Surgery – Instruments – Light application
Reexamination Certificate
1999-06-02
2001-03-06
Dvorak, Linda C. M. (Department: 3739)
Surgery
Instruments
Light application
C606S013000
Reexamination Certificate
active
06197018
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention is directed generally to the correction of vision and, more specifically to the reversing the effects of aging on accommodation by increasing the tension of the capsular membrane.
The normal aging process is associated with a loss of accommodative potential (presbyopia). This loss of accommodation requires the use of corrective lenses in order to perform visual tasks at near, such as reading.
Moreover, many patients have a hyperopic refractive error for which they compensate by using their accommodative potential when they are young. As they grow older, therefore, they more easily exhaust their accommodative reserve resulting in a biphasic pattern of increased dependence on optical appliances. Initially, they develop a need for corrective lenses just for near work; but eventually, they need corrective lenses for distances as well.
Patients with low to moderate myopia can compensate for presbyopia by removing their corrective lenses for near work. With the introduction of effective means for correcting myopia by photorefractive keratectomy (PRK), these patients forfeit the option when they elect to have their myopia eliminated.
The etiology of presbyopia has not been firmly established. Contributing factors identified to date include an apparent loss of ciliary muscle function, sclerosis of the crystalline lens fibers, loss of capsular tension by reduced elasticity, and crowding of the anterior segment of the eye by continued growth of the crystalline lens after puberty.
Recently, a method of restoring accommodative amplitude by expanding the equatorial circumference of the globe over the ciliary body by a variety of surgical techniques has been disclosed. These surgical techniques are quite invasive requiring deep invasions in the eyeball or the suturing of an expansive band to the eyeball.
SUMMARY OF THE INVENTION
One object of the present invention is to provide a method of performing a non-invasive alteration of the lens capsular membrane tension by the application of laser energy restoring the accommodative potential.
Another object of the invention includes the use of the appropriate laser energy that can be used to restore the accommodative potential of the ocular lens with or without a concomitant change in refractive error through usage of this procedure.
Another object of the invention is to control the laser wave length for providing an adequate transmission to the target plane of the lens capsular membrane by selecting a focal spot size of sufficient size to effect a local contractor of the lens capsular membrane.
Yet another object of the invention is provide a method for placing a symmetrical pattern of spots to avoid induction of lenticular astigmatism, and by accurate placement of the spots away from these pupillary space to avoid optical side effects.
Another object of the invention is to provide for the restoration of accommodative reserve by the use of an infrared laser to cause a tightening of the lens capsular membrane.
Another object of this invention is to provide the method for achieving such restoration, as aforesaid, wherein the laser wave length selected is in the near infrared range of 800 nm to 1900 nm.
Yet another object of this invention is to provide a method wherein the laser is a continuous wave laser delivered in a pulsed fashion for a duration of 0.01 second to 1 second per spot application.
Yet another object of this invention is to provide the method for restoration wherein the laser spot size is selected to be between 100 to 500 microns in diameter.
Still another object of this invention is to provide the method for restoration wherein the laser energy per spot application is in the range of 50 mW to 1,000 mW.
Yet another object of this invention is to provide a method for restoration of the accommodative reserve of the lens wherein the treatment spots are arranged in a symmetrical fashion along a circle or concentric circles of 7 mm to 13 mm in diameter.
Still another object of this invention is to provide a method of restoration of the accommodative reserve of the lens wherein the hyperoptic refractive error is concurrently corrected (myopic shift) by placing the spots closer to the pupil center.
Yet another object of this invention is to provide a method for restoration wherein an astigmatic refractive error is concurrently corrected by placing additional spots closer to the pupil center along the flat meridian.
Yet another object of this invention is to provide the method for restoration wherein the spot intensity is increased along the flat meridian to compensate for unwanted astigmatism.
Another method of this invention is to provide for restoration wherein the laser energy is precisely focused onto the interior or posterior lens capsule.
In accordance with the invention, generally stated, the present invention provides a method of presbyopia correction comprising the tightening or tensioning of the crystalline lens capsule by applying laser energy to the pre-equatorial lens capsular basement membrane, the capsule tension is increased without unwanted effects on the central clarity or on the refractive status of the eye. Wavelength selection, power, pulse duration, treatment spot size, placement, and pattern affect the accommodative and refractive effect.
Other objects and advantages may become more apparent to those skilled in the art upon reviewing this summary of the invention, in view of the description of the preferred embodiment.
REFERENCES:
patent: 6099522 (2000-08-01), Knopp et al.
Denk Paul M.
Dvorak Linda C. M.
Gibson Roy
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