Automatic fitting for a visual prosthesis
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.
1. A method of stimulating visual neurons comprising:
stimulating visual neurons with a base level electrical charge;
detecting an indication of contraction of an iris;
varying said electrical charge in response to said indication of contraction of the iris; and
inducing visual percepts according to the varied electrical charge.
2. The method according to claim 1 , wherein said indication of contraction of the iris is an optical indication of contraction of the iris.
3. The method according to claim 1 , wherein said step of varying comprises increasing said electrical charge until change in said indication of contraction of the iris is detected.
4. The method according to claim 1 , wherein said step of varying comprises decreasing said electrical charge when a predetermined indication of contraction of the iris is reached.
5. The method according to claim 1 , further comprising:
recording a first electrical charge level when a first predetermined indication of contraction of the iris is recorded;
recording a second electrical charge level when a second predetermined indication of contraction of the iris 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 stimulation occurs through an array of electrodes in a stimulation mode and detection occurs through the array of electrodes in a detection mode.
7. The method according to claim 6 , wherein timing of a switching between the stimulation mode and the detection mode is a function of an amplitude of the electrical charge, the timing of the switching decreasing when the amplitude of the electrical charge increases.
8. The method according to claim 1 , wherein the detecting the indication of contraction of the iris is performed by an optical device aimed at the eye.
9. A method of stimulating visual neurons comprising:
stimulating visual neurons with an electrical charge;
detecting an indication of contraction of the iris by detecting muscle activity in the iris sphincter;
varying said electrical charge in response to said indication of contraction of the iris; and
inducing visual percepts according to the varied electrical charge.
10. The method according to claim 9 , wherein said step of varying comprises increasing said electrical charge until change in said muscle activity is detected.
11. The method according to claim 9 , wherein said step of varying comprises decreasing said electrical charge when a predetermined muscle activity is reached.
12. The method according to claim 9 , further comprising:
recording a first electrical charge level when a first predetermined muscle activity is recorded;
recording a second electrical charge level when a second predetermined muscle 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.
13. The method according to claim 9 , wherein stimulation occurs through an array of electrodes in a stimulation mode and detection occurs through the array of electrodes in a detection mode.
14. The method according to claim 13 , wherein timing of a switching between the stimulation mode and the detection mode is a function of an amplitude of the electrical charge, the timing of the switching decreasing when the amplitude of the electrical charge increases.