Surgery – Devices transferring fluids from within one area of body to...
Reexamination Certificate
2000-02-09
2001-05-29
Kennedy, Sharon (Department: 3763)
Surgery
Devices transferring fluids from within one area of body to...
Reexamination Certificate
active
06238364
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to lacrimal silicone stents and a method of inserting the same, and more particularly, to asymmetric lacrimal silicone stents having a very large diameter segment which is inserted transnasally.
2. Description of the Prior Art
The lacrimal gland produces the aqueous layer of the tear film. The orbital portion of the lacrimal gland is located in the superior temporal orbit. Ductules from the main lacrimal gland pass through the adjacent palpebral lacrimal gland to empty in the superior conjunctival cul-de-sac which is on the posterior surface of the superior upper lid. Accessory lacrimal glands in the upper and lower lids also contribute to tear production.
The tears bathe the eye and then flow into the upper and lower puncta, which are located on the medial upper and lower lid margins. The tears then drain through the superior and inferior canaliculi, common canaliculus, lacrimal sac, and down the nasolacrimal duct into the nose. The nasolacrimal duct can become obstructed either congenitally or as an acquired obstruction in adulthood. When the nasolacrimal duct becomes obstructed, tears can no longer drain from the surface of the eye through the lacrimal system into the nose. The tears therefore well up over the eyes and spill over the lids onto the face. The patient has to constantly dab the eyes with a tissue. In addition, tears stagnate in the lacrimal sac which allows bacteria to multiply. The lacrimal sac then becomes infected (dacryocystitis). Dacryocystitis causes the lacrimal sac to become swollen, red and painful. Pus exudes from the lacrimal sac through the canaliculi onto the eye. This results in purulent material constantly covering the eye. In time, the dacryocystitis does not respond to antibiotics and surgery becomes necessary.
Dacryocystorhinostomy (DCR) is the surgery used to correct nasolacrimal duct obstruction. In a DCR, a new opening (ostium) is created between the lacrimal sac and the nose. This allows tears to flow from the lacrimal sac through the DCR ostium into the nose. An open or incisional DCR requires an incision on the side of the nose. In an open DCR, a large DCR ostium is created by making a 17 mm. plus opening in mucosa and bone. This procedure has significant morbidity, a prolonged recovery, and the threat of scarring and hemorrhage. In contrast, a transnasal endoscopic DCR has must less morbidity, no incision, and a quick recovery time. An endoscope DCR may be performed using lacrimal or sinus surgery instruments, a laser, or a balloon catheter. The endoscopic DCR ostium is smaller (5 to 9 mm.) than that of an open DCR. Because the DCR ostium is only 5 to 9 mm. (0.1969 to 0.354 inch) in diameter, a stent is required to keep the DCR ostium open after surgery. Otherwise postoperative inflammation and scarring may cause it to close.
In selecting a stent for this purpose, it is necessary to keep in mind the dimensions and properties of the canaliculi which are the narrowest part of the lacrimal system, as well as the properties of the silicone stent material and the technique for inserting the stent. An adult patient has canaliculi which are about 0.5 mm. (0.01969 inch) in diameter. It is possible however, to employ silicone tube stents which are somewhat larger in outer diameter, because there is a certain amount of resiliency, and give, in the tissue, and because tubular silicone stents tend to become thinner when placed under tension as they are pulled through the lacrimal system. The size of the silicone stent which can be used reaches an upper limit for the largest diameter stent which can be pulled through the canaliculi readily and without damaging the canaliculi. I have found that the largest diameter stent which can be so used is 0.053 inch.
It has been proposed in the prior art to use a silicone tube stent with a uniform diameter of 0.020 inch. However, this is too small a diameter to keep the endoscopic DCR ostium open.
A larger diameter tube with a diameter of 0.037 inch has also been used in the prior art. This larger diameter tube is still too small and soft to stent the balloon DCR ostium. Furthermore, the larger diameter causes irritation and epithelial defects on the cornea and conjunctiva where the tube lays against the eye in the medial canthus. It may also obstruct the drainage through the tiny canaliculi. The silicone tube comes with an attached rigid metal probe on each end. To place the tube in the lacrimal system, the probe is pushed through the punctum, canaliculus, lacrimal sac, DCR ostium into the nose. The probe is grasped in the nose and pulled down the nose and out the external naris. The probe pulls the attached silicone tube through the punctum, canaliculus, lacrimal sac and DCR ostium into the nose. The opposite end of the tube with its attached probe is brought through the opposing punctum and canaliculus, the lacrimal sac, and the DCR ostium into the nose. The probe attached to the opposite end is grasped in the nose and brought down the nose and out the external naris. The probe pulls the attached silicone tube through the punctum, canaliculus, lacrimal sac, and DCR ostium into the nose. The two ends of the tube are then cut 1½ cm. inside the external naris. The tube is left in place for about six months.
In an effort to stent the endoscopic DCR ostium with a larger diameter stent, which is too large to pass through the canaliculi, a short, more rigid stent, which can be placed from the nasal cavity, has been proposed. The short, large diameter stent is pushed from inside the nose through the endoscopic DCR ostium into the lacrimal sac. When in place, the stent extends from the lacrimal sac through the endoscopic DCR ostium into the nose. A number of such stents have been tried. They have had several problems. They are difficult or impossible to push into place. They frequently fall out shortly after surgery. Attempts to fixate them on a silicone tube are only minimally helpful. These stents can induce inflammation, infection and scarring.
I previously designed a “fat” silicone tube that has a large diameter in the portion that stents a balloon DCR ostium. An example is shown in my copending application Ser. No. 08/547,792, filed Oct. 25, 1995. It has a small diameter in the segment that lies against the eye. The large diameter portion (usually 0.052 inch in diameter) cannot be pulled through the small diameter puncta and canaliculi without slipping off the probe. Therefore, each end of the tube has a long small diameter portion. The small diameter ends of the tube are attached to the probe. After the probe is grasped in the nose, it is pulled down the nose and pulls the attached small diameter end of the tube through the puncta, canaliculi, lacrimal sac, balloon DCR ostium into the nose. The small diameter end of the tube is then grasped in the nose. As the small diameter segment is pulled down the nose, it pulls the attached larger diameter portion of the tube through the narrow puncta and canaliculi, the larger lacrimal sac and DCR ostium into the nose. This is done with each end of the tube. When in place, the ends of the tube are cut 1½ cm. inside the external naris. The larger diameter segment of the tube will lie in the distal canaliculi, lacrimal sac, and balloon DCR ostium extending into the nose. The small diameter end of the tube will have been cut off.
However, there are two problems with this “fat” tube. In some patients it can be difficult to pull the large diameter segments through the canaliculi. If the canaliculi are somewhat narrow, the tubes may break when the surgeon exerts traction on the narrow distal segment in the nose in an attempt to pull the fat segment through the canaliculi into the lacrimal sac. A second problem is that pulling the large diameter segments through the canaliculi may stretch the canaliculi enough to damage them and cause fibrosis (scarring). In this case, the canaliculi will become stenotic (narrow) and obstruct tear drainage after the tube is removed. This results in tearin
Field Milton M.
Kennedy Sharon
Serke Catherine
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