Channel interaction generated by simultaneous electrical stimulation of neighboring electrodes is generally undesirable. However, channels interaction, or virtual channels, can be used in a controlled manner to increase the number of perceptible electrodes for retinal prosthesis patients. Virtual channels have been used successfully in the cochlear prosthesis systems to increase the number of perceptible channels or electrodes. In this paper, we analyze and study the condition for generating virtual channels in retinal prostheses. A finite element model of the retina with four electrodes was created. The conditions for generating virtual channels were studied by adjusting the ratio of the input voltage applied to neighboring electrodes. Experimental studies in cochlear prostheses show the existence and usefulness of virtual channels.