In July 2010 the United States Food and Drug Administration (FDA) approved the implantable miniature telescope (IMT) as a possible procedure to potentially improve vision in a small subset of patients with end-stage macular degeneration.
Surgically implanted in one eye, the IMT is a small telescope that replaces the natural lens and provides an image that has been magnified more than two times. The IMT is designed to magnify and project images onto a healthy portion of the retina. The device is intended to be implanted in only one eye; the non-implanted eye is used for peripheral vision. Pre- and post-operative training is needed to help patients learn how to see with the device implanted. According to the FDA, the device is used in patients ages 75 years and older with stable severe to profound vision impairment (when vision impairment has not changed over time) caused by blind spots (bilateral central scotoma) associated with end-stage AMD. These patients also have evidence of a visually significant cataract.
“Since so many millions of people around the world are affected by macular degeneration, we are always pleased when we see new treatments and devices available to patients,” said Stephen King, Interim CEO, AMD Alliance International. “People considering this treatment should ensure they understand the benefits, limitations and risks. We advise all patients who may be eligible for this device to talk with their full team of eye care specialists, from ophthalmologist or retinal specialist to low vision rehabilitation professional, to see if the IMT is right for them.”
The FDA cautions in their press release that “Because the IMT is a large device, implantation can lead to extensive loss of corneal endothelial cells (ECD), the layer of cells essential for maintaining the clarity of the cornea, and chronic endothelial cell loss. The chronic rate of endothelial cell loss is about 5 percent per year. Significant losses in ECD may lead to corneal edema, corneal decompensation, and the need for corneal transplant. In the study, 10 eyes had unresolved corneal edema, with five resulting in corneal transplants. The calculated five-year risk for unresolved corneal edema, corneal decompensation, and corneal transplant are 9.2 percent, 6.8 percent and 4.1 percent, respectively.”
Patients who receive the device agree to undergo training with an external telescope with a low vision specialist prior to implantation to determine whether adequate improvement in vision with the external telescope can be obtained, and to verify if the patient has adequate peripheral vision in the eye that would not be implanted. Patients also agree to participate in a post-operative visual training program.
As a condition of approval, VisionCare, the maker of the device, must conduct two studies, following up with existing patients and beginning a study of 770 new patients.
