Surgery – Devices transferring fluids from within one area of body to...
Patent
1996-12-11
1999-03-09
Willse, David H.
Surgery
Devices transferring fluids from within one area of body to...
623 4, A61F 214
Patent
active
058793194
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention concerns an implant intended to be inserted in the sclera of the eye following a sclerotomy operation with or without trabeculectomy.
BACKGROUND OF THE INVENTION
At the present time glaucoma is treated in the most serious cases by a surgical operation known as a trabeculectomy. This operation consists, following conjunctival disinsertion, of making an opening in the sclera by cutting out a scleral flap (division in the planes of the sclera as far as the trabeculum) and incising the trabeculum to enable the aqueous humor contained in the anterior chamber to flow out, thus reducing the intra-ocular pressure and limiting the pathological consequences of glaucoma. Such an operation, which has been performed for about fifteen years, generally produces a temporary improvement, but in time, healing of the scleral flap is liable to obstruct the flow of aqueous humor and a renewed increase in the intra-ocular pressure is then noted.
An attempt has been made to overcome this defect by applying antimitotic substances on the scleral flap so as to retard healing. However, the results are variable and it is even possible to observe an excessive flow of aqueous humor which can bring about too great a fall in the intra-ocular pressure.
Another type of operation is currently practiced for treating glaucoma. It consists of putting a valve in place associated with a tube which emerges in the anterior chamber to enable aqueous humor to flow out in the case of an increase in pressure in this chamber. This technique has disadvantages however. In the first place, it requires a complex operation affecting the anterior chamber, with the risk of a deleterious effect on the corneal endothelium, and surgeons who are used to trabeculotemies are reluctant to perform this type of complex and risky surgical operation. Moreover, the tube tends to block up so that the efficiency of the device, which is good after it has been put in place, decreases rapidly with time. In addition, the pipe is sometimes expelled from the anterior chamber. It should be noted that these valves have a relatively complex structure which makes them costly to manufacture.
In addition, several publications have proposed novel techniques which are at the experimental stage (or have remained at the experimental stage on account of basic defects) and which consist of inserting an implant under the scleral flap with a view to preventing the flow of aqueous humor through the incision in the trabeculum from being obstructed too rapidly.
A first technique is described in the following publication "Hyun Bong Bae et al., A Membranous Drainage Implant in Glaucoma Filtering Surgery: Animal Trial, Kor. J. Ophthalmol., vol. 2, 1988, 49-56". It consists of placing a hydrophobic membrane under the scleral flap which penetrates into the anterior chamber by means of an incision in the trabeculum. By virtue of its hydrophobic nature, this membrane opposes the formation of fibroses close to its surface and enables aqueous humor to flow out along it. However the permanent flow thus produced is small and the presence of such a membrane appears to be insufficient to restore the intra-ocular pressure to a normal value. Moreover, its insertion involves an operation on the anterior chamber with risks to the corneal endothelium, this operation being much more delicate than a simple trabeculectomy as already indicated.
The following publication: "M. Kamoun et al., Microtrabeculoprothese, Ophtalmologie, 1988, vol. 2, 227-229", describes a trabeculoprosthesis made of a very hydrophilic porous hydrogel which is put in place in the dry state in the sclera so as to penetrate the incision in the trabeculum by a tapered part. Hydration causes the hydrogel to swell and the incision to be hermetically sealed. The aqueous humor then flows out through pores in the material from the anterior chamber to the sclera. This filtration though a porous material of this type brings about a reduction in the intra-ocular pressure. However, the aforementioned defect, which
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Nancy Michel, "A wick that promotes fluid drainage treats glaucoma successfully in Russia", Ocular Surgery News, 1993, vol. 11, No. 23, p. 26.
M. Kamoun et al., "Microtrabeculoprothese", Ophtalmologie Vo. 2, 1988, pp. 227-229.
Hyun Bong Bae et al., "A Membranous Drainage Implant in Glaucoma Filtering Surgery: Animal Trial", Korean J. Ophthalmol, vol. 2, 1988, pp. 49-56.
Feurer Bernard
Payrou Viviane
Pynson Joel
Chauvin Opsia
Willse David H.
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