Doctors in Illinois have implanted the first permanent artificial silicon retinas in the eyes of three blind patients. The outcome of the pioneering bid to restore sight using microelectronics isn't yet known, but the undertaking is an important initial step toward realizing the goal of artificially assisted vision (see "Seeing Is Believing," TR May/June 1999).

The experiments were led by Alan Chow, a 48-year-old ophthalmologist who is president of Optobionics, the Wheaton, Ill., company that developed the hair-thin vision chips. The prototype devices are 2 millimeters across and contain some 3,500 microphotodiodes. Placed behind the retina, this collection of miniature solar cells is designed to convert natural light to electrical signals, which are then transmitted to the brain by the remaining healthy parts of the retina.