Apparatus and methods for mapping retinal function

• US 20080294066A1
• Filed: 06/09/2008
• Published: 11/27/2008
• 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: Hetling, John R., Ban, Tamas, Rahmani, Safa
• Granted Patent: US 8,118,752 B2
• Time in Patent Office: Days
• US Class Current: 600/558
• CPC Class Codes: A61B 5/398 Electrooculography [EOG], e.g. detecting nystagmus; Electroretinography [ERG]

Abstract

The present invention provides an electrode array device for simultaneously detecting electrical potentials at five or more locations on the anterior surface of an eye. The device comprises a dielectric lens substrate having a concave inner surface conforming to the anterior surface of the eye, and at least five recording electrodes positioned in relation to the inner surface of the lens substrate so as to make electrical connection with the anterior surface of the eye when the lens substrate is placed on the anterior surface of eye. Each recording electrode is in electrically conductive communication with a corresponding conductive contact, there being one conductive contact for each recording electrode. Each conductive contact is adapted for operable connection to signal processor, and each conductive contact is electrically insulated from the anterior surface of the eye. A computational method for analyzing electrophysiological potentials recorded at five or more locations on the anterior surface of the eye, which reflect the spatial distribution of activity of the retina, is also provided.

Claims

1. An electrode array device for simultaneously detecting electrical potentials at five or more locations on the anterior surface of an eye, the device comprising:

a dielectric lens substrate having a concave inner surface conforming to the anterior surface of the eye;

at least 5 recording electrodes positioned in relation to the inner surface of the lens substrate so as to make electrical connection with the anterior surface of the cornea of the eye when the lens substrate is placed on the anterior surface of the eye;

wherein each recording electrode is in electrically conductive communication with a corresponding conductive contact, there being one conductive contact for each electrode, each conductive contact being adapted for operable connection to a signal processor, and each conductive contact being electrically insulated from the anterior surface of the eye.

2. The device of claim 1 wherein the lens substrate includes 5 to 500 recording electrodes.

3. The device of claim 1 wherein each recording electrode comprises a conductive material deposited on the concave surface of the lens substrate.

4. The device of claim 1 wherein each conductive contact is positioned in the peripheral region of the lens substrate, and is connected to its corresponding recording electrode via an electrically conductive trace that is electrically insulated from the surface of the eye.

5. The device of claim 4 wherein each recording electrode comprises a cylindrical through-hole formed in the lens substrate adjacent to an un-insulated portion of its corresponding conductive trace, such that an electrically conductive connection is made between the conductive trace and the anterior surface of the eye when the lens substrate is placed on the anterior surface of the eye in the presence of an amount of an electrically conductive liquid or hydrogel sufficient to fill each through-hole and connect with the un-insulated portion of the trace.

6. The device of claim 5 wherein each through-hole is lined with a conductive material in electrically conductive connection with the conductive trace.

7. The device of claim 6 wherein the conductive material lining each through-hole comprises a metal, conductive polymer, or semiconductor material.

8. The device of claim 4 wherein each conductive trace, active electrode, and contact pad comprises a metal, conductive polymer, or semiconductor material.

9. The device of claim 1 wherein the lens substrate is configured to provide corrective refractive power to correct for defects in the visual acuity of the eye.

10. The device of claim 1 wherein the lens substrate is plano-concave.

11. The device of claim 1 wherein each recording electrode comprises a conductive element passing through the lens substrate.

12. The device of claim 1 further comprising one or more scleral recording electrodes positioned to make electrical contact with the sclera of the eye when the lens substrate is placed on the anterior surface of the eye, each scleral electrode being in electrically conductive communication with a corresponding conductive scleral electrode contact, there being one scleral electrode contact for each scleral electrode, each scleral electrode contact being adapted for operable connection to a signal processor, and each scleral electrode contact being electrically insulated from the anterior surface of the eye.

13. The device of claim 12 wherein each scleral recording electrode contact is positioned in a peripheral region of the lens substrate, and is connected to its corresponding scleral electrode either directly or via an electrically conductive trace that is electrically insulated from the anterior surface of the eye.

14. The device of claim 13 wherein each scleral recording electrode comprises a cylindrical through-hole formed in the lens substrate adjacent to its contact or to an un-insulated portion of its corresponding conductive trace, such that an electrically conductive connection is made between the contact and the anterior surface of the eye when the lens substrate is placed on the anterior surface of the eye in the presence of an amount of electrically conductive liquid or hydrogel sufficient to fill each through-hole and connect with the contact or un-insulated portion of the trace.

15. An electroretinographic (ERG) system comprising an electrode array device of claim 1 in which each recording electrode thereof is in electrically conductive communication with a signal processor including an amplifier, and capable of amplifying and detecting electrical potential signals from each electrode in a form suitable for data analysis.

16. The ERG system of claim 15 wherein the signal processor is incorporated in a computer.

17. The ERG system of claim 16 further comprising a computer programmed to generate a map of retinal activity from the electric potential signals.

18. A method for simultaneously recording electrophysiological potentials from five or more locations on the anterior surface of the eye of a subject comprising:

contacting the anterior surface of the eye with an electrode array device comprising a dielectric lens substrate having a concave inner surface conforming to the anterior surface of the eye;

wherein the substrate comprises at least 5 recording electrodes positioned in relation to the inner surface of the lens substrate so as to make electrical connection with the anterior surface of the eye;

each electrode being electrically connected to a signal processor including an amplifier, and capable of amplifying and detecting electrical potential signals; and

recording an electric potential signal from each electrode.

19. A computational method for analyzing electrophysiological potentials recorded at the anterior surface of the eye which reflect activity of a retina of an eye, comprising:

determining underlying spatially differentiated electrophysiological activity of the retina by comparing recorded eye surface potential data to estimated eye surface potentials obtained from a computational model of electrical and anatomical properties of the eye or the eye and head, the model incorporating electrical parameters and dimensions for multiple ocular structures, including at least the tear film, cornea, aqueous humor, lens, vitreous humor, retina, R-membrane, sclera, and extraocular adipose tissue;

wherein the eye surface potential data comprises at least 5 spatially differentiated electrical potentials simultaneously measured with an array of recording electrodes at predetermined electrode positions on the anterior surface of the eye.

20. The method of claim 19 wherein the retina in the model comprises a plurality of spatially distributed nodes, subsets of which correspond to anatomical structures within the eye;

the retina in the model being subdivided into a plurality of spatially distinct retinal source areas equal or greater in number to the number of recorded potentials;

a voltage, current, or charge magnitude being assigned to a subset of nodes within each retinal source area depending on the type of cell or neural pathway under analysis.

21. The method of claim 20, including the additional step of:

applying a transfer matrix to a first set of designated source magnitudes relating the electrophysiological potential contribution of each retinal source area to the electrophysiological potential at each electrode position on the anterior surface of the eye to provide a first set of estimated eye surface potentials.

22. The method of claim 21 additionally including the steps of:

calculating an error term representing the difference between the estimated eye surface potential and the measured eye surface potential at each position on the surface of the eye; and

computationally minimizing the difference between the estimated eye surface potentials and the measured eye surface potentials by iteratively changing the first set of designated source area magnitudes and recalculating the error term until the error term at each electrode position is below a predetermined maximum value or is at a minimum value, to thereby provide a final set of retinal source values that collectively represents a map of the electrophysiological potentials of the retina.

23. The method of claim 22, further including the step of displaying the final set of retinal source values in correct anatomical relation to the retina to provide a graphical map of spatial differences in retinal activity of the subject eye.

24. The method of claim 23, wherein the final set of retinal source values is displayed as predefined colors or shades of a single color, where each color or shade represents a magnitude or range of magnitude of an electrophysiological potential.