Methods for Employing Intrastromal Corrections in Combination with Surface Refractive Surgery to Correct Myopic/Hyperopic Presbyopia
A system and method for correcting a vision defect (i.e. presbyopia) of a patient requires two laser units. A first laser unit is used to photoablate (i.e. remove) tissue from the cornea for the creation of a multi-focal cornea that simultaneously provides for both near and distance vision capabilities. A second laser unit can also be used to refine the shape of the cornea by weakening selected portions with LIOB. Together, the removal and weakening of corneal tissue are regulated to optimize the resultant near vision and distant vision capabilities of the patient.
1 . A method for correcting a vision defect of a patient which comprises the steps of:
removing tissue from the cornea of an eye to create a multi-focal refractive correction, wherein the eye defines a visual axis and the multi-focal refractive correction includes a first correction centered on the visual axis and extending therefrom to correct near vision of the patient, and a second correction surrounding the first correction with an interface region therebetween, with the second correction extending from the first correction to correct distant vision of the patient; and
weakening tissue in the stroma of the eye to balance the first correction with the second correction to optimize the multi-focal correction.
2 . A method as recited in claim 1 wherein the removing step is accomplished by photoablation of the corneal tissue.
3 . A method as recited in claim 2 wherein the removing step is accomplished using a surgical procedure selected from the group consisting of LASIK and PRK.
4 . A method as recited in claim 1 wherein the weakening step is accomplished by Laser Induced Optical Breakdown (LIOB).
5 . A method as recited in claim 4 wherein the weakening step alters the first correction and the second correction of the multi-focal correction.
6 . A method as recited in claim 1 wherein the removing step is accomplished using an excimer laser.
7 . A method as recited in claim 1 wherein the weakening step is accomplished using a pulsed femtosecond laser beam.
8 . A method as recited in claim 1 wherein the vision defect is presbyopia.
9 . A method as recited in claim 8 wherein the vision defect includes at least one additional vision defect.
10 . A method as recited in claim 9 wherein the additional vision defect is selected from a group consisting of myopia, hyperopia and astigmatism.
11 . A method as recited in claim 1 wherein the removing step is accomplished before the weakening step, with a predetermined time interval therebetween.
12 . A method as recited in claim 11 wherein the predetermined time interval is greater than approximately two weeks.
13 . A method as recited in claim 1 wherein the removing step and the weakening step are accomplished substantially simultaneously.
14 . A method for combining corneal tissue removal with an intrastromal redistribution of biomechanical stresses to achieve a predetermined refractive correction for an eye, the method comprising the steps of:
ablating selected corneal tissue in the eye;
performing Laser Induced Optical Breakdown (LIOB) on selected stromal tissue in the eye; and
regulating the ablating step with the performing step to balance a near vision requirement with a distant vision requirement during achievement of the predetermined refractive correction of the eye.
15 . A method as recited in claim 14 wherein the ablating step is accomplished using an excimer laser and the performing step is accomplished using a pulsed femtosecond laser beam.
16 . A method as recited in claim 14 wherein the eye defines a visual axis, and wherein the ablating step, the performing step and the regulating step, in combination, create a multi-focal correction including a first correction centered on the visual axis and extending therefrom to correct near vision of the patient, and a second correction surrounding the first correction with an interface region therebetween, with the second correction extending from the first correction to correct distant vision of the patient.
17 . A method as recited in claim 14 wherein the vision defect is presbyopia.
18 . A method as recited in claim 14 wherein the ablating step is accomplished before the performing step, with a predetermined time interval therebetween.
19 . A method as recited in claim 18 wherein the predetermined time interval is greater than approximately two weeks.
20 . A system for correcting a vision defect of a patient which comprises:
a first laser unit for removing tissue from the cornea of an eye to create a multi-focal refractive correction, wherein the eye defines a visual axis and the multi-focal refractive correction includes a first correction centered on the visual axis and extending therefrom to correct near vision of the patient, and a second correction surrounding the first correction with an interface region therebetween, with the second correction extending from the first correction to correct distant vision of the patient; and
a second laser unit for weakening tissue in the stroma of the eye to balance the first correction with the second correction to optimize the multi-focal correction.