Refractive surgery and presbyopia correction using infrared and ultraviolet lasers
View Patent ↗A method and surgical technique for corneal reshaping and for presbyopia correction are provided. The preferred embodiments of the system consists of a scanner, a beam spot controller and coupling fibers and the basic laser having a wavelength of (190-310) nm, (0.5-3.2) microns and (5.6-6.2) microns and a pulse duration of about (10-150) nanoseconds, (10-500) microseconds and true continuous wave. New mid-infrared gas lasers are provided for the corneal reshaping procedures. Presbyopia is treated by a method which uses ablative laser to ablate the sclera tissue and increase the accommodation of the ciliary body. The tissue bleeding is prevented by a dual-beam system having ablative and coagulation lasers. The preferred embodiments include short pulse ablative lasers (pulse duration less than 200 microseconds) with wavelength range of (0.15-3.2) microns and the long pulse (longer than 200 microseconds) coagulative lasers at (0.5-10.6) microns. Compact diode lasers of (980-2100) nm and diode-pumped solid state laser at about 2.9 microns for radial ablation patterns on the sclera ciliary body of a cornea are also disclosed for presbyopia correction using the mechanism of sclera expansion.
1. A method of performing refractive surgery by reshaping a portion of corneal tissue, said method comprising the steps of:
selecting a gas laser generated by transverse electrical discharge in a mixture of neural gases including at least helium gas and having a pulsed output beams of predetermined mid-IR wavelength of (2.7-3.2) microns;
selecting a beam spot controller mechanism, said spot controller consisting of an internal magentic coupler integrated inside the laser cavity having a pin-hole size of about (2-10) mm;
focusing the output beam to a spot size of about (0.05-2.5) mm on the corneal surface;
selecting a scanning mechanism for scanning said selected laser output beam;
coupling said laser beam to a scanning device for scanning said laser beam over a predetermined corneal surface area to remove corneal tissue, whereby a patient's vision is corrected by reshaping the cornea.
2. A method of claim 1 , in which the hydration level of said corneal surface area is controlled by a gas blower such that a consistent tissue ablation rate can be achieved.
3. A method for improving presbyopic patient's vision by removing a portion of the sclera tissue from an eye of a patient, said method comprising the steps of accommodation and/or treating presbyopia, the method comprising:
selecting an ablative laser for removing sclera tissue by focusing said ablative laser to a spot size of about (5-800) microns on the corneal surface;
selecting a scanning mechanism for scanning said ablative laser;
coupling said ablative laser to a scanning device for scanning said ablative laser over a predetermined area outside the corneal limbus to remove said sclera tissue;
removing sclera tissue from outside the corneal limbus area, said removing comprising forming a pattern of radial lines in the sclera to a depth of 500 - 600 microns, whereby a patient's near vision is improved by the increase of the corneal lens accommodation.
4. A method of claim 3 , in which said removing is performed using an ablative laser is a gas laser having an output wavelength of about (2.7-3.2) microns, energy per pulse of about (0.5-15) mJ on the corneal surface and a pulse duration less than 150 nanoseconds.
5. A method of claim 3 , in which said ablative laser is a mid-IR solid-state laser having a wavelength of about (2.7-3.2) microns.
6. The method of claim 3 , in which said ablative laser includes removing is performed using pulsed radiation generated by a transverse electrical discharge carbon dioxide laser which is frequency-doubled into a laser having a wavelength of about (5.6-6.2) microns, energy per pulse of about (2-15) mJ on the corneal surface.
7. A method of claim 3 , in which said ablative laser is removing is performed using a diode laser having a wavelength of about 980 nm.
8. A method of claim 3 , in which said ablative laser is removing is performed using a diode laser having a wavelength of about (1.4-2.1) microns.
9. A method of claim 3 , in which said ablative laser is removing is performed using a diode-pumped Er:YAG laser having a wavelength about 2.9 microns and a pulse duration less than 500 microseconds.
10. A method of claim 3 , in which said ablative laser is removing is performed using an ultraviolet laser having wavelength of about (190-310) nm.
11. A method of claim 3 , in which said sclera tissue is coagulated by a laser having a wavelength of about (0.5-3.2) microns, an average power of about (0.1-5.0) W on the corneal surface, spot size of about (0.1-1.0) mm, and a pulse duration longer than about 200 seconds.
12. A method of claim 3 , in which said removing is performed using an ablative laser is fiber-coupled and combined with a coagulation laser and delivered to the corneal eye surface.
13. A method of claim 3 , in which said sclera tissue is ablated in radial patterns having a length about (2.5-3.5) mm and a depth about (400-700) microns .
14. A method of claim 3 , in which said sclera tissue is ablated in radial patterns by a computer-controlled scanning mechanism.
15. A method of claim 3 , in which said sclera tissue is ablated in radial patterns by a translation mechanism.
16. A method as in claim 3 wherein the radial lines are at least 2 . 5 mm in length.
17. A method as in claim 3 wherein the removing is performed using a pulsed laser having a pulse duration of about 10 - 500 microseconds.
18. A method as in claim 3 wherein the removing is performed using a laser focused to a spot size of about 5 - 500 microns.