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Simulating corneal laser surgery

Filed on May 13, 1996

An apparatus and method are provided for simulating a predicted post-operative topography of a cornea of an eye based on a pre-operative topography of the cornea and a proposed laser ablation procedure. A digital data processing system receives data defining a pre-operative topography of the cornea as a function of location and obtains parameters of the proposed laser ablation procedure from which the digital data processing system can determine the amount of cornea expected to be ablated as a function of location on the cornea. Based on the data and the parameters, the digital data processing system produces an output representing a simulated post-operative topography of the cornea as a function of location. The parameters of the proposed laser ablation procedure specify variations in a cut rate of the laser beam (such as data specifying a plurality of laser beam cut rates for each of a corresponding plurality of laser beam pulses, or data specifying relative laser beam energy level or fluence at each of a plurality of points within the laser beam).

Claims

1. An apparatus for producing a simulated post-operative topography model simulating a predicted post-operative topography of a cornea of an eye based on a pre-operative topography of said cornea and a proposed laser ablation procedure, comprising:

a digital data processing system configured to receive data defining a pre-operative topography of said cornea as a function of location, to obtain parameters of said proposed laser ablation procedure from which said digital data processing system can determine the amount of cornea expected to be ablated as a function of location on said cornea, and, based on said data and said parameters, to produce a simulated post-operative topography model representing a simulated post-operative topography of said cornea as a function of location; and
a visual display system connected to said digital data processing system for receiving said simulated post-operative topography model from said digital data processing system and for displaying said simulated post-operative topography model of said cornea as a function of location.

2. An apparatus in accordance with claim 1, further comprising a corneal topography measurement system, in communication with said digital data processing system, configured to measure the topography of said cornea as a function of location on said cornea and to produce said data defining said pre-operative topography of said cornea.

3. An apparatus in accordance with claim 1, wherein said digital data processing system comprises means for determining the amount of cornea expected to be ablated as a function of location by internally performing calculations based on said parameters.

4. An apparatus in accordance with claim 1, wherein said digital data processing system comprises means for determining the amount of cornea expected to be ablated as a function of location by receiving from an external processor that operates a laser that performs said laser ablation procedure information pertaining to said amount of cornea expected to be ablated as a function of location.

5. An apparatus in accordance with claim 1, wherein said digital data processing system comprises means for producing said simulated post-operative topography model of said cornea, said means for producing said simulated post-operative topography model comprising means for simulating post-operative elevation of said cornea as a function of location.

6. An apparatus in accordance with claim 5, wherein said digital data processing system comprises means for causing said simulated post-operative elevation of said cornea to be displayed with respect to a best-fit geometric shape.

7. An apparatus in accordance with claim 6, wherein said digital data processing system comprises means for causing said simulated post-operative elevation of said cornea to be displayed with respect to a best-fit geometric shape that comprises a best-fit sphere.

8. An apparatus in accordance with claim 1, wherein said digital data processing system comprises means for causing said simulated post-operative topography model to be displayed in a color-coded manner, where each color represents a certain positive or negative deviation from a geometric baseline.

9. An apparatus in accordance with claim 1, wherein said digital data processing system comprises means for producing said simulated post-operative topography model based on parameters of said proposed laser ablation procedure that comprise a plurality of successive laser beam aperture configurations.

10. An apparatus in accordance with claim 9, wherein said digital data processing system comprises means for producing said simulated post-operative topography model based on parameters of said proposed laser ablation procedure that comprise a number of laser beam pulses to be delivered at each of said laser beam aperture settings.

11. An apparatus in accordance with claim 10, wherein said digital data processing system comprises means for producing said simulated post-operative topography model based on parameters of said proposed laser ablation procedure that comprise a pre-operative radius of curvature of said cornea, and said digital data processing system comprises means for obtaining said number of laser beam pulses to be delivered at each of said laser beam aperture settings by deriving said number from said pre-operative radius of curvature of said cornea.

12. An apparatus in accordance with claim 10, wherein said digital data processing system comprises means for producing said simulated post-operative topography model based on parameters of said proposed laser ablation procedure that comprise a pre-operative refractive correction prescription, and said digital data processing system comprises means for obtaining said number of laser beam pulses to be delivered at each of said laser beam aperture settings by deriving said number from said pre-operative refractive correction prescription.

13. An apparatus in accordance with claim 10, wherein said digital data processing system comprises means for producing said simulated post-operative topography model based on parameters of said proposed laser ablation procedure that comprise a pre-operative optical zone diameter, and said digital data processing system comprises means for obtaining said number of laser beam pulses to be delivered at each of said laser beam aperture settings by deriving said number from said pre-operative optical zone diameter.

14. An apparatus in accordance with claim 10, wherein said digital data processing system comprises means for producing said simulated post-operative topography model based on parameters of said proposed laser ablation procedure that comprise a refraction index of said cornea, and said digital data processing system comprises means for obtaining said number of laser beam pulses to be delivered at each of said laser beam aperture settings by deriving said number from said refraction index of said cornea.

15. An apparatus in accordance with claim 1, wherein said digital data processing system comprises means for producing said simulated post-operative topography model based on parameters of said proposed laser ablation procedure that comprise a laser beam cut rate.

16. An apparatus in accordance with claim 1, wherein said digital data processing system comprises means for producing said simulated post-operative topography model based on parameters of said proposed laser ablation procedure that comprise a plurality of laser beam cut rates for each of a corresponding plurality of laser beam pulses.

17. An apparatus in accordance with claim 1, wherein said digital data processing system comprises means for producing said simulated post-operative topography model based on parameters of said proposed laser ablation procedure that comprise relative laser beam fluence at each of a plurality of points within a laser beam.

18. A method of producing a simulated post-operative topography model simulating a predicted post-operative topography of a cornea based on a pre-operative topography of said cornea and a proposed laser ablation procedure, comprising the steps of:

obtaining from a corneal topography measurement system data defining a pre-operative topography of said cornea as a function of location;
obtaining parameters of said proposed laser ablation procedure;
determining from said parameters the amount of cornea expected to be ablated as a function of location on said cornea; and
calculating, based on said pre-operative topography and said amount of cornea expected to be ablated, a simulated post-operative topography model representing a simulated post-operative topography of said cornea as a function of location.

19. A method in accordance with claim 18, further comprising the step of displaying, on a visual display system, said simulated post-operative topography of said cornea as a function of location.

20. An apparatus for simulating a predicted change in topography of a cornea of an eye based on a proposed laser ablation procedure and based on parameters specifying variations in a cut rate of a laser beam, comprising:

a digital data processing system configured to obtain parameters of said proposed laser ablation procedure from which said digital data processing system can determine the amount of cornea expected to be ablated as a function of location on said cornea, and, based on said parameters, to produce an output representing a simulated change in topography of said cornea as a function of location, said parameters specifying variations in a cut rate of a laser beam that ablates said cornea; and
a visual display system connected to said digital data processing system for receiving said output of said digital data processing system and for displaying said simulated change in topography of said cornea as a function of location.

21. An apparatus in accordance with claim 20, wherein said digital data processing system comprises means for producing said output representing said simulated change in topography based on parameters specifying variations in a cut rate of said laser beam that comprise a plurality of laser beam cut rates for each of a corresponding plurality of laser beam pulses.

22. An apparatus in accordance with claim 20, wherein said digital data processing system comprises means for producing said output representing said simulated change in topography based on parameters specifying variations in a cut rate of said laser beam that comprise relative laser beam fluence at each of a plurality of points within said laser beam.

23. An apparatus in accordance with claim 20, wherein said digital data processing system comprises means for producing said output representing said simulated change in topography of said cornea, said means for producing said output comprising means for simulating post-operative topography of said cornea.

24. A method of simulating a predicted change in topography of a cornea based on a proposed laser ablation procedure and based on parameters specifying variations in a cut rate of a laser beam, comprising the steps of:

obtaining parameters of said proposed laser ablation procedure, said parameters specifying variations in a cut rate of a laser beam that ablates said cornea;
determining from said parameters the amount of cornea expected to be ablated as a function of location on said cornea; and
calculating, based on said amount of cornea expected to be ablated, a simulated change in topography of said cornea as a function of location.

25. A method in accordance with claim 24, further comprising the step of displaying, on a visual display system, said simulated change in topography of said cornea as a function of location.

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Other references

  • Belin, Michael W.; Cambier, James L.; and Nabors, John R.; “PAR Corneal Topography System”; Corneal Topography: The State of the Art; Gills, J. et al., editors; Slack, Inc.; Thorofare, NJ; ch. 8, pp. 105-122; 1995. Belin, Michael W.; Cambier, James L.; Nabors, John R.; and Ratliff, C. Derek; “PAR Corneal Topography System (PAR CTS): The Clinical Application of Close-Range Photogrammetry”; Opt. Vis. Sci.; 72(11): pp. 828-837; 1995. El Hage, Sami G.; Salz, James J.; Belin, Michael W.; Costin, John A.; and Gressel, Michael G.; “Corneal Topography as Measured by the EyeMap EH-270”; Corneal Topography; chapter 4, pages 37-52; 1995. Gottsch, John D.; Rencs, Erik V.; Cambier, James L.; Hall, Deborah; Azar, Dimitri T.; and Stark Walter J.; “Excimer Laser Calibration System”; Journal of Refractive Surgery; vol. 12, pp. 401-411; Mar./Apr. 1996. Munnerlyn, Charles R.; Koons, Stephen J.; and Marshall, John; “Photorefractive Keratectomy: A Technique fo Laser Refractive Surgery”; Journal of Cataract Refractive Surgery; vol. 14, pp. 44-52; Jan., 1988. PAR Vision Systems Corporation; “CTS.TM.Corneal Topography System is More Than Meets the Eye”. Rozakis, George W.; “Lasear Simulation Software: Mastering the Response of the Cornea”; Ocular Surgery News; Jul. 15, 1995; pp. 48-49. Smolek, Michael K. and Klyce, Stephen D.; “The Tomey Technology/Computed Anatomy TMS-1 Videokeratoscope”; Corneal Topography: The State of the Art; Gills, J. et al., Slack, Inc.; ch. 9, pp. 124-149; 1995. Snook, Richard K.; “Pachymetry and True Topography Using the ORCAN System”; Corneal Topography: The State of the Art; Gills, J. et al., editors; Slack, Inc.; Thorofare, NJ; chapter 7, pp. 89-103; 1995. Thornton, Spencer P. and Wakil, Joseph; “The EyeSys 2000 Corneal Analysis System”; Corneal Topography: The State of the Art; Gills, J. et al., editors; Slack, Inc.; Thorofare, NJ; chapter 5, pp. 55-75; 1995. Waring III, George O. et al., “Photorefractive Keratectomy for Myopia Using a 4.5-Millimeter Ablation Zone”; Journal of Refractive Surgery; vol. 11, pp. 170-180; May/Jun. 1995.

Patent History

Patent number: 5843070
Type: Grant 
Filed: May 13, 1996
Date of Patent: Dec 1, 1998
AssigneeParTech, Inc. (New Hartford, NY) 
InventorsJames L. Cambier (Rome, NY), George W. Rozakis (Lakewood, OH) 
Primary ExaminerRobert L. Nasser 
Law FirmFish & Richardson P.C.
Application Number: 8/645,100

Classifications

Current U.S. ClassRecurving Or Reshaping Of The Eye (606/5)Ophthalmic (606/4) 
International Classification: A61M 506; 

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