Method and apparatus for fitting a visual prosthesis using electrically evoked electroretinograms

A method of fitting an implantable neural stimulator comprising:

• a. providing an implantable neural stimulator including electrical components and an array of electrodes suitable to stimulate visual neurons within an eye and suitable to be implanted in the eye;
• b. providing a computer, the computer completing steps c through m under automatic control of the computer;
• c. stimulating the visual neurons with a series of electrical stimulation signals through a selected subset of the array of electrodes to the eye;
• d. using an electroretinogram to record levels of measured neural activity induced by the step of stimulating the visual neurons to produce electroretinogram signals of the measured neural activity;
• e. filtering the electroretinogram signals to remove signals from eye movement or pupil responses;
• f. applying a wavelet transform to the electroretinogram signals to filter out any electroretinogram artifacts caused by the electrical components in the implantable neural stimulator;
• g. discarding the electroretinogram signals with large artifacts;
• h. averaging epochs in the electroretinogram signals;
• i. comparing each level of the neural activity measured by the electroretinogram to the stimulation signals;
• j. determining a relationship between the stimulation signals and each level of the neural activity measured by the electroretinogram;
• k. repeating steps c-j for different selected subsets of the array of electrodes;
• l. determining and storing desired levels of stimulation based upon the comparison of the level of the neural activity measured by the electroretinogram and a stimulation level of the stimulation signals;
• and
• m. stimulating the visual neurons in the eye with the implantable neural stimulator to induce the perception of vision based on the desired levels of stimulation.