System and method for refractive surgery with augmentation by intrastromal corrective procedure
View Patent ↗A system and method are provided for an ophthalmic surgical procedure to provide a refractive correction for an eye. Specifically, the procedure is indicated when the desired refractive correction “d reqd ” exceeds the capability of a correction achievable when corneal tissue is only ablated. In accordance with the present invention, an optimized refractive correction “d 1 ” is accomplished by the ablation of corneal tissue (e.g. by a PRK or LASIK procedure). The optimized correction is then followed by a complementary refractive correction “d 2 ” wherein stromal tissue is weakened with Laser Induced Optical Breakdown (LIOB). Together, the optimized refractive correction (ablation) and the complementary refractive correction (LIOB) equal the desire refractive correction (d reqd =d 1 +d 2 ).
1. 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 a predetermined volume of corneal tissue to attain an optimized refractive correction for the eye (d 1 ); and
weakening stromal tissue, by making incisions within the stromal layer below the ablated volume, to incorporate a complementary refractive correction for the eye (d 2 ) along with the optimized refractive correction, to achieve a required refractive correction (d reqd ), wherein the optimized refractive correction is less than the required refractive correction (d 1 <d reqd ).
2. A method as recited in claim 1 wherein d reqd is more than about 3 diopters.
3. A method as recited in claim 2 wherein d 2 is approximately in a range of two to two and one half diopters.
4. A method as recited in claim 1 wherein the ablating step is accomplished prior to the weakening step.
5. A method as recited in claim 1 wherein the ablating step is accomplished as a PRK procedure.
6. A method as recited in claim 1 wherein the ablating step is accomplished as a LASIK procedure.
7. A method as recited in claim 1 wherein the weakening step is accomplished using a femtosecond laser for causing Laser Induced Optical Breakdown (LIOB) of stromal tissue.
8. A method as recited in claim 1 wherein the ablating step is accomplished using an excimer laser.
9. 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:
establishing a required diopter correction for the eye “d reqd ” to achieve the predetermined refractive correction;
determining a first maximum diopter correction for the eye “d 1max ”, wherein d 1max is achievable by removing corneal tissue from the eye, and wherein d reqd is greater than d 1max ;
ascertaining a second maximum diopter correction for the eye “d 2max ”, wherein d 2max is achievable by changing a biomechanical stress distribution in the stroma of the eye, and wherein d reqd is greater than d 2max ;
ablating corneal tissue to achieve a first actual diopter correction “d 1actual ”, wherein d 1actual is less than d 1max ; and
performing Laser Induced Optical Breakdown (LIOB), within the stromal layer below the ablated tissue to achieve a second actual diopter correction “d 2actual ”, wherein d 2actual is less than d 2max , and further wherein d 1actual +d 2actual equals d reqd (d reqd =d 1actual +d 2actual ).
10. A method as recited in claim 9 wherein d reqd is more than about 3 diopters.
11. A method as recited in claim 10 wherein d 2max is approximately in a range of two to two and one half diopters.
12. A method as recited in claim 9 wherein the ablating step is accomplished prior to the performing step.
13. A method as recited in claim 9 wherein the ablating step is accomplished as a PRK procedure.
14. A method as recited in claim 9 wherein the ablating step is accomplished as a LASIK procedure.
15. A method as recited in claim 9 wherein the performing step is accomplished using a femtosecond laser for causing Laser Induced Optical Breakdown (LIOB) of stromal tissue.
16. A method as recited in claim 9 wherein the ablating step is accomplished using an excimer laser.
17. A method as recited in claim 9 wherein the ablating step is accomplished prior to the performing step and is separated therefrom by a time interval of approximately three weeks.