Patent Application
20110248671
The present invention relates to a power system that is implantable in the eye.
Glaucoma, a group of eye diseases affecting the retina and optic nerve, is one of the leading causes of blindness worldwide. Glaucoma results when the intraocular pressure (IOP) increases to pressures above normal for prolonged periods of time. IOP can increase due to an imbalance of the production of aqueous humor and the drainage of the aqueous humor. Left untreated, an elevated IOP causes irreversible damage the optic nerve and retinal fibers resulting in a progressive, permanent loss of vision.
The eye's ciliary body epithelium constantly produces aqueous humor, the clear fluid that fills the anterior chamber of the eye (the space between the cornea and iris). The aqueous humor flows out of the anterior chamber through the uveoscleral pathways, a complex drainage system. The delicate balance between the production and drainage of aqueous humor determines the eye's IOP.
Open angle (also called chronic open angle or primary open angle) is the most common type of glaucoma. With this type, even though the anterior structures of the eye appear normal, aqueous fluid builds within the anterior chamber, causing the IOP to become elevated. Left untreated, this may result in permanent damage of the optic nerve and retina. Eye drops are generally prescribed to lower the eye pressure. In some cases, surgery is performed if the IOP cannot be adequately controlled with medical therapy.
Only about 10% of the population suffers from acute angle closure glaucoma. Acute angle closure occurs because of an abnormality of the structures in the front of the eye. In most of these cases, the space between the iris and cornea is more narrow than normal, leaving a smaller channel for the aqueous to pass through. If the flow of aqueous becomes completely blocked, the IOP rises sharply, causing a sudden angle closure attack.
Secondary glaucoma occurs as a result of another disease or problem within the eye such as: inflammation, trauma, previous surgery, diabetes, tumor, and certain medications. For this type, both the glaucoma and the underlying problem must be treated.
A number of different implantable drainage devices (e.g. Ahmed valve, Baerveldt implant) have been developed to treat late stage glaucoma. These implants are quite large—about 12 mm by 12 mm by 1.5 mm—and are implanted under the conjunctiva of the human eye. As such, the eye can tolerate these large implants. As technology is advancing, newer glaucoma implants are being developed. It would be desirable to enhance the functionality of these implants by adding a power system. In order to power such a device, it would desirable to have a power system that is configured for implantation into the eye.
In one embodiment consistent with the principles of the present invention, the present invention is an implantable ophthalmic power system. The power system has a power source and an enclosure. The enclosure surrounds the power source. The enclosure is configured to be implanted under the conjunctiva of the eye.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide further explanation of the invention as claimed The following description, as well as the practice of the invention, set forth and suggest additional advantages and purposes of the invention.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the invention and together with the description, serve to explain the principles of the invention.
Reference is now made in detail to the exemplary embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used throughout the drawings to refer to the same or like parts.
Implantable power system 200 has dimensions of about 12 millimeters by 12 millimeters wide by 1.5 millimeters thick. In other embodiments of the present invention, the dimensions of implantable power system 200 are less than 12 millimeters by 12 millimeters wide. The thickness of implantable power system 200 is typically between one and two millimeters, although thicknesses of less than one millimeter may be achieved.
Implantable power system 300 has a diameter of about 12 millimeters and is about 1.5 millimeters thick. In other embodiments of the present invention, implantable power system 300 is less than 12 millimeters in diameter. The thickness of implantable power system 300 is typically between one and two millimeters, although thicknesses of less than one millimeter may be achieved.
Implantable power systems 200 and 300 have a curved profile that fits the curvature of the human eye. In other words, the bottom surface of implantable power system 200 or 300 rests on the surface of the sclera (when implanted under the conjunctiva). The radius of curvature is approximately 8 to 16 millimeters. In one embodiment of the present invention, the implantable power system may be made using a cross pattee configuration. A cross pattee configuration allows for the radius of curvature to be more easily implemented. In a cross pattee configuration, wedges of material are removed from a sheet of material so that when the edges of the wedges are placed adjacent to each other, a radius of curvature is approximated.
Implantable power systems 200 and 300 may be rigid or flexible. When rigid, implantable power systems 200 and 300 may be made of a biocompatible material such as stainless steel. In this manner, a stainless steel case with the above dimensions contains the components of the power system. In other embodiments of the present invention, the case may be made with any rigid material and then coated with a biocompatible material such as polypropylene or silicone. In yet other embodiments of the present invention, the case may be made directly made from a biocompatible polymeric material such as polypropylene or silicone. Since the final form factor can be very similar to existing implantable tube-to-plate drainage devices (e.g. Ahmed valve, Baerveldt implant), the packaged power system can also serve as the plate portion of such a device.
When flexible, implantable power systems 200 and 300 may be made of a biocompatible material that can be shaped to conform to the curvature of the human eye. In this case, the components inside the power systems 200 and 300 are also flexible—such as a capacitor array on a flexible substrate or a flexible thin film battery.
In one embodiment of
In another embodiment of the present invention a thermoelectric module can be used instead of battery 720. A thermoelectric module converts heat conducting out of the body into electrical current using the thermoelectric effect or Peltier effect. Under normal conditions, heat conducts out of the eye through the eyelid and into the air. As such, the globe of the eye is at a higher temperature that the surface of the eye that contacts the outside environment. A thermoelectric module can harness this temperature difference to create electrical current. When implanted under the conjunctive, the hot side of the thermoelectric module can be placed on the surface of the sclera, and the cold side of the module can be placed in contact with the conjunctiva. The thermoelectric module converts the temperature difference into electrical current.
In yet another embodiment of the present invention, a solar cell module can be used instead of battery 720. The solar cell module converts ambient light into electrical current. Since the eye is exposed to ambient light during most of the day, this light can be harnessed by a solar cell module. In such a case, the light collecting side of the solar cell module is implanted under the conjunctiva. Since the conjunctiva is clear, light can pass through it and strike the solar cell module. The case of the implantable power system 200, 300 can be clear as well so that light is allowed to strike the solar cell module. In another embodiment of the present invention, the light collecting face of the solar cell module is integrated into the enclosure such that it collects light that travels through the conjunctiva.
Electronics modules, 810, 820, and 910 function to operate the power source, in this case, capacitor arrays 830 and 930, respectively. In one example, electronics modules perform charging and discharging functions, power source maintenance functions, and the like.
The implantable power system 200, 300 is implanted into the human eye under the conjunctiva and on top of the sclera. A surgeon makes an incision in the conjunctiva near the limbus. A pocket is created by separating the conjunctiva from the sclera. The implantable power system is placed in this pocket, and the conjunctiva is sutured. In an alternate procedure, the surgeon implants the implantable power system in a pocket made in the sclera. In this case, the surgeon makes an incision in the conjunctiva and a partial incision in the sclera near the limbus. A pocket is formed in the sclera by separating layers of scleral tissue. The implantable power system is placed in the pocket, and the incisions are closed.
From the above, it may be appreciated that the present invention provides a power system that can be implanted in the eye. The present invention provides a power system that has a form factor suitable for implantation in the subconjunctival space. The present invention is illustrated herein by example, and various modifications may be made by a person of ordinary skill in the art.
Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.
