Surgery – Instruments – Light application
Patent
1986-09-25
1990-11-27
Cohen, Lee S.
Surgery
Instruments
Light application
606 10, 606 17, 128395, 21912175, 21912183, A61N 506
Patent
active
049733303
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a surgical apparatus for modifying the curvature of the eye cornea. The apparatus may be utilized both with corneas which are in situ within a living being as well as with corneas which have previously been removed from the patient's body.
It is known that certain disorders, such as myopia, hypermetropia and astigmatism, may be treated by modifying the curvature of the cornea. Furthermore, other disorders, such as aphakia, may be treated at least partly by correction of said curvature. Consequently, methods for modifying the curvature of the cornea have already been thought of.
Such methods are essentially of two types:
The first consists of the steps of: (1) removing with the aid of a mechanical cutting instrument, a plane-convex lens-shaped body of material from the cornea, (2) freezing this lens to render it solid and (3) machining, by means of a lathe, said solidified lens in order to eliminate therefrom a zone in the form of a convex lamina of variable thickness. After machining, the machined lens is thawed, then sewn back at its initial location. Such a method is long, expensive and traumatic for the patient. Moreover, this method can only be used to treat disorders wherein the extent to which the radius of curvature of the cornea is suboptimized is constant about the optical axis of the eye, such as myopia and hypermetropia, but is of no usefulness with disorders such as astigmatism wherein the amount of corneal material which must be removed in order to optimize the shape of the cornea does not present any symmetry of revolution about the optical axis;
in the second type of method, a series of radial slots are made in the cornea, outside of the optical zone, by means of a bistoury or a laser beam. As a result of these slots, the incized part of cornea flattens, consequently modifying the general curvature. Although less traumatic than the methods of the first type, those of the second type remain violent due to necessary scarifications of the cornea. Moreover, the possible applications for these latter methods remain limited.
In contrast to the above-stated methods, the article entitled "Excimer laser surgery of the cornea" dated Sept. 21, 1983 and appearing in the Journal "AMERICAN JOURNAL OF OPHTHALMOLOGY", Vol. 96, No. 6, pages 710 to 715 of December 1983, by STEPHEN L. TROKEL, R. SRINIVASAN and BODIL BRAREN discloses the use of an excimer laser to modify the corneal profile by photodecomposition. In this article, the use of a source of ultraviolet radiation having a wavelength equal to 0.193 micrometer (193 nanometers) in order to modify the curvature of the cornea is disclosed. This method calls for forming on said cornea, with the aid of said radiation, a circular photoradiant zone "of which the intensity varies from the center towards the periphery, with the result that more matter is removed either at the center or on the periphery, as a function of the distribution of light". The curvature of the cornea may thus be increased or reduced.
This latter method is particularly advantageous, but is difficult to carry out, as it calls for varying the light intensity within the photoradiant zone in accordance with the desired corneal curvature. Putting this method into practice appears difficult if not impossible.
It is an object of the present invention to overcome the drawbacks of these known methods. The present invention relates to a surgical apparatus for modifying the curvature of the cornea in a non-traumatic, rapid and easy manner in order to treat disorders as different as myopia, hypermetropia, aphakia, and astigmatism.
Towards these ends, a surgical apparatus for modifying at least partly the curvature of the eye cornea by ablation of a zone therefrom having the form of a lenticular lamina of radially variable thickness is disclosed. The apparatus comprises a source of light capable of emitting a beam whose wavelength is close to 0.2 micrometer (i.e., about 200 nm) in order to produce the desired photodecomposition of the corneal matter, as well as an opt
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Arneodo Jacques
Azema Alain
Botineau Jean
Crozafon Philippe
Moulin Gerard
Cohen Lee S.
Shay David
Synthelabo
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