasing structure <NUM> and also extends radially outward through the outer surface <NUM>. When the button <NUM> is pushed radially inward, resulting movement of the biasing structure <NUM> causes the tab <NUM> to also move radially inward and to disengage the track <NUM> of the manipulator <NUM>. Accordingly, the buttons <NUM> can be squeezed together with fingers to allow the outer blade <NUM>, as well as the inner blade <NUM>, to be moved in the positive-z direction, back to a starting position for the subsequent dissection procedure.

<FIG> illustrates an alternative configuration for coupling the manipulator <NUM> to the outer blade <NUM> and the inner blade <NUM>. Similar to the configuration of <FIG>, the manipulator <NUM> is coupled to the housing <NUM> (not shown). The manipulator <NUM> can rotate about the z-axis relative to the housing <NUM>, but cannot move according to other degrees of freedom relative to the housing <NUM>. In addition, the manipulator <NUM> includes the central passageway <NUM>. The outer blade <NUM> is disposed within the central passageway <NUM>. The outer surface <NUM> of the outer blade <NUM> faces the inner surface <NUM> of the manipulator <NUM>.

As shown in <FIG>, the manipulator <NUM> includes the thread <NUM> which spirals along the inner surface <NUM>. The outer blade <NUM> includes tabs <NUM> that are biased to extend radially outward from the outer surface <NUM> and engage the threads <NUM>. When the manipulator <NUM> is rotated in a first direction about the z-axis, the thread <NUM> applies a force against the tabs <NUM> in the negative-z direction. This force causes the outer blade <NUM>, as well as the inner blade <NUM> fixed to the outer blade <NUM>, to move in the negative-z direction and penetrate the cornea <NUM>. The movement of the outer blade <NUM> and the inner blade <NUM> does not involve rotation about the z-axis relative to the housing <NUM> and the cornea <NUM>. In some cases, the housing <NUM> may include one or more guide structures to engage the outer blade <NUM> and prevent such rotation while allowing movement along the z-axis.

Unlike the configuration of <FIG>, the tabs <NUM> continue to move along the thread <NUM> until they enter a groove <NUM> at the end of the thread <NUM>. At this point, the outer blade <NUM> and the inner blade <NUM> have reached their desired penetration depths t<NUM> and t<NUM> + t<NUM>, respectively. With the tabs <NUM> positioned in the groove <NUM>, the thread <NUM> can no longer apply a force to the tabs <NUM> and the manipulator <NUM> can be further rotated in the same first direction about the z-axis to make additional cuts to allow the anterior portion 2a and the posterior portion 2b to be removed.

The manipulator <NUM> includes tabs <NUM> that engage the tabs <NUM> of the outer blade <NUM> as the manipulator continues to rotate in the first direction. The engagement between the tabs <NUM>, <NUM> causes the outer blade <NUM> as well as the inner blade <NUM> to rotate in the first direction with the manipulator <NUM>. The wires <NUM>, <NUM> rotate correspondingly with the outer blade <NUM> and inner blade <NUM>. Because the thread <NUM> does not move the outer blade <NUM> and inner blade <NUM> along the z-axis, the wires <NUM>, <NUM> rotate on the x-y planes at the depths t<NUM> and t<NUM> + t<NUM>, respectively, to produce the desired cuts. As described above, rotation of the wires <NUM> makes an annular cut at the penetration depth t<NUM>, between the outer cut to the inner cut. Meanwhile, rotation of the wire <NUM> makes a circular cut at the penetration depth of t<NUM> + t2.

The outer blade <NUM> and the inner blade <NUM> can be reset relative to the manipulator <NUM> and the housing <NUM> for a subsequent dissection procedure. As shown in <FIG>, each tab <NUM> is disposed on one end of the biasing structure <NUM> positioned within the outer blade <NUM>. The biasing structure <NUM> pushes the tabs <NUM> radially outward through the outer surface <NUM> of the outer blade <NUM>. A button <NUM> is disposed near the other end of the biasing structure <NUM> and also extends radially outward through the outer surface <NUM>. When the button <NUM> is pushed radially inward, resulting movement of the biasing structure <NUM> causes the tab <NUM> to also move radially inward and allows the tab <NUM> to disengage the track <NUM> of the manipulator <NUM>. Accordingly, the buttons <NUM> can be squeezed together with fingers to allow the outer blade <NUM>, as well as the inner blade <NUM>, to be moved in the positive-z direction, back to a starting position for the subsequent dissection procedure.

As shown in <FIG>, the wires <NUM>, <NUM> in the example dissection system <NUM> have sufficient tension and sharpness to cut through die cornea <NUM> as the outer blade <NUM> and the inner blade <NUM> penetrate the cornea <NUM>. Operation of the manipulator <NUM> to rotate the wires <NUM>, <NUM> can also increase the tension in the wires <NUM>, <NUM>. Alternative embodiments, however, may provide additional support for the movement of the wires <NUM>, <NUM> in the negative-z direction. For instance, <FIG> illustrates the outer blade <NUM> and the inner blade <NUM>, as well as the wires <NUM>, <NUM> described above. <FIG> shows a support structure <NUM> extending between the outer blade <NUM> and the inner blade <NUM> and to the cutting edge <NUM> of the outer blade <NUM>. One of the wires <NUM> is disposed at the end of the support structure <NUM> and aligned with the cutting edge <NUM>. The end of the support structure <NUM> may be recessed or otherwise shaped to engage the wire <NUM> further. An additional support structure <NUM> (not shown) may be implemented with the other wire <NUM>. Meanwhile, <FIG> shows a support structure <NUM> extending to the cutting edge <NUM> within the central passageway <NUM> of the inner blade <NUM>. The wire <NUM> is disposed at the end of the support structure <NUM> and aligned with the cutting edge <NUM>. The end of the support structure <NUM> may be recessed or otherwise shaped to engage the wire <NUM> further. The support structures <NUM>, <NUM> move with the outer blade <NUM> and the inner blade <NUM> as they penetrate the cornea <NUM>. Advantageously, the support structures <NUM>, <NUM> help the wires <NUM>, <NUM> to move through the cornea <NUM>. When the outer blade <NUM> and the inner blade <NUM> reach their respective desired penetration depths, the manipulator <NUM> may be operated as described above to make the additional cuts with the wires <NUM>, <NUM>. In this case, the wires <NUM>, <NUM> disengage from the respective support structures <NUM>, <NUM> to rotate with the manipulator <NUM>.

As shown in <FIG>, the support structures <NUM>, <NUM> may have a wedge-like or blade-like shapes extending substantially along the length of the outer blade <NUM> and the inner blade <NUM>, respectively. In other embodiments, however, the support structures <NUM>, <NUM> may have alternative shapes. For instance, the support structures <NUM>, <NUM> may be shorter cross-bars that extend across and above the wires <NUM>, <NUM> to provide support.

<FIG> illustrate an alternative approach for supporting for the movement of the wires in the negative-z direction. For instance, <FIG> illustrates a support structure <NUM> for a wire <NUM>. (In contrast to the examples above, a single wire <NUM> is employed here. ) The end 683a of the support structure <NUM> provides a leading edge as the outer blade <NUM> and the inner blade <NUM> penetrate the cornea <NUM>. In <FIG>, the support structure <NUM> includes a recess 683b that receives the wire <NUM> above the end 683a of the support structure <NUM>. In contrast, the wire <NUM> in FIGS. 6A-C is positioned below the support structure <NUM> and provides the leading edge. Advantageously, the end 683a may be sharper than the wire <NUM> and can cut through the cornea <NUM> more easily while the wire <NUM> remains in the recess 683b.

When the outer blade <NUM> and the inner blade <NUM> reach the respective desired penetration depths, the manipulator <NUM> may be operated to disengage the wire <NUM> from the recess 683b in the support structure <NUM> and to rotate the wire <NUM> about the z-axis to produce the cuts to help remove the anterior portion 2a. Although the wire <NUM> is received in the recess disposed above the end 683a of the support structure <NUM>, the support structure <NUM> delivers the wire <NUM> to a depth where the wire <NUM> can provide an effective cut near the penetration depth t<NUM> (e.g., within approximately <NUM>).

To make the circular cut at or near the penetration depth ti + t<NUM>, a wire <NUM>' as shown in the views of <FIG> may be employed. The support structure <NUM> for the wire <NUM>' may be configured to receive the wire <NUM>' in a recess 685b in a manner similar to the support structure <NUM>. In contrast to the support structure <NUM> and the wire <NUM> which extends across the entire diameter of the inner blade <NUM>, the wire <NUM>' extends across the radius of the inner blade <NUM>. The wire <NUM>' extends from a center support <NUM> to an inner wall of the inner blade <NUM>. The wire <NUM>' can rotate about the center support <NUM> to make the desired circular cut.

In <FIG>, die rotation of the wires <NUM>, <NUM>' starts from one side of the support structures <NUM>, <NUM> (i.e., out of the recesses 683b, 685b) and ends on the other side of the support structures <NUM>, <NUM>, respectively. As such, the wires <NUM>, <NUM>' are blocked by the support structures <NUM>, <NUM> from making complete annular and circular cuts, respectively. The cuts by the wires <NUM>, <NUM>', however, are sufficient to allow removal of the anterior portion 2a and posterior portion 2b, respectively.

Although the inner and outer blades of the example embodiments above may have substantially circular profiles, it is understood that the other embodiments may employ other profiles to make cuts of different shapes, e.g., elliptical cuts. Additionally, it is understood that the blade assemblies in other embodiments may be configured to make non-concentric inner and outer cuts. Furthermore, it is understood that the blade assemblies in other embodiments may include more than two blades.

Although the inner cuts made by the inner blade in the example implementations above may have penetration depths that extend through the endothelium, it is understood that other implementations may employ penetration depths that do not extend completely to the endothelium. Furthermore, although the blade assemblies of the example embodiments above may remove a volume of corneal tissue having a mushroom shape, it is contemplated that blade assemblies in other embodiments may be configured to make cuts that allow corneal tissue to be removed according to other shapes.

Claim 1:
A dissection device (<NUM>) for corneal transplants, comprising:
a housing (<NUM>) including a contact side (<NUM> a) configured to be positioned against a cornea, the housing (<NUM>) including an interior passageway (<NUM>) with an opening (<NUM>) at the contact side (<NUM> a);
a blade assembly (<NUM>) disposed in the interior passageway (<NUM>) of the housing (<NUM>), the blade assembly (<NUM>) including a first blade (<NUM>) and a second blade (<NUM>), the first blade (<NUM>) including a first cutting edge (<NUM>), the second blade (<NUM>) including a second cutting edge (<NUM>), the first blade (<NUM>) and the second blade (<NUM>) being movable relative to the housing (<NUM>) such that the first cutting edge (<NUM>) and the second cutting edge (<NUM>) are configured to extend past the opening (<NUM>) of the housing (<NUM>) and out of the interior passageway (<NUM>), wherein the first cutting edge (<NUM>) is configured to produce a first cut in the cornea disposed at the contact side (<NUM> a) and the second cutting edge (<NUM>) is configured to produce a second cut in the cornea, the first cut and the second cut defining a volume of tissue for removal from the cornea; and
one or more manipulators (<NUM>) configured to move the first blade (<NUM>) and the second blade (<NUM>) relative to the housing (<NUM>),
characterized by:
the first cutting edge (<NUM>) and the second cutting edge (<NUM>) are substantially circular;
the substantially circular first cutting edge (<NUM>) is concentric with the substantially circular second cutting edge (<NUM>), and the substantially circular first cutting edge (<NUM>) has a first diameter that is larger than a second diameter of the second cutting edge (<NUM>); and
the second cutting edge (<NUM>) is configured to extend past the opening (<NUM>) of the housing (<NUM>) by a larger distance than the first cutting edge (<NUM>), the second cut extending to a second depth into the cornea that is larger than a first depth of the first cut into the cornea based on the larger distance.