What retinal implant should you be eyeing?

In the realm of retinal implants, there exists three types, epiretinal, subretinal, and cortical. All three show promise to restoring vision in some manner, though each have their associated benefits and risks.
Epiretinal implants, are applied to the outermost layer of the retina, this receieves signals from a peripheral camera and then transmits these electrical impulses of the image to the intact retina and optic nerve. The benefits of an epiretinal implant is that the camera could and conversion process could be tuned and more honed while implanted, and makes replacement/upgrading of the camera an easier process should it be neccessary. Negatives about this system are obviously the fact that it's asthetics aren't the most pleasing, epiretinal implants also can't be used on damaged retinas. The next form of implants, subretinal implants, is put on the photoreceptor level of the retina. This chip does all the ligth detection and conversion work there, without a camera. This system is good because it can be used in persons who have suffered from retinal degeneration. The negatives to this procedure is that it's slightly more invasive, and that the image could be worse than that of epiretinal. The final form of retinal implants involves a cortical implant. This implant is used in patients who have deteriorated optical nerves. This method involves direct interaction with the brain via the visual cortex. The visual cortex is hooked up to a camera setup which converts the images into electrical impulses that travel to the brain. The problem with this system is: cost, dangers of direct brain implantation ie. menengitis and scar tissue formation, not that great of a resolution, and asthetic problems. The good about it is that it works for patients who have optical nerve degeneration.
The best of these systems is subretinal implants, this is because they are less noticeable, require less maitenence, is pretty safe, and does pretty much just as well image wise as epiretinal implants.

http://www.seeingwithsound.com/etumble.htm
http://www.opticsreport.com/content/article.php?article_id=1007