Claims
- 1. A method of corneal sculpting, comprising:directing a beam of infrared laser light having a wavelength of between 1.9 and 5.0 microns onto corneal tissue; supplying the beam in the form of pulses, each of which: (a) has a peak energy density above the ablation threshold for the corneal tissue but whose energy density is sufficiently low to limit the ablation rate to no more than about 3 microns per pulse; (b) has a pulse duration whose full width half maximum (FWHM) is greater than about 300 nsec and is less than the thermal relaxation time of untreated corneal tissue; and (c) has a rise time and a fall time which are both less than 10 microseconds; and ablating a surface of the corneal tissue using the laser light, whereby no substantial tissue damage occurs more than 30 microns below the ablated surface.
- 2. The method of claim 1, wherein the FWHM is less than 50 microseconds.
- 3. The method of claim 1, wherein the laser light includes emission from an erbium ion.
- 4. The method of claim 3, wherein the emission corresponds to the I11/2→I13/2 transition in erbium.
- 5. The method of claim 4, wherein no substantial tissue damage occurs more than 20 microns below the ablated surface.
- 6. The method of claim 4, wherein no substantial tissue damage occurs more than 5 microns below the ablated surface.
- 7. The method of claim 4, wherein the pulse duration of the laser pulses is between about 1 and about 20 microseconds.
- 8. The method of claim 4, wherein the tissue damage is reversible.
- 9. The method of claim 4, wherein the laser pulses have a power density in the range of 0.6-1.5 J/cm2.
- 10. The method of claim 4, further comprising supplying a thin film of water to the corneal tissue to reduce thermal damage to the corneal tissue.
- 11. The method of claim 4, providing pump pulses to produce the laser pulses, the pump pulses having an intensity and duration such that each of the pump pulses produces a respective laser output pulse comprising a dominant spike that contains a significant majority of the laser output pulse energy generated by its respective pump pulse, and wherein each of the respective laser output pulses is separated from an adjacent laser output pulse by a time substantially equal to the time between pump pulses.
- 12. The method of claim 4, wherein the erbium resides in a solid state host.
- 13. The method of claim 4, wherein no substantial tissue damage occurs more than 10 microns below the ablated surface.
- 14. The method of claim 13, wherein the pulse duration of the laser pulses is between about 0.3 and about 1 microsecond.
Parent Case Info
This is a Divisional of application Ser. No. 09/360,588, filed Jul. 26, 1999, now U.S. Pat. No. 6,449,294.
US Referenced Citations (9)
Non-Patent Literature Citations (3)
Entry |
Vogler, K. et al., “Improved Erbium Laser Parameters for New Medical Applications”, Biophotonics International, Nov./Dec. 1996, pp. 40-47. |
Coherent Brochure, “VersaPulse Select Erbium For Vitreoretinal Surgery”, 1994, two pages. |
Zeck et al., “Scanning ablation of dental hard tissue with Erbium laser radiation”, SPIE, vol. 2623, 1994, pp. 94-102. |