Retinal prosthesis development continues on positive path

Los Angeles-A clinical trial of a prototype intraocular retinal prosthesis continues to produce encouraging results during ongoing follow-up. Meanwhile, the development program is on schedule for a higher-density device that investigators hope will enable unaided mobility for totally blind individuals, according to Mark S. Humayun, MD, PhD.

"Model 1" of the intraocular retinal prosthesis has been implanted in six eyes of six patients with bare or no light perception vision from retinitis pigmentosa as part of an Investigational Device Exemption trial.

The first device was placed in February 2002, and the final patient in the study received the implant in June 2005.

Safety assessment is the primary objective of the clinical feasibility study of Model 1. From that perspective, the results have been very favorable as biocompatibility is good and there have been no problems with infection, scarring, retinal damage, or intraocular bleeding, Dr. Humayun said.

"Model 2" has been in parallel development over the last 5 years. Compared with its predecessor, Model 2 features a fourfold smaller extraocular component but it has four times as many channels of current output. With the ability to capture 64 channels of visual information rather than just 16, it is hoped Model 2 will provide improved-quality images, Dr. Humayun said.