Patent Description:
In ophthalmology, eye surgery, or ophthalmic surgery, is performed on the eye and accessory visual structures. More specifically, vitreoretinal surgery encompasses various delicate procedures involving internal portions of the eye, such as the vitreous humor and the retina. Different vitreoretinal surgical procedures are used, sometimes with lasers, to improve visual sensory performance in the treatment of many eye diseases, including epimacular membranes, diabetic retinopathy, vitreous hemorrhage, macular hole, detached retina, and complications of cataract surgery, among others.

During vitreoretinal surgery, an ophthalmologist typically uses a surgical microscope to view the fundus through the cornea, while surgical instruments that penetrate the sclera may be introduced to perform any of a variety of different procedures. The surgical microscope provides imaging and optionally illumination of the fundus during vitreoretinal surgery. The patient typically lies supine under the surgical microscope during vitreoretinal surgery and a speculum is used to keep the eye exposed. Depending on a type of optical system used, the ophthalmologist has a given field of view of the fundus, which may vary from a narrow field of view to a wide field of view that can extend to peripheral regions of the fundus. For many types of vitreoretinal surgery using the surgical microscope, the surgeon may desire to have a very wide field of view of the fundus that extends beyond the equator and even out to the ora serrata. The optical system to provide the view of the fundus to the surgeon during vitreoretinal surgery may include a special ocular lens, of which three types are typically used: a direct (plano, flat, or magnifying) contact lens, an indirect noncontact lens, or an indirect contact lens.

A contact lens is in physical contact with the cornea and therefore has a concave surface to match the convex surface of the cornea. Typically a small amount of gel or fluid resides between the cornea and the contact lens to prevent unwanted extraneous interfacial reflections and to protect the cornea from dehydration. Because of the thermal mass of many contact lenses, such as those incorporating multiple internal objectives, high water vapor content of the air near the eye, and the ambient conditions in operating rooms, contact lenses may be subject to fogging during surgery, which is undesirable because the surgeon's view of the fundus is obstructed. Documents <CIT> and <CIT> have been cited as relating to the state of the art. Reference is made to <CIT> described therein as relating to an imaging apparatus for an endoscope, and more particularly to an imaging apparatus having a dew condensation prevention function. This document provides an endoscope imaging apparatus having a cover member is provided between a solid-state imaging device and an objective optical system, wherein a heating member is disposed in the vicinity of the cover member.

The scope is in accordance with the appended claims.

The claims are directed to a contact lens assembly for ophthalmic surgery, the contact lens assembly arranged for fogging prevention.

The specification also includes description of associated methods and related arrangement, outside the scope of the present claims but provided to assist in understanding the invention and as background.

In another aspect, a disclosed contact lens assembly as defined in claim <NUM> is configured for use in ophthalmic surgery. The contact lens may include an anti-fogging device coupled to the contact lens. In the contact lens, the antifogging device delivers thermal energy to the contact lens while the contact lens is in use during ophthalmic surgery to view an interior portion of an eye of a patient using a surgical microscope.

The anti-fogging device may include an electrical heating element disposed on a surface of the contact lens to generate the thermal energy. In the contact lens, the electrical heating element may include a transparent conductor. In any of the disclosed embodiments of the contact lens, the anti-fogging device may include an electrical heating element disposed on a ring surrounding the contact lens.

The anti-fogging device further includes a handle for supporting the contact lens on the eye during surgery.

The thermal energy may be delivered via the handle.

Electrical energy to generate the thermal energy is delivered via lead lines attached to the handle.

For a more complete understanding of the present invention and its features and advantages, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which:.

In the following description, details are set forth by way of example to facilitate discussion of the disclosed subject matter. It should be apparent to a person of ordinary skill in the field, however, that the disclosed embodiments are exemplary and not exhaustive of all possible embodiments.

As noted above, contact lenses, often comprised of multiple objectives, may have a relatively high thermal mass and may experience fogging during ophthalmic surgery. Typically in an operating room where ophthalmic surgery is being performed, the ambient conditions may include high humidity and cooling air from ventilation systems may be present. Thus, the contact lens may become cold, while local humidity near the surgical procedure, particularly around the eye, may be increased, which may result in condensation forming on the surface of the contact lens. Because such fogging may be unpredictable or spontaneous, the resulting loss of view of the fundus for the surgeon may impede the normal course of the surgical procedure being performed, which is undesirable.

As will be described in further detail, the inventors of the present disclosure have developed methods and systems for fogging prevention for surgical contact lenses. The methods and systems for fogging prevention disclosed herein may include an anti-fogging device that delivers thermal energy to the contact lens during ophthalmic surgery. The methods and systems for fogging prevention disclosed herein may deliver thermal energy to heat the contact lens above an ambient dew point to prevent condensation (fogging) of the contact lens during surgery. The methods and systems for fogging prevention disclosed herein may enhance safety of ophthalmic surgery by preventing the view of the surgeon from being obscured by fogging of the contact lens during surgical procedures.

Referring now to the drawings, <FIG> illustrates a depiction of an embodiment of a ophthalmic surgery <NUM> using a surgical microscope <NUM> and contact lens <NUM>. In <FIG>, the use of contact lens <NUM> with a patient and a surgeon is depicted. Although <FIG> is shown with surgical microscope <NUM> above the patient, it is noted that different orientations of the patient with respect to surgical microscope <NUM> may be practiced in different embodiments. In particular embodiments, contact lens <NUM> may be an indirect contact lens.

The patient has an eye exposed using a speculum <NUM> that is in contact with contact lens <NUM>, while the surgeon is viewing the fundus of the patient's eye using surgical microscope <NUM>. Furthermore, a lens handle <NUM> is attached to contact lens <NUM> using a mounting clip <NUM> and is shown held in place by a surgical technician (or other personnel) to maintain alignment of a first optical axis <NUM> of contact lens <NUM> with a second optical axis <NUM> of surgical microscope <NUM>, thereby enabling useful imaging for the surgeon to be maintained during surgery. Mounting clip <NUM> may be a single-use item to maintain sterility and may be disposable. It is noted that different means for supporting contact lens <NUM> may be used in different embodiments.

The objective used with surgical microscope <NUM> may have a focal length of about <NUM> to <NUM> that may focuses on a focal plane of contact lens <NUM>. As long as contact lens <NUM> remains free from condensation (fogging), the surgeon may be provided with field of view of the fundus of the eye via surgical microscope <NUM> and may safely proceed with any of a variety of ophthalmic surgical procedures (not shown).

However, when contact lens <NUM> is fogged, typically at a top exterior surface of contact lens <NUM> exposed to ambient conditions, the optical path of surgical microscope <NUM> may become obstructed and the surgeon can no longer view the fundus of the eye. Such fogging may occur relatively quickly and without warning during surgery and may even occur at moments when the surgeon is applying the utmost care and skill to perform minute operations in the fundus, such as membrane peeling and manipulation, drainage of subretinal fluid, endolaser application, among others. Therefore, fogging of contact lens <NUM> may result in unnecessary delays and interruptions and may represent a potentially serious risk during ophthalmic surgery. As noted above, the ambient conditions in the operating room may be conducive to fogging of contact lens <NUM>, such as humidity and low temperatures, which may vary locally at the location of contact lens <NUM> during surgery, resulting in unpredictable fogging behavior of contact lens <NUM>.

As shown in ophthalmic surgery <NUM>, contact lens <NUM> is equipped with an anti-fogging device that delivers thermal energy to contact lens <NUM>. The anti-fogging device may be activated to maintain visibility through contact lens <NUM> when ophthalmic surgery <NUM> is performed.

In the embodiment depicted in <FIG>, the anti-fogging device comprises an air duct <NUM> that may be coupled to, or integrated with, lens handle <NUM> that is attached via mounting clip <NUM> to contact lens <NUM>. For example, lens handle <NUM> may be formed using stainless steel or polyether ether ketone (PEEK), which are materials that may be subject to autoclaving for disinfection. Specifically, air duct <NUM> may terminate with an air nozzle <NUM> that is directed to the surface of contact lens <NUM> from an edge of contact lens <NUM>. Air duct <NUM> may direct warmed air over the flange edge of contact lens <NUM> to reach the optical surface of contact lens <NUM>. An air supply system (not visible in <FIG>) may provide pressurized air at a desired temperature and a desired humidity to air nozzle <NUM> via fluid coupling through air duct <NUM>. In this manner, at least the surface of contact lens <NUM> may be kept above the local ambient dew point and condensation (fogging) may be prevented. It is noted that the temperature, humidity, pressure, flow rate, or a combination of such parameters of the pressurized air flowing through air nozzle <NUM> may be regulated to a desired value. Air nozzle <NUM> or air duct <NUM> or both may be single-use items to maintain sterility and may be disposable. Because the dew point may be relatively low, a relatively small increase in temperature relative to the ambient temperature in the operating room of ophthalmic surgery <NUM> may suffice for the pressurized air to be anti-fogging at the surface of contact lens <NUM>.

In addition to the embodiment of the anti-fogging device depicted in <FIG>, additional embodiments of the anti-fogging device may be implemented, as described below in the example implementations shown in <FIG>.

Referring now to <FIG>, selected elements of an embodiment of an anti-fogging device <NUM> for contact lens <NUM> are shown. In <FIG>, anti-fogging device <NUM> comprises an electrical heating element <NUM> shown formed as a circular ring at a peripheral portion of the surface of contact lens <NUM>. In other embodiments, electrical heating element <NUM> may be placed at other positions in contact with contact lens <NUM>, such as attached to a housing of contact lens <NUM>, attached to a ring-shaped flange of contact lens <NUM>, or attached to mounting clip <NUM> of lens handle <NUM>. Electrical heating element <NUM> is coupled at both ends to lead lines <NUM>, which may be insulated wires that are attached to an external power source (not shown) via connector <NUM>. In various embodiments, lead lines <NUM> or connector <NUM> or both may be coupled to or integrated with lens handle <NUM>, such that lead lines <NUM> are held in place using lens handle <NUM>.

Connector <NUM> may be an electrical plug or an electrical socket with two poles for each respective lead line <NUM>. When connector <NUM> is connected to the external power source, an electrical circuit including electrical heating element <NUM> is closed and current may flow through electrical heating element <NUM>. Various different types of external power sources may be used with anti-fogging device <NUM>, including direct current (DC) or alternating current (AC) sources. In some embodiments, the external power source is included in surgical equipment present in the operating room such that connector <NUM> is plugged in to the surgical equipment.

As a result of the inherent resistivity of a material used to form electrical heating element <NUM>, electrical heating element <NUM> will increase in temperature when the current flows through electrical heating element <NUM>, thereby delivering a certain amount of thermal energy to the surface of contact lens <NUM> to prevent condensation (fogging) from occurring at the surface.

It is noted that electrical heating element <NUM> may be formed using various materials. For example, a metallic material, such as a nickel-chrome (Ni-Cr) alloy, an iron-chrome-aluminum (FeCrAl) alloy, or a copper-nickel (Cu-Ni) alloy, among others, may comprise at least a portion of electrical heating element <NUM>. In some embodiments, a transparent conductor, such as indium tin oxide (ITO), may comprise at least a portion of electrical heating element <NUM> in order to minimize any optical effects of introducing anti-fogging device <NUM> to contact lens <NUM>. In different embodiments, electrical heating element <NUM> may comprise a ceramic material, such as a positive thermal coefficient (PTC) of resistance ceramic, including but not limited to barium titanate, lead titanate, and composites thereof. In some embodiments, a conductive polymer, such as a PTC rubber material, among others, may be used for electrical heating element <NUM>. It is further noted that while a circular form is shown for electrical heating element <NUM> in <FIG>, other forms or shapes may be used for electrical heating element <NUM>.

Similar to the anti-fogging device shown in <FIG>, it will be understood that the power output of anti-fogging device <NUM> may be regulated to deliver a certain amount of power, to deliver a certain amount of heat, or to maintain a certain desired temperature, or a desired temperature difference, such as with the ambient air, at contact lens <NUM>. Accordingly, a temperature sensor may additionally be included with contact lens <NUM> and may be used for regulation purposes in particular embodiments. In various embodiments, a fixed amount of electrical current is continuously provided to electrical heating element <NUM> to provide enough thermal energy to maintain contact lens <NUM> at a temperature above the ambient dew point. Because the amount of thermal energy to maintain contact lens <NUM> at a temperature above the ambient dew point may be relatively, small, the electrical current flowing through electrical heating element <NUM> may be relatively small, such as a few milliamperes, depending on the dimensions and resistivity of electrical heating element <NUM>.

Referring now to <FIG>, selected elements of an arrangement outside the scope of the present claims, of an anti-fogging device <NUM> for contact lens <NUM> are shown. In <FIG>, anti-fogging device <NUM> comprises a fluid duct <NUM> in thermodynamic contact with contact lens <NUM>. In particular arrangements fluid duct <NUM> may be formed comprising a thermally conductive material, such a metal tube. Anti-fogging device <NUM> may comprise a coil formed with fluid duct <NUM> that is shaped to mate with contact lens <NUM>. In various arrangements, fluid duct <NUM> may be coupled to or integrated with lens handle <NUM>, such that fluid duct <NUM> is held in place using lens handle <NUM>.

As shown, a heat transfer fluid may enter fluid duct <NUM> from a manifold <NUM> in direction <NUM> and may exit fluid duct <NUM> in direction <NUM> to manifold <NUM>. Manifold <NUM> may further include a reservoir, a heating system, and a pump system (not shown) to enable circulation of the heat transfer fluid at a desired temperature through fluid duct <NUM> in order to warm contact lens <NUM> for anti-fogging purposes. In given embodiments, the heat transfer fluid may be an aqueous solution, such as an aqueous saline solution or a sterile water solution. Similar to the anti-fogging devices shown in <FIG> and <FIG>, it will be understood that the temperature of the heat transfer fluid entering fluid duct <NUM> of antifogging device <NUM> may be regulated to deliver a certain amount of heat, or to maintain a certain desired temperature, or a desired temperature difference, such as with the ambient air, at contact lens <NUM>. Accordingly, the temperature of the heat transfer fluid entering and exiting fluid duct <NUM> may be monitored and used for regulation purposes. In various arrangements, a fixed amount of thermal energy is continuously provided via the heat transfer fluid to fluid duct <NUM> to provide enough thermal energy to maintain contact lens <NUM> above the ambient dew point.

Referring now to <FIG>, a flow chart of selected elements of a method <NUM>, outside the scope of the present claims. for performing ophthalmic surgery, as described herein, is depicted in flowchart form. Method <NUM> describes steps and procedures for using an anti-fogging device with contact lens <NUM> (see <FIG>, <FIG>) to view the fundus of an eye and to enable further surgical procedures based on the view of the fundus. It is noted that certain operations described in method <NUM> may be optional or may be rearranged in different arrangements. Method <NUM> may be performed by a surgeon or by other medical personnel. In some arrangements, at least certain portions of method <NUM> may be automated, for example using regulated control of temperature, as described above.

Method <NUM> which is outside the scope of the claims, may begin, at step <NUM>, by positioning a first optical axis of a surgical microscope along a second optical axis of an eye of a patient. At step <NUM>, an interior portion of the eye is viewed using a contact lens in contact with the eye. At step <NUM>, an anti-fogging device coupled to the contact lens is activated, such that the anti-fogging device delivers thermal energy to the contact lens.

Claim 1:
A contact lens assembly for ophthalmic surgery, the contact lens assembly comprising:
a contact lens (<NUM>);
an anti-fogging device (<NUM>) coupled to the contact lens, wherein the anti-fogging device delivers thermal energy to the contact lens while the contact lens is in use during ophthalmic surgery to view an interior portion of an eye of a patient using a surgical microscope;
characterized in that:
the anti-fogging device further comprises a handle (<NUM>) for supporting the contact lens on the eye during surgery; and
wherein electrical energy to generate the thermal energy is delivered via lead lines (<NUM>) attached to the handle.