Patent Description:
Snare devices have been used to bisect a patient's lens during cataract surgery, in order to facilitate removal of the lens. The device has generally taken the form of an elongated shaft with a wire extending out or near a distal end of the shaft. The wire is in form of a loop that is placed around the lens and then contracted, so that the wire severs the lens and allows the severed lens to be removed from the surrounding lens capsule more easily. One of the problems with the traditional snare devices is that the surgeon cannot see the wire behind the lens, so accurate placement is difficult, and can complicate the surgery. One attempt to make the wire snare more visible is described in <CIT>. In that device, the wire is constructed to be hollow and a light source is in
communication with the lumen of the wire. An aperture in the wire at a point located behind the lens allows the light to escape. The light can be seen through the lens to identify the location of the wire to the surgeon.

One drawback to this configuration is that manufacturing and assembling the wire with the light source is expensive and cumbersome. In addition, the wire must be made larger to accommodate the lumen, and is thus less effective in severing the lens during use. As these devices are generally not re-used, it would be desirable to provide a device for severing a lens that is simple and inexpensive to manufacture as well as effective and reliable during use.

It is therefore an object of the invention to provide an ophthalmic device for severing a lens, in which the wire forming the snare is not required to be hollow. This object is accomplished by an ophthalmic surgical instrument for severing a lens of an eye, comprising an elongated shaft having a distal end portion, and a snare formed by a wire extending along the elongated shaft and having a looped segment disposed adjacent the distal end portion and being configured to move between a contracted configuration and a dilated configuration, in which the looped segment assumes a diameter approximating the diameter and shape of a lens of an eye. When the elongated shaft is inserted through the pupil and the looped segment is placed around the lens, the bottom portion of the looped segment is configured to engage and sever a bottom portion of the lens upon moving toward the contracted configuration. This enables the surgeon to more easily remove the lens during surgery. A light-conducting element extends along at least a portion of a length of the looped segment and a light source is in communication with the light-conducting element, such that light from the light source travels through the light-conducting element and illuminates at least a portion of the length of the looped segment, in order to enable the surgeon to visualize the looped segment after it is placed around the lens.

According to the invention the light-conducting element is adjacent at least a portion of a length of the looped segment, either by providing the light-conducting element in form of a tube that surrounds the wire or by providing the light-conducting element in form of a solid filament that extends adjacent to the wire. The light from the light source travels through the material of the element and exits out a distal end of the element, which can be located at any point along the looped segment but preferably at a place located behind the lens during surgery and preferably at a center of the lens. The point at which the light exits the end of the element forms a bright spot that can be seen through the lens during cataract surgery, so that proper positioning of the snare formed by the looped segment is ensured.

In one embodiment, the light-conducting element is in the form of a solid filament that runs adjacent the wire.

In another embodiment, the light-conducting element is in the form of a tube that surrounds the wire. The tubular structure surrounding the wire creates a greater surface area for light emission as compared to a single strand, thus increasing the visibility of the snare during use.

In a further embodiment, the entire light-conducting element is translucent or transparent, so that the light exits along the length of the element as well, illuminating the entire extent of the looped segment. In this situation, the light-conducting element may extend along an entire length of the looped segment, so that the entire snare is illuminated during surgery. In this embodiment wherein the element tube, the tube is constructed to have a small enough diameter so it can still function to sever the lens during contraction of the wire.

The light-conducting element is preferably made of polyurethane, but any other suitable transparent, translucent or opaque flexible material that scatters light could be used.

In another embodiment, the light conducting element and wire can be covered by an opaque covering so that light from the light source is only visible at an end of the element. In this embodiment, the end of the light-conducting element should be positioned behind the lens during surgery, as this the only area where the light is visible. It is also possible to provide openings along the length of the covering for additional bright spots if desired.

The opaque covering can be made of metal, plastic or any other suitable material. The covering could be woven, braided, coiled, painted or laminated or in any suitable configuration that would allow for movement of the tube and wire during contraction and dilation.

The wire is preferably made of nitinol, which has shape memory capabilities so that an oval shape of the looped segment is maintained throughout use. Other suitable materials could also be used. In one embodiment, the looped portion of the wire has a bend at a bottom of the loop. If the light-conducting element terminates at the bend, the end of the light-conducting element faces toward the shaft, and thus light exiting from the light-conducing element is directed through the lens and back toward the surgeon for maximum visibility.

In a preferred embodiment, the instrument includes a housing connected to the elongated shaft. The housing has an actuator connected to the wire and is configured to move the wire between the contracted and dilated configurations. Preferably, the light source is disposed in the housing and the light-conducting element extends through the elongated shaft into the housing where it is connected to the light source. In another embodiment, the light source is located external to the housing and the light-conducting element extends through the housing and out of the housing to the external light source.

The actuator can take on any suitable form. In one embodiment, the actuator is formed by a sliding element disposed in a slot in the housing. Sliding the sliding element in a direction away from the distal end of the elongated shaft moves the wire into the contracted position, causing the wire to sever the lens, and sliding the sliding element toward the distal end of the elongated shaft moves the wire into the dilated position where it is ready for use.

The light source could be formed by any suitable light source, such as a light-emitting diode (LED). If the light source is disposed in the housing, it is preferably powered by a battery disposed in the housing, so that the instrument is portable and does not require a wired connection to a power source. Alternatively, the light source could be located remote from the surgical instrument, and the tube could extend through the instrument to the light source.

Other objects and features of the present invention will become apparent from the following detailed description considered in connection with the accompanying drawings. It is to be understood, however, that the drawings are designed as an illustration only and not as a definition of the limits of the invention.

In the drawings, wherein similar reference characters denote similar elements throughout the several views:.

Turning to the drawings, <FIG> show an ophthalmic surgical instrument <NUM> that has a housing <NUM>, an elongated shaft in the form of a needle <NUM> having a distal end <NUM>, an opening <NUM> in a side wall thereof, and a snare <NUM> formed by a wire, for severing lenticular tissue. The elongated shaft <NUM> is dimensioned for passage through a corneal incision and has a proximal end portion <NUM> that may be integrally formed with or attached to the housing <NUM> or to a slider cartridge <NUM> shown in <FIG>.

The snare <NUM> of the ophthalmic surgical instrument <NUM> is movable relative to and within the elongated shaft <NUM> via an actuation mechanism formed by slider cartridge <NUM> and slider button <NUM>, which rests in channel <NUM> of slider cartridge <NUM>. Slider cartridge <NUM> is accessible through an opening <NUM> in housing <NUM>. A first end of snare <NUM> is connected to slider button <NUM>, as shown in <FIG>, and the second end of snare <NUM> is fixed within the housing, so that moving slider button <NUM> along channel <NUM> expands and retracts looped segment <NUM> formed by snare <NUM>. Retracting looped segment <NUM> by sliding button <NUM> away from distal end <NUM> allows snare <NUM> to bisect a lens that is disposed within loop <NUM> during surgery.

The snare <NUM> is fabricated from a pliable, metal material, such as, for example, nickel-titanium or any other suitable superelastic material. The snare may be fabricated from any suitable ductile material. Surrounding the snare <NUM> is a light-conducting tube <NUM>, which extends at least partially around the looped segment <NUM>. In the embodiment of <FIG>, tube <NUM> terminates at a distal end <NUM>, which is located at a bottom of the looped segment <NUM>. As shown in <FIG>, tube <NUM> extends around the top portion of looped segment <NUM>, enters the elongated shaft <NUM> with snare <NUM>, extends through slider cartridge <NUM>, and connects to a light source <NUM>, which is disposed in housing <NUM>. Light source <NUM> can be connected to power source <NUM>, such as a battery, also disposed in housing <NUM>, so that the ophthalmic surgical instrument <NUM> is completely portable and wireless.

The light source <NUM> may be a light-emitting diode (LED), a compact fluorescent lamp, an incandescent light bulb, or any other suitable source of light. The light source <NUM> is in communication with the tube <NUM> so that the light from the light source is emitted out of the tube and out of distal end <NUM>. Tube <NUM> is also preferably made of a flexible, translucent material such as polyurethane, so that the light is emitted along the length of the tube <NUM> and is visible along the entire length. In this embodiment, the light would appear as a bright spot at the distal end <NUM> exit as well. In another embodiment, Tube <NUM> is made of an opaque material, or is covered by an opaque coating or covering, so that only the light exiting out of distal end <NUM> is visible. In one embodiment, tube <NUM> can be covered by a metal covering.

In use, the elongated shaft <NUM> is inserted through a corneal incision and a capsulorhexis to position the distal end portion <NUM> around a surface of the lens L. The surgeon is able to use the light emitted from the tube <NUM> to appropriately position the snare <NUM> relative to the lens "L. " With the looped segment <NUM> in the selected position, which is verified using the light transmitted out of the bottom <NUM> of tube <NUM>, the looped segment <NUM> is transitioned from the dilated configuration to the contracted configuration, thereby severing the lens "L.

<FIG> shows an alternative embodiment of the invention, where device <NUM> has an elongated shaft <NUM> with an opening <NUM> through which a snare <NUM> formed by wire extends in a looped segment <NUM>. Snare <NUM> is completely encased in a light-conducting tube <NUM>, which is connected to a light source <NUM>, in the same manner as described above with respect to <FIG>. Tube <NUM> is transparent or translucent, so that the light from light source <NUM> is visible along the entire extent of the snare. Tube <NUM> is thin enough so that snare <NUM> surrounded by tube <NUM> is still able to bisect a lens when snare <NUM> is moved to the retracted position in the manner described above with respect to <FIG> (using the same slider mechanism as described above).

<FIG> shows another alternative embodiment, where light source <NUM> is located outside the housing <NUM> of ophthalmic surgical instrument <NUM>. Snare <NUM> surrounded by tube <NUM> extends entirely through the housing and out to remote light source <NUM>, which can be located on a remote device or by itself. This embodiment allows for the use of a larger, more powerful light source and a larger power supply than may be available to place inside housing <NUM>.

An alternative embodiment of the invention is shown in <FIG> and <FIG>. Here, a light-conducting element in the form of a solid filament <NUM> extends parallel to snare <NUM>, and terminates at a mid-point of looped segment <NUM> of snare <NUM>. A coiled cover <NUM> surrounds the snare <NUM> and filament <NUM> to keep the two components together. Cover <NUM> can be formed of metal wire or any other suitable material, such as a polymer, or any other suitable mixture of materials. In this embodiment, the light from filament <NUM> exits out of end <NUM> and forms a bright spot behind the lens during surgery, in the same manner as explained above with respect to <FIG>. Filament <NUM> is connected to a light source that is disposed in the housing <NUM> or in a location remote from housing <NUM> in the same manner as disclosed with the embodiments of <FIG>.

<FIG> shows a further embodiment of the invention, which is identical to the embodiment of <FIG> and <FIG>, using the instrument of <FIG>, except that in this situation, cover <NUM> is in the form of a woven material, typically a metallic tape or thread, but any other suitable materials could be used as well. It is also envisioned that a cover could be constructed of a solid tube or a molded material that covers both the snare <NUM> and the filament <NUM>.

A further embodiment is shown in <FIG>, here the ophthalmic surgical instrument <NUM> is identical to the instrument shown in <FIG>, except that here, snare <NUM> is bent in two places in opposite directions at a bottom of looped portion <NUM>, in the form of a Z- or S-shape, so that an intermediate section <NUM> between bends <NUM> and <NUM> extends upward toward elongated shaft <NUM>, obliquely to the extent of looped portion <NUM>. Tube <NUM> terminates in the intermediate section <NUM>, so that distal end <NUM> is aimed toward elongated shaft <NUM>. Thus, the bright spot formed by the light exiting tube <NUM> is aimed toward the surgeon during surgery (along arrow A), and is thus more visible, even when viewed through a lens that is substantially opaque with a cataract. The snare of <FIG> could also be used in an embodiment where the light-conducting element is in the form of a solid filament such as shown by filament <NUM> in <FIG>. In either case, the end of the light-conducting element is aimed back toward the elongated shaft <NUM>, so that the brightest part of the apparatus is aimed at the surgeon, thus making the snare more visible behind the lens. The light-conducting element could be covered or coated so that the light is only visible at end <NUM>, such as shown in the embodiment of <FIG>, or can be uncovered so that light is visible along the extent of the light-conducting element, i.e., tube <NUM>.

Claim 1:
An ophthalmic surgical instrument (<NUM>) for severing a lens (L) of an eye, comprising:
an elongated shaft (<NUM>, <NUM>) having a distal end portion (<NUM>);
a wire (<NUM>, <NUM>, <NUM>) extending along the elongated shaft (<NUM>, <NUM>) and having a looped segment (<NUM>, <NUM>) disposed adjacent the distal end portion (<NUM>) and being configured to move between a contracted configuration and a dilated configuration, in which the looped segment (<NUM>, <NUM>) assumes a diameter approximating the diameter and shape of a lens (L) of an eye, the looped segment (<NUM>, <NUM>) having a bottom portion configured to engage and sever a bottom portion of the lens (L) upon moving toward the contracted configuration when the looped segment (<NUM>, <NUM>) is placed around the lens (L),
a light-conducting element (<NUM>, <NUM>, <NUM>) extending along at least a portion of a length of the looped segment (<NUM>, <NUM>), and
a light source (<NUM>, <NUM>, <NUM>) in communication with the light-conducting element (<NUM>, <NUM>, <NUM>), such that light from the light source (<NUM>, <NUM>, <NUM>) travels through the light-conducting element (<NUM>, <NUM>, <NUM>) and illuminates at least a portion of the length of the looped segment (<NUM>, <NUM>),
characterized in that the light-conducting element (<NUM>, <NUM>, <NUM>) is a tube that surrounds the wire (<NUM>, <NUM>, <NUM>).