Mapping retinal function using corneal electrode array

• US 20070188710A1
• Filed: 02/15/2007
• Published: 08/16/2007
• Est. Priority Date: 02/16/2006
• Status: Active Grant

• Current Assignee: Board of Trustees of The University of Illinois
• Original Assignee: Board of Trustees of The University of Illinois
• Inventors: Ban, Tamas, Rahmani, Safa, Hetling, John
• Granted Patent: US 7,384,145 B2
• Time in Patent Office: Days
• US Class Current: 351/221
• CPC Class Codes: A61B 5/398 Electrooculography [EOG], e.g. detecting nystagmus; Electroretinography [ERG]

Abstract

A system and method for obtaining information about the spatial distribution of photoreceptor activity and neural activity in the retina using simultaneously recorded multiple biopotential signals. The information thus gathered is used to assess retinal dysfunction due to trauma or disease. The biopotential signals are recorded from the surface of the eye and head using a plurality of electrodes, including those integral to a contact lens. The biopotential signals are recorded before, during and after the presentation of an optical stimulus to the subject eye. The recorded biopotential signals are then analyzed and interpreted to reveal the distribution of photoreceptor activity and neural activity across the retina. The analysis and interpretation of the biopotential signals is quantitative, and makes use of an electromagnetic model of the subject eye. The subject may be animal or human.

Claims

1. A method of obtaining an electroretinogram, comprising:

providing an array of electrodes;

positioning the array of electrodes on a surface of a patient'"'"'s eye so that at least some of the electrodes contact the patient'"'"'s cornea;

illuminating the patient'"'"'s eye; and

monitoring the array of electrodes for electrical activity of the eye in response to the illumination.

2. The method of claim 1 wherein the patient'"'"'s eye is illuminated by passing light through the array of electrodes.

3. The method of claim 2 wherein the array of electrodes is at least partially transparent to the illumination.

4. The method of claim 2 wherein the array of electrodes comprises an openwork array of spaced apart conductive members.

5. The method of claim 2 wherein the array of electrodes comprises an array of conductive members carried on a dielectric carrier.

6. The method of claim 5 wherein the dielectric carrier comprises a contact lens having an inner surface facing the patient'"'"'s eye and an opposing outer surface.

7. The method of claim 6 wherein the conductive members are carried on the inner surface of the contact lens.

8. An electrode array for electroretinography comprising:

a contact lens body having an outer periphery, an inner surface facing a patient'"'"'s eye and an opposing outer surface;

an array of conductive members carried on the inner surface of the contact lens body so as to be integral therewith;

the array of conductive members being positioned about the contact lens body so that at least a portion of the conductive members contacts the patient'"'"'s cornea;

the array of conductive members being spaced apart from one another so as to be substantially transparent to full-field stimulation of the patient'"'"'s eye;

the conductive members extending to the outer periphery of the contact lens body; and

connections for electrically connecting the conductive members to electrical circuitry external to the electrode, each connection being provided at the outer periphery so as to be integral with the contact lens body

wherein a substantial amount of the full-field stimulation passes the conductive members and reaches the patient'"'"'s cornea.

9. The electrode array of claim 8 wherein at least five conducting members are carried on the contact lens body.

10. The electrode array of claim 8 wherein some of the conductive members contact the patient'"'"'s sclera.

11. The electrode array of claim 8 wherein the conducting members comprise recording electrodes receiving electrical stimulation from the surface of the patient'"'"'s eye.

12. The electrode array of claim 8 wherein the contact lens comprises poly(methyl methacrylate).

13. A computational method for use in analyzing potentials recorded at a cornea which reflect activity of a retina of an eye, comprising:

providing an array of electrodes;

placing the electrodes in electrical contact with the cornea;

illuminating the eye so as to cause retinal activity;

measuring electrophysiological potentials at the cornea in response to the illumination with the array of electrodes; and

solving for retinal information based on the electrophysiological potentials made at the cornea.

14. The electrode of claim 13 wherein the retinal information comprises either retinal potentials or retinal currents.

15. The method of claim 13 wherein the step of solving comprises adapting techniques developed for functional brain mapping of human patients based on the electroencephalographic recordings.

16. The method of claim 13 wherein the step of solving comprises adapting the techniques for mapping of cardiac activity of human patients based on measurements of cardiac potentials made at the surface of the heart or torso.

17. The method of claim 13 wherein the eye is illuminated by passing light through the array of electrodes.

18. The method of claim 17 wherein the array of electrodes is at least partially transparent to the illumination.

19. The method of claim 13 wherein the step of placing the electrodes in electrical contact with the cornea comprises the steps of providing a contact lens body having an inner surface facing the patient'"'"'s eye, placing at least five electrodes on the inner surface and fitting the contact lens to the patient'"'"'s eye.

20. A finite-element model of the eye for use in analyzing a cornea and a retina of an eye, comprising:

determining anatomical structures of the eye and tissues and materials surrounding the eye;

determining electrical properties of each structure; and

stimulating retinal activity via a time-varying change in the electrical activity either within or across the retina.

21. The method of claim 20 wherein the electrical activity comprises a time-varying change in charge distribution or local currents within or across the retina.

22. The method of claim 20 further comprising determining an optimal design of a contact lens carrying the array of conductive members.

23. A method of measuring electrophysiological potentials at a cornea, where the potentials originate in the retina, comprising:

providing an array of electrodes;

placing the electrodes in electrical contact with the cornea;

illuminating the eye with photic stimuli that elicit responses from specific cell types or functional pathways in the retina; and

measuring electrophysiological potentials made at the cornea in response to the illumination with the array of electrodes to obtain local differences in function of the cell types or functional pathways.

24. The method of claim 24 wherein the eye is illuminated by passing full-field spatially invariant stimulation through the array of electrodes.

25. The method of claim 25 wherein the array of electrodes is at least partially transparent to the illumination.

26. The method of claim 26 wherein the array of electrodes comprises an openwork array of conductive members.

27. The method of claim 26 wherein the array of electrodes comprises an array of conductive members carried on a dielectric carrier.

28. An assembly for electroretinographic recording, comprising

a contact lens body having an outer periphery, an inner surface facing a patient'"'"'s eye and an opposing outer surface;

a first array of recording electrodes carried on the inner surface of the contact lens body so as to be integral therewith;

the first array of recording electrodes being positioned about the contact lens body so that at least a portion of the recording electrodes of the first array contacts the patient'"'"'s cornea;

the first array of recording electrodes being spaced apart from one another so as to be substantially transparent to full-field stimulation of the patient'"'"'s eye;

the first array of recording electrodes extending to the outer periphery of the contact lens body;

connections for electrically connecting the first array of recording electrodes to electrical circuitry external to the electrode, each connection being provided at the outer periphery so as to be integral with the contact lens body;

a second array of recording electrodes being positioned either around the patient'"'"'s eye for contact with the patient'"'"'s skin or in contact with the patient'"'"'s scalp; and

electrical leads connected to the first and the second arrays of recording electrodes, for connection to external circuitry for receiving responses detected by the recording electrodes

wherein a substantial amount of the full-field stimulation passes the conductive members and reaches the patient'"'"'s retina.

29. The electrode of claim 29 wherein at least five conducting members are carried on the contact lens body.

30. The electrode of claim 29 wherein some of the recording electrodes contact the patient'"'"'s sclera.