Automatic fitting for a visual prosthesis

• US 20070093876A1
• Filed: 06/08/2004
• Published: 04/26/2007
• Est. Priority Date: 06/08/2004
• Status: Active Grant

• Current Assignee: Second Sight Medical Products, Inc.
• Original Assignee: Second Sight Medical Products, Inc.
• Inventors: Greenberg, Robert, Williamson, Richard
• Granted Patent: US 7,483,751 B2
• Time in Patent Office: Days
• US Class Current: 607/53
• CPC Class Codes: A61N 1/0543 Retinal electrodes
• CPC Class Codes: A61N 1/36046 of the eye

Abstract

The invention is a method of automatically adjusting an electrode array to the neural characteristics of an individual patient. By recording neural response to a predetermined input stimulus, one can alter that input stimulus to the needs of an individual patient. A minimum input stimulus is applied to a patient, followed by recording neural response in the vicinity of the input stimulus. By alternating stimulation and recording at gradually increasing levels, one can determine the minimum input that creates a neural response, thereby identifying the threshold stimulation level. One can further determine a maximum level by increasing stimulus until a predetermined maximum neural response is obtained.

Claims

1. A method of stimulating visual neurons comprising:

stimulating visual neurons with an electrical charge;

detecting an indication of neural activity; and

varying said electrical charge in response to said indication of neural activity.

2. The method according to claim 1, where said step of detecting indication of neural activity is electrically detecting neural activity.

3. The method according to claim 1, wherein said step of varying comprises increasing said electrical charge until indication of neural activity is detected.

4. The method according to claim 1, wherein said step of varying comprises decreasing said electrical charge when a predetermined level of neural activity is reached.

5. The method according to claim 1, further comprising:

recording a first electrical charge level when a first predetermined level of neural activity is recorded;

recording a second electrical charge level when a second predetermined level of neural activity is recorded; and

stimulating said visual neurons according to an input signal between said first electrical charge level and said second electrical charge level.

6. The method according to claim 1, wherein said step of detecting neural activity comprises detecting muscle activity in the iris sphincter.

7. The method according to claim 1, wherein said step of detecting neural activity comprises detecting neural activity in the visual cortex.

8. The method according to claim 1, wherein said step of detecting neural activity comprises detecting neural activity in the retina.

9. The method according to claim 1, wherein said step of stimulating and said step of detecting are sequential using a single electrode.

10. The method according to claim 1, further comprising a delay period between said step of stimulating and said step of detecting wherein said delay period varies according to the level of input stimulus.

11. The method according to claim 1, wherein said step of stimulating and said step of detecting are concurrent using different electrodes.

12. A visual stimulator comprising:

a variable output stimulator coupled to an electrode suitable for contact with retinal tissue;

a neural activity recorder coupled to an electrode suitable for contact with neural tissue;

a control device for controlling said stimulator in response to said recorder.

13. The visual stimulator according to claim 12, wherein said neural activity recorder is a visual cortex activity recorder.

14. The visual stimulator according to claim 12, wherein said neural activity recorder is an iris sphincter activity recorder.

15. The visual stimulator according to claim 12, further comprising a memory for storing data from said recorder.

16. The visual stimulator according to claim 15, wherein said memory stores a minimum and a maximum stimulation level.

17. The visual stimulator according to claim 16, wherein said minimum is the lowest stimulation level where neural activity is detected.

18. The visual stimulator according to claim 16, wherein said control device stimulates visual neurons between said minimum and said maximum according to an external input.

19. The visual stimulator according to claim 18, wherein said external input is a video capture device.

20. The visual stimulator according to claim 12, wherein said electrode coupled to said stimulator is adjacent to said electrode coupled to said recorder.

21. The visual stimulator according to claim 12, wherein said electrode is suitable for implantation in an eye.

22. A visual prosthesis comprising:

a variable output stimulator coupled to a plurality of electrodes suitable for contact with a visual neurons;

a neural activity recorder coupled to a plurality of electrodes suitable for contact with visual neurons;

a first memory for storing a preset minimum level of neural activity and a preset maximum level of neural activity;

a control device for controlling said stimulator according to said recorder, and determining a minimum level of stimulation causing said minimum level of neural activity and a maximum level of stimulation causing said maximum level of neural activity; and

a second memory for storing said minimum level of stimulation and said maximum level of stimulation.

23. The visual prosthesis according to claim 22, wherein said minimum level of stimulation and said maximum level of stimulation are determined separately for each electrode.

24. The visual prosthesis according to claim 22, further comprising a video capture device coupled to said control device for controlling said stimulator between said minimum stimulation level and said maximum stimulation level according to a video image.

25. The visual prosthesis according to claim 22, wherein said minimum stimulation level and said maximum stimulation level are recalibrated on a periodic basis.

26. A method of stimulating visual neurons comprising:

stimulating visual neurons with a base level electrical charge;

detecting an optical indication of neural activity; and

varying said electrical charge in response to said optical indication of neural activity.

27. The method according to claim 26, wherein said optical indication of neural activity is movement of the iris.

28. The method according to claim 26, wherein said optical indication of neural activity is light output from luminescent pigment in the vicinity of visual neurons.

29. The method according to claim 26, wherein said step of varying comprises increasing said electrical charge until change in said optical indication of neural activity is detected.

30. The method according to claim 26, wherein said step of varying comprises decreasing said electrical charge when a predetermined optical indication of neural activity is reached.

31. The method according to claim 26, further comprising:

recording a first electrical charge level when a first predetermined optical indication of neural activity is recorded;

recording a second electrical charge level when a second predetermined optical indication of neural activity is recorded; and

stimulating said visual neurons according to an input signal between said first electrical charge level and said second electrical charge level.