IPC분류정보
국가/구분 |
United States(US) Patent
등록
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국제특허분류(IPC7판) |
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출원번호 |
US-0447667
(2003-05-28)
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발명자
/ 주소 |
- Gross, Erik
- Yee, Kingman
- Wong, Jonathan
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출원인 / 주소 |
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대리인 / 주소 |
Townsend and Townsend &
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인용정보 |
피인용 횟수 :
6 인용 특허 :
16 |
초록
The present invention provides systems and methods for applying pulsed energy to an eye. In an exemplary embodiment, a firing rate of the pulsed energy varies in correlation with a modeled or estimated thermal response of a tissue of the eye to the pulses of the laser beam during the treatment.
대표청구항
▼
1. A method for use in planning a corneal refractive procedure, the procedure comprising directing a pattern of ablative laser energy pulses toward a cornea, the method comprising:determining a safe laser firing repetition rate based on a temperature change limit for the cornea and a relationship be
1. A method for use in planning a corneal refractive procedure, the procedure comprising directing a pattern of ablative laser energy pulses toward a cornea, the method comprising:determining a safe laser firing repetition rate based on a temperature change limit for the cornea and a relationship between a pulse characteristic and a rise in temperature of the cornea, the pulse characteristic varying according to the pattern. 2. The method of claim 1, wherein the temperature change limit is less than about 12° C.3. The method of claim 1, wherein the relationship comprises a correlation between change in temperature and at least one of repetition rate and size of the laser beam spot incident on the cornea.4. The method of claim 3, wherein the relationship indicates a substantially linear relationship between change in the repetition rate and the change in temperature for a given spot size.5. The method of claim 3, wherein the pulse characteristic comprises the spot size of the laser beam, the relationship indicating a decrease in spot size corresponds with an increase in repetition rate when producing the change in temperature.6. The method of claim 1, wherein the relationship indicates that a change in temperature ΔT for a spot size having a radius r and repetition rate rep_rate is:ΔT=(0.0533r2+0.407r)rep?rate. 7. The method of claim 1, further comprising determining a plurality of differing pulse repetition rates defining differing time delays between delivery of sequential pulses of the pattern.8. The method of claim 7, wherein at least one of the pulse repetition rates comprises an effective pulse repetition rate at a first location over a time period encompassing multiple pulses, the time period being significantly less than a steady-state temperature time, wherein the pulse characteristic comprises locations of the pulses across the cornea, and wherein the effective pulse repetition rate reflects scanning of the laser between the associated first portion of corneal tissue and a second associated portion of corneal tissue during the time period so that the effective pulse repetition rate at the first location over the time period is less than a total firing rate of the laser.9. The method of claim 7, wherein the temperature change limit comprises an acceptable change in temperature of corneal tissue between a first temperature of the tissue and a maximum desired temperature.10. The method of claim 9, wherein the first temperature comprises an initial equilibrium temperature of the cornea prior to initiation of the procedure.11. The method of claim 10, wherein the first temperature is in a range from about 30 to about 35° C.12. The method of claim 11, wherein the first temperature is about 33° C.13. The method of claim 10, wherein the first temperature is a measured or estimated temperature of corneal tissue.14. The method of claim 9, wherein the maximum desired temperature is selected to be less than a hyperthermia temperature of the corneal tissue.15. The method of claim 9, wherein the maximum desired temperature is less than about 47° C.16. The method of claim 9, wherein the maximum desired temperature is less than about 44° C.17. The method of claim 9, wherein the maximum desired temperature is selected based at least in part on a period of time for which corneal tissue will be heated.18. A method for planning a laser refractive procedure, the procedure comprising directing a pattern of ablative laser energy pulses toward a cornea of the eye, the method comprising:inputting the pattern in a first order so as to define a first pattern; deriving a second pattern from the first pattern based on a corneal heating model by at least one of: i) selectively determining a plurality of differing time delays between sequential pulses, and ii) reordering the pulses of the first pattern; and outputting the second pattern to a laser system for ablating the cornea with the ablative laser energy according to the pattern. 19. The method of claim 18, wherein the time delays are determined by identifying at least one initial thermally safe laser firing repetition rate for the pulses, iteratively reducing the time delays between pulses, and verifying that corneal thermal response remains safe with the reduced time delays.20. The method of claim 19, wherein the at least one initial repetition rate would result in a safe steady-state corneal tissue temperature if the associated pulses were repeated indefinitely.21. The method of claim 20, each pulse of the pattern having an associated laser spot size, the spot sizes of the pulses varying according to the pattern, wherein a series of initial thermally safe laser firing repetition rates are identified in response to the spot sizes.22. The method of claim 19, wherein the corneal thermal response of at least some of the pulses are verified by integrating a plurality of prior pulses within a time window with laser spots encompassing a first location.23. The method of claim 22, wherein the first location is a central pupil location, and wherein the corneal thermal response of the at least some pulses are also verified at a plurality of outlying locations within a treatment region.24. The method of claim 22, wherein the pulses within the time window at the first location have different associated spot sizes, wherein the different spot sizes have associated allowable steady state time delays, and wherein the thermal response of the cornea within the time window is verified by combining the allowable time delays for the pulses of different spot sizes to a total time and comparing the total time to the time window.25. The method of claim 22, wherein the pulses within the time window are scanned across the cornea, wherein the first location is outside at least some of the laser spots of the scanned pulses, and wherein the thermal response is verified using an average pulse rate corresponding to the number of pulses having laser spots encompassing the first location during the time window.26. The method of claim 18, the pattern comprising a series of laser spot locations across the cornea, wherein the first pattern is assigned a first order, and wherein the deriving step comprises reordering the pattern from the first order to a second order, the pattern of pulses in the second order generating a lower estimated cornea temperature than the pattern in the first order or a lower cornea treatment time than the pattern in the first order.27. The method of claim 26, wherein the input pattern in the first order defines a first treatment table, wherein the modified pattern in the second order defines a second treatment table, and wherein the laser spot locations and the associated numbers of laser pulses of the first table are the same for the first and second treatment tables.28. A system for use in planning a corneal refractive procedure, the procedure comprising directing a pattern of ablative laser energy pulses toward a cornea to remove corneal tissue, the system comprising:a tangible media embodying machine readable data including the pattern of a tissue-removing ablative laser energy; a module having at least one input coupled to the tangible media so as to accept the pattern of tissue-removing ablative laser energy, the pattern including a variable pulse characteristic, the module defining a plurality of differing time delays between sequential pulses of the pattern based on: a temperature limit for the cornea; and a relationship between the pulse characteristic and a rise in temperature of the cornea. 29. A system for planning a laser refractive procedure, the procedure comprising directing a pattern of ablative laser energy pulses toward a cornea of the eye so as to remove corneal tissue, the system comprising:a memory containing the pattern of tissue-removing ablative laser energy as machine readable data; a corneal heating model; a module assigning a plurality of differing time delays between sequential pulses of the pattern based on the corneal heating model; and an output for communicating the time delays for ablation of the cornea. 30. A system for planning a laser refractive procedure, the procedure comprising directing a pattern of ablative laser energy pulses toward a cornea of the eye so as to remove corneal tissue, the system comprising:a memory for containing, as machine readable data, the pattern of tissue-removing laser energy in a first order so as to define a first pattern; a corneal heating model coupled to the memory; a module that derives a second pattern from the first pattern by reordering the pulses of the first pattern based on the corneal heating model.
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