Monitoring of retinal temperature during laser therapy

• US 7,465,299 B2
• Filed: 07/14/2005
• Issued: 12/16/2008
• Est. Priority Date: 07/14/2004
• Status: Expired due to Fees

• Current Assignee: Giovanni Staurenghi, Luigi Rovati
• Original Assignee: Giovanni Staurenghi, Luigi Rovati
• Inventors: Rovati, Luigi, Staurenghi, Giovanni
• Primary Examiner(s): Farah; Ahmed M
• Application Number:
  US11/181,524
• Publication Number:
  US 20060084948A1
• Time in Patent Office: 1,251 Days
• Field of Search: 606 4- 6, 606 10- 12, 351205-219, 128/898
• US Class Current: 606/4
• CPC Class Codes: A61B 2017/00057 Light
• CPC Class Codes: A61B 2017/00084 Temperature
• CPC Class Codes: A61F 2009/00844 Feedback systems
• CPC Class Codes: A61F 2009/00857 considering biodynamics
• CPC Class Codes: A61F 2009/00863 Retina
• CPC Class Codes: A61F 2009/00878 Planning
• CPC Class Codes: A61F 9/008 using laser
• CPC Class Codes: A61F 9/00821 for coagulation

Abstract

In a laser eye treatment apparatus, a probe light source generates a secondary emitted light emanating from a treatment area of retinal tissue that is irradiated by a treatment light source. An optical detector detects the secondary emitted light. A processor statistically analyzes the secondary emitted light to determine a temperature of the treatment area of retinal tissue.

Claims

1. A method for measuring retinal temperature, the method comprising:

generating secondary emitted light emanating from retinal tissue;

detecting the secondary emitted light emanating from the retinal tissue;

statistically analyzing temporal fluctuation of the detected secondary emitted light using a control unit including electronics configured for determining a statistical scattering characteristic of the secondary emitted light, the statistical scattering characteristic modeling substantially Brownian motion of illuminated particles of the retinal tissue, and to derive a temperature of the retinal tissue from the statistical scattering characteristic modeling substantially Brownian motion of illuminated particles of the retinal tissue.

2. The method as set forth in claim 1, wherein the statistical analyzing and deriving of a temperature of the retinal tissue from the statistical scattering characteristic comprises:

computing a parameter k_D modeling substantially Brownian motion of illuminated particles of the retinal tissue, the retinal temperature being derived from the parameter k_D.

3. The method as set forth in claim 2, wherein the computing of the parameter k_D comprises:

determining an autocorrelation of the secondary emitted light; and

fitting the autocorrelation with a model having parametric dependence upon the parameter k_D of the retinal tissue.

4. The method as set forth in claim 2, wherein the deriving of the retinal temperature comprises:

determining a relationship between the retinal temperature and the parameter k_D.

5. The method as set forth in claim 4, wherein the relationship between the retinal temperature and the parameter k_D is a linear relationship.

6. The method as set forth in claim 1, wherein the determining of a statistical scattering characteristic comprises:

determining an autocorrelation of the secondary emitted light, the statistical scattering characteristic modeling substantially Brownian motion of illuminated particles of the retinal tissue being derived from the autocorrelation.

7. The method as set forth in claim 6, wherein the deriving of the retinal temperature from the statistical scattering characteristic comprises:

deriving the retinal temperature based on a linear relationship between the statistical scattering characteristic modeling substantially Brownian motion of illuminated particles of the retinal tissue and the retinal temperature.

8. A laser eye treatment method comprising:

applying a treatment laser to a treatment area of retinal tissue;

generating secondary emitted light emanating from the treatment area of retinal tissue;

detecting the secondary emitted light; and

processing the detected secondary emitted light using a control system including electronics configured to perform method operations including determining a statistical scattering characteristic of the secondary emitted light computing a parameter k_D of molecules of the treatment area of retinal tissue from the statistical scattering characteristic, and deriving a retinal temperature from the parameter k_D.

9. The laser eye treatment method as set forth in claim 8, wherein the determining of a statistical scattering characteristic comprises:

determining an autocorrelation of the secondary emitted light.

10. The laser eye treatment method as set forth in claim 9, wherein the computing of a parameter k_D comprises:

fitting the autocorrelation with a model having parametric dependence upon the parameter k_D of the retinal tissue.

11. The laser eye treatment method as set forth in claim 9, wherein the deriving of a retinal temperature from the parameter k_D comprises:

determining a constant of proportionality between the retinal temperature and the parameter k_D.

12. The laser eye treatment method as set forth in claim 11, wherein the determining of a constant of proportionality comprises:

performing the generating of secondary emitted light, the determining of a statistical scattering characteristic, and the computing a parameter k_D at normal body temperature;

deriving the constant of proportionality based on (i) the parameter k_D at normal body temperature and (ii) the normal body temperature.

13. The laser eye treatment method as set forth in claim 9, wherein the deriving of a retinal temperature from the parameter k_D comprises:

determining an intercept of a linear relation between the retinal temperature and the parameter k_D.

14. The A laser eye treatment apparatus comprising:

a continuous wave probe light source for generating secondary light emanating from a treatment area of retinal tissue that is irradiated by a treatment light source;

an optical detector for detecting the secondary light and

a processor for statistically analyzing the secondary light to determine a temperature of the treatment area of retinal tissue, the processor including a correlator that generates an autocorrelation of the output of the optical detector.

15. The laser eye treatment apparatus as set forth in claim 14, further comprising:

a treatment light source for generating lesions in the treatment area of retinal tissue.

16. The laser eye treatment apparatus as set forth in claim 14, wherein the continuous wave probe light source for generating secondary emitted light also functions as a treatment light source for generating lesions in the treatment area of retinal tissue.

17. The laser eye treatment apparatus as set forth in claim 14, wherein the processor further comprises:

an optimizer that optimizes the autocorrelation output by the correlator with respect to a parameter k_D; and

a converter that converts the parameter k_D into a retinal temperature.

18. The laser eye treatment apparatus as set forth in claim 14, wherein the continuous wave probe light source is selected from a group consisting of a light emitting diode (LED) or a laser.