MEASUREMENT SYSTEM AND METHOD FOR ESTABLISHING THE REFRACTION OF AN EYE, THE RADIUS OF CURVATURE OF THE CORNEA OR THE INTERNAL PRESSURE OF AN EYE

• US 20110202017A1
• Filed: 02/08/2011
• Published: 08/18/2011
• Est. Priority Date: 02/12/2010
• Status: Active Grant

• Current Assignee: Carl Zeiss Meditec AG (Carl-Zeiss-Stiftung)
• Original Assignee: Carl Zeiss Surgical GmbH (Carl-Zeiss-Stiftung)
• Inventors: Reimer, Peter
• Granted Patent: US 10,080,493 B2
• Time in Patent Office: Days
• US Class Current: 604/290
• CPC Class Codes: A61B 3/103 for determining refraction, e.g. refractometers, skiascopes
• CPC Class Codes: A61B 3/107 for determining the shape or measuring the curvature of the cornea
• CPC Class Codes: A61B 3/165 Non-contacting tonometers
• CPC Class Codes: A61F 9/007 Methods or devices for eye surgery

Abstract

A method for establishing the refraction of an eye (9) by means of a refractometer (3) is provided, in which the current visual axis (S) of the eye (9) is established before establishing the refraction, the refractometer (3) is aligned with respect to the visual axis (S) of the eye (9) and the refraction is established after the alignment. The visual axis (S) of the eye (9) is established on the basis of the position of a Purkinje image of at least one light source (41, 50) used to illuminate the eye and a relationship between the position of the Purkinje image and the visual axis (S).

Claims

1. A method for establishing refraction of an eye (9) by means of a refractometer (3), comprising:

establishing the current visual axis (S) of the eye (9) before establishing the refraction;

aligning the refractometer (3) with respect to the visual axis (S) of the eye (9) and establishing the refraction after the alignment, wherein the visual axis (S) of the eye (9) is established on the basis of the position of a Purkinje image of at least one light source (41, 50) used to illuminate the eye and a relationship between the position of the Purkinje image and the visual axis (S).

2. The method of claim 1, in which the relationship between the visual axis (S) and the position of the Purkinje image on the eye (9) is established during a reference measurement.

3. The method of claim 1, in which the relationship between the visual axis (S) and the position of the Purkinje image on the eye is established on the basis of a mathematical model.

4. The method of claim 1, in which establishing the visual axis (S) of the eye is established on the basis of the first Purkinje image of at least one light source (41, 50).

5. The method of claim 1, further comprising establishing a radius of curvature of a cornea (63) and/or internal pressure of an eye (9) by illuminating the eye (9) by at least one light source (41, 50) and establishing the radius of curvature and/or the internal pressure on the basis of a property of at least one Purkinje image of the light source (41, 50) and a relationship between this property and the radius of curvature and/or the internal pressure.

6. A method for establishing a radius of curvature of a cornea (63) and/or internal pressure of an eye (9), comprising illuminating the eye (9) by at least one light source (41, 50) and establishing the radius of curvature and/or the internal pressure on the basis of a property of at least one Purkinje image of the light source (41, 50) and a relationship between this property and the radius of curvature and/or the internal pressure.

7. The method of claim 6, in which the relationship between the property of the at least one Purkinje image and the radius of curvature and/or the internal pressure is established by a reference measurement at a normal radius of curvature and/or normal internal pressure.

8. The method of claim 6, in which the property of the at least one Purkinje image is the size thereof.

9. The method of claim 6, in which there are at least two light sources (41A, 41B) and the property of the Purkinje images is their distance from one another on the cornea (63).

10. The method of claim 6, in which the radius of curvature and/or the internal pressure is established on the basis of a property of at least one first Purkinje image of the light source (41, 50).

11. A method for adjusting the internal pressure of an eye during eye surgery, in which the radius of curvature and/or internal pressure is established according to the method of claim 6, further comprising establishing a deviation of the internal pressure from a target value and bringing the internal pressure to the target value on the basis of the established deviation.

12. The method of claim 11, using a rinsing fluid (65) with an adjustable pressure to bring the internal pressure to the target value.

13. The method of claim 12, in which the light source (41, 50) is an illumination apparatus of a surgical microscope (1).

14. A measurement system for establishing the refraction of an eye (9), comprising:

a refractometer (3) that has an optical axis;

at least one light source (41, 50) for illuminating the eye (9);

an electronic image-recording device (27) for recording an electronic image of the illuminated eye (9);

an image-processing unit (55) connected to the image-recording device (27) to receive the electronic image, the image-processing unit (55) comprising means for determining the position of at least one Purkinje image of the at least one light source (41, 50), on the cornea (63) of the eye (9) on the basis of the received electronic image;

an evaluation unit (57) connected to the image-processing unit (55) to receive the position of the at least one Purkinje image for establishing the visual axis (S) of the eye (9) on the basis of the position of the at least one Purkinje image and a relationship between the position of the at least one Purkinje image and the visual axis (S); and

an adjustment unit (5) connected to the evaluation unit (57) to receive the established visual axis (S) and connected to the refractometer (3) to align the refractometer with respect to the visual axis (S) of the eye.

18. The measurement system of claim 14, which additionally further comprising a medical-optical observation instrument (1) with an illumination device and the at least one light source (41, 50) being a light source of the illumination device.

19. Measurement system according to claim 18, in which the medical-optical observation instrument is equipped with a coaxial illumination apparatus (41A, 41B).

15. A measurement system for establishing the radius of curvature and/or the internal pressure of an eye (9), comprising:

at least one light source (41, 50) for illuminating the eye (9);

an electronic image-recording device (27) for recording an electronic image of the illuminated eye (9);

an image-processing unit (155) connected to the image-recording device (27) to receive the electronic image, the image-processing unit (155) comprising means for determining the position and/or the size of at least one Purkinje image of the at least one light source (41, 50) on the cornea (63) of the eye (9) on the basis of the received electronic image; and

an evaluation device (157), connected to the image-processing unit (155) to receive the position and/or the size of the at least one Purkinje image for establishing the radius of curvature and/or the internal pressure on the basis of the position and/or the size of the at least one Purkinje image and a relationship between the position and/or the size of the at least one Purkinje image and the radius of curvature and/or between the position and/or the size of the at least one Purkinje image and the internal pressure.

16. The measurement system of claim 15, where the at least one light source comprises at least two light sources (41A, 41B) and the image-processing unit (155) comprises means for determining the distance of the Purkinje images of the light sources (41A, 41B) from one another on the cornea (63) and the evaluation device (157) is designed for establishing the radius of curvature and/or the internal pressure on the basis of the distance of the Purkinje images of the light sources (41A, 41B) from one another on the cornea (63) and a relationship between the distance and the radius of curvature and/or between the distance and the internal pressure.

17. The measurement system of claim 15 further comprising a refractometer (3) that has an optical axis, the evaluation unit establishing the visual axis (S) of the eye (9) on the basis of the position of the at least one Purkinje image and a relationship between the position of the at least one Purkinje image and the visual axis (S), and an adjustment unit (5) connected to the refractometer (3) to align the refractometer to the visual axis (S) of the eye, whereby the system further establishes refraction of the eye (9).

20. System for adjusting the radius of curvature and/or internal pressure of an eye (9) during surgery, comprising

the measurement system of claim 15,

a rinsing fluid supply apparatus (65, 69) for supplying a rinsing fluid into the eye (9),

an adjustment apparatus (67) for adjusting the pressure of the supplied rinsing fluid, and

a difference registering unit (161), connected to the evaluation device (157) in order to receive the established radius of curvature and/or the established internal pressure and to the adjustment apparatus (67) in order to output a correcting variable and designed to establish a deviation of the received radius of curvature and/or the received internal pressure from a target value and to calculate the correcting variable on the basis of the established deviation.