During the implant procedure, surgeons first remove cataracts from the eye. (Because both macular degeneration and cataracts are age related, most patients with end-stage macular degeneration also have cataracts.) They then insert the telescope, which is held in place by the resident tissue.
The device is implanted in only one eye–patients use this eye for detailed vision and the untreated eye for peripheral vision. That takes some getting used to, says Peli. “Instead of using two parts of the same eye, they must switch between two eyes; if they see someone coming but can’t tell who it is, they need to switch to other eye.”
One safety concern associated with the implant is loss of the endothelial cells that are responsible for keeping the cornea transparent. While cell loss occurs with any eye surgery, implantation of the telescope requires a larger incision than typical cataract surgery and thus destroys more endothelial cells. However, scientists have found that cell loss stabilizes over time. Patients with the implant lose about 3 percent of their endothelial cells per year, compared to about 2.5 percent to 3 percent for patients undergoing traditional cataract surgery. Because endothelial cells do not replicate, substantial loss of these cells can worsen vision.
The FDA is expected to approve the telescope, as the agency usually follows the advice of its advisory panels. VisionCare plans to market the device following FDA approval, estimated for late 2009. The device has already been approved for use in Europe, though the company plans to launch the product first in the United States.