Visual prosthesis fitting
Methods and devices for fitting a visual prosthesis are described. In one of the methods, threshold levels and maximum levels for the electrodes of the prosthesis are determined and a map of brightness to electrode stimulation levels is later formed. A fitting system for a visual prosthesis is also discussed, together with a computer-operated system having a graphical user interface showing visual prosthesis diagnostic screens and visual prosthesis configuration screens.
1. A method for fitting a visual prosthesis having a plurality of electrodes, the method comprising:
selecting one electrode from among a first electrode and subsequent electrodes as a standard electrode;
determining a first perceived brightness level on the standard electrode by patient feed back, wherein the first perceived brightness level on the standard electrode is elicited by a first stimulation amplitude;
approximating the first perceived brightness level on a second electrode by setting a second stimulation level to be applied to the second electrode to the first stimulation amplitude applied on the standard electrode;
refining the second stimulation amplitude on the second electrode using further patient feedback to elicit the first perceived brightness level on the second electrode; and
creating and storing a map of brightness to electrode stimulation amplitudes based on the established stimulation amplitudes for the standard electrode and the second electrode,
wherein the first and second stimulation amplitudes are provided by a stimulation system.
2. The method of claim 1 , further comprising:
determining a second perceived brightness level on the standard electrode by patient feedback, wherein the second perceived brightness level on the standard electrode is elicited by a third stimulation amplitude;
approximating the second perceived brightness level on the second electrode by setting a fourth stimulation amplitude to be applied to the second electrode to the third stimulation amplitude applied on the standard electrode; and
refining the fourth stimulation amplitude on the second electrode using further patient feedback to elicit the second perceived brightness level on the second electrode,
wherein the third and fourth stimulation amplitudes are provided by the stimulation system.
3. The method of claim 1 , wherein the first perceived brightness level on the standard electrode and the first perceived brightness level on the second electrode are threshold levels.
4. The method of claim 2 , wherein the second perceived brightness level on the standard electrode and the second perceived brightness level on the second electrode are maximum levels.
5. The method of claim 4 , wherein the maximum level is a level of three quarters of a safety limit.
6. The method of claim 4 , wherein the maximum level is a maximum comfort level for the patient.
7. The method of claim 2 , wherein the first perceived brightness level on the first electrode and subsequent electrodes is determined through a 150-750 ms train of 10-100 Hz pulses.
8. The method of claim 1 , wherein the standard electrode is the electrode having a median threshold value.
9. The method of claim 1 , wherein the patient is subjected to a brightness comparison between the standard electrode and each electrode different from the standard electrode.
10. The method of claim 1 , wherein the patient is subjected to a brightness comparison by rating brightness of a clump of electrodes.
11. The method of claim 4 , wherein the maximum level on the first electrode and subsequent electrodes is determined by gradually increasing an amplitude of stimulation pulses.
12. The method of claim 4 , wherein determination of threshold and maximum levels on the electrodes is performed by converting a video camera input to a pattern of electrical stimulation.
13. The method of claim 1 , wherein the refining the second stimulation amplitude comprises:
decreasing the second stimulation amplitude on the second electrode if perceived brightness of the second electrode based on patient feedback is brighter than the first perceived brightness level on the standard electrode; and
increasing the second stimulation amplitude on the second electrode if the first perceived brightness level on the standard electrode is brighter than perceived brightness of the second electrode based on patient feedback,
wherein the decreasing and the increasing is performed by the stimulation system.
14. The method of claim 1 , further comprising, for each particular electrode in the plurality of electrodes aside from the standard electrode and the second electrode:
approximating the first perceived brightness level on a particular electrode by setting an electrode stimulation amplitude to be applied to a particular electrode to the first stimulation amplitude applied on the standard electrode;
refining the electrode stimulation amplitude on the particular electrode using further patient feedback to elicit the first perceived brightness level on the particular electrode; and
creating and storing a map of brightness to electrode stimulation amplitudes based on the established stimulation amplitudes for each electrode,
wherein the electrode stimulation amplitude is provided by the stimulation system.
15. The method of claim 1 , wherein the refining the second stimulation amplitude comprises adjusting at least one of pulse width, duration of a cathodic phase, duration of an anodic phase, and duration between an end of either the cathodic phase or the anodic phase and a beginning of the other phase, wherein the adjusting is performed by the stimulation system.
16. The method of claim 1 , wherein the standard electrode is an electrode having a maximum comfort level for the patient that is above a safety limit of the electrode.