FENESTRATED LENS FOR INCREASED
TEAR FLOW AND METHOD OF MAKING
This application claims priority of Provisional Application No. 60/236,252, filed Sep. 28, 2000.
FIELD OF INVENTION
This invention relates to contact lenses and in particular to ways of increasing the flow of oxygen and nutrient laden tears through contact lenses to the surface of a wearer's cornea.
DESCRIPTION OF THE PRIOR ART
Hard contact lenses have the advantages of longevity, biocompatability, strength, durability, wettability and the ability to compensate for some types of astigmatism. However, conventional hard contact lenses also act as a barrier to reduce the flow of oxygen and nutrients to the corneal surface, which may lead to oedema and other undesirable effects. Soft contact lenses have been developed which have a higher oxygen permeability than hard contact lenses and thereby reduce the incidence of oedema and similar effects. However, even oxygen permeable contact lenses reduce the flow of oxygen and nutrient laden tears to the cornea. This reduced flow of tears can result in the accumulation of metabolic products from corneal cells behind the lens, growth of bacteria behind the lens, and general wearer discomfort.
One method previously disclosed to partially alleviate these problems has been to "fenestrate" the contact lenses by creating holes passing completely through the lenses to allow bulk tear flow and the transfer of dissolved oxygen through the lenses and to the eye surface. Various techniques have been proposed for the fenestration of contact lenses. For example, one system (see e.g., U.S. Pat. No. 3,227,855) uses a spark to locally burn a small hole through the lens. Others (see e.g., U.S. Pat. Nos. 3,833,786 and 3,971,910) describe laser based systems in which a concentrated beam is used to burn through the lens to produce the holes. Still other systems use drills to mechanically bore holes through the lens (see e.g., U.S. Pat. No. 6,101,219)
Conventional fenestrated contact lenses have holes intended to provide bi-directional diffusion of oxygen and/or flow of tears. However, by their passive and non-directional nature, these contact lenses have a less than optimal tear flow which can potentially result in low tear and oxygen flow to certain areas of the cornea. Their fenestrations also have a tendency to clog resulting in impaired tear flow. There is clearly a need for a fenestrated contact lens having an improved tear flow to improve corneal health and reduce the risk of corneal damage due to oxygen or nutrient starvation of the corneal cells.
Accordingly, it is an object of the present invention to provide a fenestrated contact lens having an increased oxygen and tear flow to the corneal surface.
It is another object of the present invention to provide a fenestrated contact lens that will direct tear flow in a desired pattern to optimize tear flow to the cornea.
It is yet another object of the present invention to provide a method for producing fenestrated contact lenses having increased tear flow characteristics.
Other objects, aspects, and advantages of the present invention will be apparent to those skilled in the art from a reading of the following detailed disclosure of the invention.
BRIEF DESCRIPTION OF THE INVENTION
The above objectives are accomplished according to the present invention by providing a fenestrated contact lens having increased tear flow. The fenestrated contact lens
5 includes a lens body adapted for placement adjacent a surface of an eye which has an inner surface and an outer surface. The lens body has a first plurality of fenestrations extending therethrough which are biased to direct a flow of tear fluid from a first location between the surface of the
10 wearer's eye and the inner surface of said contact lens to a second location adjacent the outer surface of the contact lens. The lens body also includes a second plurality of fenestrations extending therethrough, which are biased to direct a flow of tear fluid from a third location adjacent the outer surface of the contact lens to a fourth location between the surface of the eye and the inner surface of said contact lens.
BRIEF DESCRIPTION OF THE FIGURES
20 The construction and design to carry out the invention will hereinafter be described together with other features thereof. The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawings forming a part thereof, wherein 25 an example of the invention is shown and wherein:
FIG. 1 is a cross-sectional diagram illustrating a preferred embodiment of the fenestrated lens of the present invention.
FIG. 2 is a front view of a fenestrated lens in accordance 30 with the embodiment of FIG. 1.
FIGS. 3A and 3B are front views of fenestrated lenses having fenestration patterns in accordance with alternative embodiments of the present invention.
FIG. 4 is a cross-sectional view of a tapered fenestration 35 providing directional flow in accordance with a preferred embodiment of the present invention.
FIG. 5 is a cross-sectional view of an angled fenestration providing directional flow in accordance with an alternative embodiment of the present invention. 40 FIG. 6 is a cross-sectional view of an fenestration having check valve characteristics for providing directional flow in accordance with an yet another alternative embodiment of the present invention.
FIG. 7 is a block diagram illustrating the function of a standard lathe in accordance with the prior art.
FIG. 8 is a block diagram illustrating the function of a mill lathe in accordance with an exemplary embodiment of the present invention. 50 FIG. 9 is a diagram illustrating the process by which a multi-step parabolic surface may be created in accordance with another exemplary embodiment of the present invention.
FIG. 10 is a cross-sectional view illustrating rounded and 55 sharp lens edges in accordance with exemplary embodiments of the present invention.
FIG. 11 is a frontal view of a lens having a square-wave indentation pattern in accordance with an exemplary embodiment of the present invention. 60 FIG. 12 is a diagram illustrating a photo-etching process for producing surface features on a lens in accordance with an exemplary embodiment of the present invention.
DETAILED DESCRIPTION OF THE 65 PREFERRED EMBODIMENT
Referring now in more detail to the drawings, the invention will now be described in detail. As shown in FIG. 1, a