Thermokeratoplasty system with a power supply that can determine a wet or dry cornea

• US 6,986,770 B2
• Filed: 10/07/2003
• Issued: 01/17/2006
• Est. Priority Date: 08/23/1993
• Status: Expired due to Fees

• Current Assignee: Refractec, Inc. (Refractec LLC)
• Original Assignee: Refractec, Inc. (Refractec LLC)
• Inventors: Hood, Larry L.
• Primary Examiner(s): GIBSON, ROY DEAN
• Application Number:
  US10/681,351
• Publication Number:
  US 20040106919A1
• Time in Patent Office: 833 Days
• Field of Search: 606/41, 606 43- 50, 606 28- 32, 606/34, 606/37, 606/39, 606/40
• US Class Current: 606/41
• CPC Class Codes: A61B 18/1206 Generators therefor
• CPC Class Codes: A61B 18/14 Probes or electrodes therefor
• CPC Class Codes: A61B 18/1477 Needle-like probes
• CPC Class Codes: A61B 18/1815 using microwaves
• CPC Class Codes: A61B 2018/00178 Electrical connectors
• CPC Class Codes: A61B 2018/00642 with feedback, i.e. closed loop control
• CPC Class Codes: A61B 2018/00761 Duration
• CPC Class Codes: A61B 2018/00875 Resistance or impedance
• CPC Class Codes: A61B 2018/00886 Duration
• CPC Class Codes: A61B 2018/00988 Means for storing information, e.g. calibration constants, or for preventing excessive use, e.g. usage, service life counter
• CPC Class Codes: A61B 2018/143 multiple needles
• CPC Class Codes: A61B 2018/1475 Electrodes retractable in or deployable from a housing
• CPC Class Codes: A61B 2090/036 abutting on tissue or skin
• CPC Class Codes: A61B 3/10 Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/0538 invasively, e.g. using a catheter
• CPC Class Codes: A61F 2009/00844 Feedback systems
• CPC Class Codes: A61F 2009/00853 Laser thermal keratoplasty or radial keratotomy
• CPC Class Codes: A61F 2009/00865 Sclera
• CPC Class Codes: A61F 2009/00872 Cornea
• CPC Class Codes: A61F 9/0079 : using non-laser electromagnetic radiation, e.g. non-coherent light or microwaves
• CPC Class Codes: A61F 9/008 : using laser
• CPC Class Codes: A61F 9/0133 : Knives or scalpels specially adapted therefor

Abstract

A power supply for a thermokeratoplasty system. The power supply can be connected to an electrode and a return element that are both coupled to a cornea. The power supply can perform a test routine to determine whether the cornea is too “wet” or too “dry”.

Claims

1. An electrical power supply for a thermokeratoplasty tip that can provide an indication of an electrical characteristic of a cornea, comprising:

an electrode pin;

a return pin; and

,

a circuit that can provide a current to said electrode pin and the cornea, and an indication of the electrical characteristic of the cornea in response to the current flowing through the cornea and said electrode and return pins, said circuit varies an amplitude of said current in accordance with the electrical characteristic.

2. The power supply of claim 1, wherein the electrical characteristic is a function of a voltage at said return pin.

3. The power supply of claim 2, wherein the electrical characteristic is a time rate of change of the voltage at said return pin.

4. The power supply of claim 1, wherein said circuit provides a series of radio frequency test pulses to said electrode pin.

5. The power supply of claim 4, wherein a number of radio frequency test pulses is less than a number of radio frequency operating pulses applied to the cornea.

6. The power supply of claim 1, wherein said circuit provides a wet indicator output signal if the electrical characteristic is equal to or less than a lower threshold value and provides a dry indicator output signal if the electrical characteristic is equal to or greater than an upper threshold value.

7. The power supply of claim 1, wherein said circuit provides a series of operating radio frequency pulses if the electrical characteristic is greater than a lower threshold and less than an upper threshold.

8. A method for testing an electrical contact between a thermokeratoplasty electrode, a cornea and a return element, comprising:

transmitting a current through the electrode, the cornea and the return element;

comparing an electrical characteristic of the cornea to a threshold value; and

,

generating an indicator output signal if the electrical characteristic is equal to or is greater than an absolute value of the threshold value.

9. The method of claim 8, providing a series of radio frequency operating pulses if the electrical characteristic is less than the absolute value of the threshold value.

10. The method of claim 9, varying an amplitude of the radio frequency operating pulses in accordance with the electrical characteristic.

11. The method of claim 8, wherein the electrical characteristic is a time rate of change of a voltage of a return pin.

12. The method of claim 8, wherein a wet indicator output signal is generated if the voltage characteristic is equal to or less than a lower threshold value, and a dry indicator output signal is generated if the electrical characteristic is equal to or greater than a upper threshold value.

13. An electrical power supply for a thermokeratoplasty tip that can provide an indication of an electrical characteristic of a cornea, comprising:

an electrode pin;

a return pin; and

,

a circuit that can provide a current to said electrode pin and the cornea, and an indication of the electrical characteristic of the cornea in response to the current flowing through the cornea and said electrode and return pins, said circuit provides a series of radio frequency test pulses to said electrode pin.

14. The power supply of claim 13, wherein the electrical characteristic is a function of a voltage at said return pin.

15. The power supply of claim 14, wherein the electrical characteristic is a time rate of change of the voltage at said return pin.

16. The power supply of claim 13, wherein a number of radio frequency test pulses is less than a number of radio frequency operating pulses applied to the cornea.

17. The power supply of claim 13, wherein said circuit provides a wet indicator output signal if the electrical characteristic is equal to or less than a lower threshold value and provides a dry indicator output signal if the electrical characteristic is equal to or greater than an upper threshold value.

18. The power supply of claim 13, wherein said circuit provides a series of operating radio frequency pulses if the electrical characteristic is greater than the lower threshold and less than the upper threshold.

19. An electrical power supply for a thermokeratoplasty tip that can provide an indication of an electrical characteristic of a cornea, comprising:

an electrode pin;

a return pin; and

,

a circuit that can provide a current to said electrode pin and the cornea, and an indication of the electrical characteristic of the cornea in response to the current flowing through the cornea and said electrode and return pins, said circuit provides a wet indicator output signal if the electrical characteristic is equal to or less than a lower threshold value and provides a dry indicator output signal if the electrical characteristic is equal to or greater than an upper threshold value.

20. The power supply of claim 19, wherein the electrical characteristic is a function of a voltage at said return pin.

21. The power supply of claim 20, wherein the electrical characteristic is a time rate of change of the voltage at said return pin.

22. The power supply of claim 19, wherein said circuit provides a series of operating radio frequency pulses if the electrical characteristic is greater than the lower threshold and less than the upper threshold.

23. An electrical power supply for a thermokeratoplasty tip that can provide an indication of an electrical characteristic of a cornea, comprising:

an electrode pin;

a return pin; and

,

a circuit that can provide a current to said electrode pin and the cornea, and an indication of the electrical characteristic of the cornea in response to the current flowing through the cornea and said electrode and return pins said circuit provides a series of operating radio frequency pulses if the electrical characteristic is greater than a lower threshold and less than an upper threshold.

24. The power supply of claim 23, wherein the electrical characteristic is a function of a voltage at said return pin.

25. The power supply of claim 24, wherein the electrical characteristic is a time rate of change of the voltage at said return pin.