Surgery – Devices transferring fluids from within one area of body to... – With flow control means
Reexamination Certificate
1998-06-16
2001-10-23
Kamm, William E. (Department: 3762)
Surgery
Devices transferring fluids from within one area of body to...
With flow control means
C604S008000, C128S887000, C623S011110
Reexamination Certificate
active
06306114
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates broadly to medical canalicular inserts. More particularly, this invention relates to canalicular plugs which are placed into the punctal opening or the lacrimal duct to prevent lacrimal fluid from flowing through the lacrimal duct.
2. State of the Art
A variety of eye problems are related to an insufficient volume of tears on the surface of the eyes. The most common is keratoconjunctivitis sicca, also known as dry eyes. Contact lens problems are also often provoked by a lack of tear volume. A common cause for the insufficient tear volume is the drainage of tear fluid through the punctal opening of the nasal lacrimal duct and into the nasal passage, thereby removing the fluid from where it is needed at the eye surface. Furthermore, drainage of tear fluid through the nasal lacrimal duct into the nasal passage is believed to be the cause or associated with several additional problems such as post nasal drip, sinusitis, allergies, headaches, and snoring.
A number of methods for closing the punctal opening have been used to prevent drainage of tears through the nasal lacrimal duct, including suturing, laser sealing, and plugging. Plugging with a canalicular plug, such as a punctum plug or a lacrimal plug, is the least severe solution, is relatively inexpensive, and is being performed with increasing frequency.
Referring to prior art
FIG. 25
, a punctum plug
910
typically is an elongate member having a proximal head
912
, a relatively larger distal body
914
for occluding the lacrimal duct
916
, and a relatively narrower rigid shaft
918
therebetween. The plug is usually provided with a proximal axial bore
920
for receiving a cylindrical insertion tool. In the punctum plug insertion procedure, an insertion tool is positioned into the bore
920
of the plug, the body of the plug is directed at the punctal opening
922
of the lacrimal duct
916
, and force is applied to the insertion tool to move the body
914
of the plug through the punctal opening
922
and into the vertical puncta
924
and lacrimal duct
916
. Once the plug is in the vertical puncta and lacrimal duct, the insertion tool is removed. The plug is fully inserted when the head seats against the tissue at the punctal opening and the body seats within the lacrimal duct so as to block the passage of tear fluid and thereby retain tear fluid at the surface of the eye. Similarly, lacrimal plugs which seat entirely within the lacrimal duct (and below the punctal opening) are also known.
It has been found that prior art punctum and lacrimal plugs, while providing some benefit often do not provide satisfactory occlusion of the lacrimal duct. Tear fluid tends to flow through the interstices between the body of the plug and the tissue of the vertical puncta of the nasal lacrimal duct. One proposed prior art solution of this problem has been to provide an enlarged distal body to the plug. However, the larger distal body is difficult to insert through the relatively small punctal opening.
In addition, with prior art canalicular plugs, completely occluding the lacrimal duct can provoke other detrimental effects. For example, when a patient has a plug implanted in his or her lacrimal duct, simple acts such as sneezing or nose blowing can cause a momentary pressure differential to occur about the plug. That is, referring to prior art
FIG. 25
, the lacrimal duct
916
on the body side of the plug (below body
914
) is subject to increased pressure relative to the head side of the plug (above head
914
). This pressure differential can result in the plug being forced up and inadvertently dislodged from the puncta. Other activities, such as eye rubbing and ear-popping (e.g., after scuba diving or flying) can similarly cause a pressure differential and result in inadvertent expulsion of the plug from the lacrimal duct.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a canalicular plug which occludes the flow of tears through the lacrimal duct.
It is another object of the invention to provide a canalicular plug which prevents a pressure differential from occurring about the proximal and distal ends of the plug and, as such, is not readily subject to unintentional dislodgement from the lacrimal duct.
It is also an object of the invention to provide a canalicular plug which is designed to facilitate insertion into the lacrimal duct.
In accord with these objects which will be discussed in detail below, a canalicular plug is provided which generally includes a proximal head, a distal body, and a shaft between the head and the body. The plug has a throughbore provided with a valve. The throughbore is preferably stepped, having a relatively larger proximal portion for receiving an insertion tool and a relatively smaller distal portion provided with the valve. The plug is preferably made from a resilient biocompatible material, and the valve is preferably integrally molded with the plug and designed to open only when subject to a relatively large pressure differential across the plug.
According to a preferred embodiment of the invention, the distal portion of the canalicular plug includes at least one slot dividing the distal portion into a plurality of resilient portions which are biased apart, yet inwardly compressible about the slot. When compressed together, the distal ends of the resilient portions together form a generally conical or frustoconical shape which is smaller in cross-sectional area than the non-compressed body portion, and thereby facilitates insertion. The body includes at least one foldable pleat which uninterruptingly connects the upper and peripheral areas of the resilient portions together.
Once the plug is seated in the lacrimal duct, the head and body portions occlude the passage of tear fluid therethrough. The valve prevents tear fluid from passing from the eye through the stepped throughbore and into the lacrimal duct. However, when pressure builds up within the lacrimal duct, e.g., because of sneezing, ear popping, etc., the valve opens, thereby permitting the pressure to equalize and preventing the plug from dislodging. According to particular embodiments of the invention, the valve is preferably a flapper valve, a duck bill valve, or a slit valve, although other valve-types can be used.
According to additional embodiments, the canalicular plug has either a compressible proximal head and a shaft provided with a valve, or a shaft provided with a valve and a relatively larger body portion. In both additional embodiments, the canalicular plug is adapted for relatively deeper lacrimal duct insertion.
Additional objects and advantages of the invention will become apparent to those skilled in the art upon reference to the detailed description taken in conjunction with the provided figures.
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Freeman C. Curtis
Webb Nicholas J.
Bianco Patricia
Eagle Vision, Inc.
Gallagher Thomas A
Gordon David P.
Jacobson David S.
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