Methods and apparatus for presbyopia correction using ultraviolet and infrared lasers

Abstract

Presbyopia is treated by a system using various lasers to remove a portion of the scleral tissue and increase the accommodation of the presbyopic patient's eye. Stable accommodation is achieved by the filling of the sub-conjunctiva tissue to the laser-ablated scleral areas. The proposed laser wavelength ranges from ultraviolet to infrared of (0.15-0.36) microns, (0.5-1.4) microns and (0.9-3.2) microns. Both scanning and fiber delivered systems are proposed to generate the ablation patterns. Laser ablation of the sclera may be conducted with or without opening the conjunctiva layer.

Description

[0001] This is a Continuation-in-part of application Ser. No. 09 / 303,673 filed on May 3, 1999.[0002] 1. Field of the Invention[0003] The present invention relates to apparatus and methods for the treatment of presbyopia using ultraviolet and infrared lasers to ablate the sclera tissue of an eye.[0004] 2. Prior Art[0005] Corneal reshaping, including a procedure called photorefractive keratectomy (PRK) and a new procedure called laser assisted in situ keratomileusis, or laser intrastroma keratomileusis (LASIK), has been performed by lasers in the ultraviolet (UV) wavelength of 193-213 nm. Commercial UV refractive lasers include ArF excimer lasers at 193 nm and other non-excimer, solid-state lasers, such as the one patented by the present inventor in 1992 (U.S. Pat. No. 5,144,630). Precise, stable corneal reshaping requires lasers with strong tissue absorption (or minimum penetration depth) such that the thermal damage zone is at a minimum (less than few microns). Furthermore, accuracy...

AI Technical Summary

Benefits of technology

[0015] It is yet another objective of the present invention to use a scanning device such that the degree of ciliary mussel accommodation can be controlled by the location, size and shapes of the removed sclera tissue.

Problems solved by technology

The above-described prior arts are however limited to the use of reshaping the corneal surface curvature for the correction of myopia, astigmatism and hyperopia.

Presbyopic problem is not due to the cornea curvature but comes about as the lens loses its ability to accommodate or focus for near vision as a result of loss of elasticity that is inevitable as people age.

Therefore the existing lasers using corneal reshaping can not provide the solution for presbyopia patients.

These mechanical approaches have the drawbacks of complexity and are time consuming, costly and have potential side effects.

However, these prior arts do not present any details or practical methods or laser parameters for the presbyopic corrections.

No clinical studies have been practiced to show the effectiveness of the proposed concepts.

The concepts proposed in the Schachar patents regarding lasers suitable for ablating the sclera tissues were incorrect because many of his proposed lasers are thermal lasers which will cause thermal burning of the cornea, rather than tissue ablation.

Furthermore, the clinical issues, such as locations, patterns and depth of the sclera tissue removal were not indicated in these prior patents.

In addition, Schachar's methods also require the weakening of the sclera and increase the lens diameter by band expansion, which is different from the theory proposed in the present patent, where the sclera tissue becomes more flexible than weakening after laser ablation.

This method, however, involves a lot of bleeding and is difficult to control the depth of the cut which requires extensive surgeon's skill.

Another major drawback for presbyopia correction provided by the above-described non-laser methods is the post-operative regression of about (30%-80%) caused by the healing of the "incision" gap.

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