Our sense of vision permanently captures, transmits and interprets enormous amounts of visual information. The amount of visual information that can be transmitted to the brain by the means of visual prosthesis will be severely limited and thus also limit the rehabilitation prospects of such devices. While several parameters contribute to the information content of visual stimuli, this chapter concentrates essentially on spatial resolution . The fi rst part of the chapter is dedicated to discuss the results of simulation studies of prosthetic vision on normal subjects. These studies aimed to respond to the question of how much visual information should be transmitted to the brain to rehabilitate patients. The amount of visual information, necessary to accomplish daily living tasks (such as reading, eye-hand coordination or whole body mobility) is task-dependent and not only image resolution itself, but also other parameters such as the size of the effective visual fi eld seem to be important. In the second part of the chapter we tried to discuss to which extent the information made available by the stimulation device is lost or degraded before reaching the brain. The experience with actual retinal implants shows us that only part of the information provided by the device fi nds its way to the central nervous system and that this information loss can be highly variable from patient to patient: the spatial resolution provided by the devices corresponds rarely to the spatial resolution perceived by the patients.