Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
1999-06-21
2001-09-18
Seidel, Richard K. (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S035000, C604S140000, C604S141000
Reexamination Certificate
active
06290690
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally pertains to apparatus and methods for providing simultaneous viscous fluid injection and aspiration in a surgical system. More particularly, but not by way of limitation, the present invention pertains to apparatus and methods for injecting a long-term viscous fluid tamponade into the posterior segment of the eye while simultaneously aspirating a short-term viscous fluid tamponade out of the eye during vitreoretinal surgery.
DESCRIPTION OF THE RELATED ART
In a healthy human eye, the retina is physically attached to the choroid in a generally circumferential manner behind the pars plana. The vitreous humor, a transparent jelly-like material that fills the posterior segment of the eye, helps to cause the remainder of the retina to lie against, but not physically attach, to the choroid. A helpful analogy is to imagine the choroid as the walls of a swimming pool. The retina is like a wallpaper that is pressed against the walls of the swimming pool by the water in the pool, but is only physically attached to the walls at the top of the pool.
Sometimes a portion of the retina becomes detached from the choroid. Other times a portion of the retina may tear, allowing aqueous humor, and sometimes vitreous, to flow between the retina and the choroid. Both of these conditions result in a loss of vision.
To surgically repair these conditions, a surgeon typically inserts a vitrectomy probe into the posterior segment of the eye via an incision through the sclera in the pars plana. Such an incision is called a scleratomy. The surgeon typically also inserts a fiber optic light source and an infusion cannula into the eye via similar incisions, and may sometimes substitute an aspiration probe for the vitrectomy probe. While viewing the posterior segment under a microscope and with the aid of the fiber optic light source, the surgeon cuts and aspirates away vitreous using the vitrectomy probe to gain access to the retinal detachment or tear. The surgeon may also use the vitrectomy probe, scissors, a pick, and/or forceps to remove any membrane that has contributed to the retinal detachment or tear. During this portion of the surgery, a saline solution is typically infused into the eye via the infusion cannula to maintain the appropriate intraocular pressure.
Next, many surgeons inject a perfluorocarbon liquid into the posterior segment of the eye to cause the detached or torn portion of the retina to flatten against the choroid in the proper location. Once the detached or torn portion of the retina is properly located, the surgeon uses a diathermy probe or a laser to fuse portions of the detached retina in place.
Unfortunately, perfluorocarbon liquids are toxic when left in the eye for a period of weeks. Since a retinal tear or detachment takes a period of weeks to re-attach after the above-described surgical procedure, the short-term perfluorocarbon liquid tamponade must be removed from the eye at the latter portion of the surgical procedure and replaced with a long-term tamponade. This long-term tamponade can be an air/gas mixture or a viscous fluid, such as silicone oil. If silicone oil is used, it too must be extracted from the eye after the retina re-attaches because it is toxic when left in the eye for a period of months.
Conventionally, surgeons employ several techniques to perform this replacement of perfluorocarbon liquid with silicone oil, which is sometimes called a “fluid/fluid exchange”. First, the surgeon may use a conventional vitreoretinal surgical system to inject silicone oil via a system generated injection pressure and an infusion cannula. An exemplary system is the Accurus® surgical system sold by Alcon Laboratories, Inc. of Fort Worth, Tex. As the silicone oil is injected, pressure increases in the eye. The increased pressure in the eye causes the perfluorocarbon liquid to passively flow into an extrusion cannula connected to the aspiration probe. The aspiration probe removes the perfluorocarbon liquid from the eye. Unfortunately, this technique requires the use of larger diameter (e.g. straight 20 gage) extrusion cannulas to allow sufficient passive flow without excessively elevated intraocular pressure. In contrast, surgeons prefer to use tapered and/or soft tip extrusion cannulas due to the additional level of safety provided should they accidentally come in contact with the retina.
Second, a surgeon may use such a conventional vitreoretinal surgical system to inject silicone oil via a system generated infusion pressure and an infusion cannula. As the intraocular pressure increases, the surgeon switches the mode of operation of the surgical system so that it provides vacuum for the aspiration probe instead of injection pressure for the infusion cannula. The surgeon then utilizes the aspiration probe with extrusion cannula to aspirate perfluorocarbon liquid from the eye to counteract the above-described rise in intraocular pressure. Next, the surgeon reconfigures the surgical system for injection pressure and injects more silicone oil into the posterior segment of the eye. This cycling between injecting silicone oil and aspirating perfluorocarbon liquid is continued until all the perfluorocarbon liquid is replaced with silicone oil. In this technique, the surgeon visually monitors the eye in an attempt to prevent the intraocular pressure from rising to a dangerously high level (a “hard eye” condition) or a dangerously low level (a “soft eye” condition). In addition, it is important to note that this cycling is required because conventional vitreoretinal surgical systems are not capable of supplying simultaneous injection and aspiration of viscous fluids. However, even when this technique is performed successfully, the intraocular pressure can vary above and below a desired intraocular pressure. This variance of the intraocular pressure may cause difficulty for the surgeon during the procedure, can be detrimental to the patient, and is especially prevalent with the preferred use of tapered and soft tip extrusion cannulas.
Third, the surgeon may employ the technique of using a conventional vitreoretinal surgical system and an aspiration probe to aspirate perfluorocarbon liquid, and a second, separate system to inject silicone oil. The use of two systems allows the simultaneous injection and aspiration of viscous fluids into the eye. However, the use of two systems requires the surgeon to operate and control both systems simultaneously, which can be difficult. The surgeon may be forced to utilize additional staff to help with the operation of at least one of the systems.
As mentioned hereinabove, different methods of tamponading the retina after vitreoretinal surgery exist that do not require the use of perfluorocarbon liquids. For example, the surgeon may utilize an air/gas mixture as a long-term tamponade. In this technique, the surgeon infuses air while all of the saline, resulting from the vitrectomy process, is aspirated. The air acts to re-position the retina against the choroid. A mixture of air and gas (typically a perfluorocarbon gas) is then injected into the air-filled eye replacing the infused air. The air/gas mixture is of a specific proportion resulting in an expanding air/gas bubble having an expansion rate that closely matches the rate at which air leaks from the eye. The air/gas bubble helps prevent regenerated aqueous humor from wetting the retina before it has had sufficient time to re-attach. The bubble typically lasts several days. Unfortunately, the use of an air/gas mixture as a long-term tamponade requires a very compliant patient. For example, patients must hold their head in certain positions for several hours a day to insure that the air/gas bubble prevents aqueous humor from wetting the retina. This type of long-term tamponade is therefore not suitable for elderly, young, and mentally disabled patients, or patients requiring air travel. In addition, during large retinal tear or detachment procedures, such “fluid/air” and “air/gas” exchanges can result in slippage of the retina, procedural compl
Finlay Russell L.
Huculak John C.
Zaleski, II Richard L.
Alcon Manufacturing Ltd.
Lee W. David
Rodriguez Cris
Seidel Richard K.
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