FDA Approves Implantable Miniature Telescope to Improve Sight
Yesterday, the Food and Drug Administration announced it’s approval of the Implantable Miniature Telescope (IMT), a small, surgically implanted telescope that replaces the natural lens and provides an image that has been magnified more than two times.
The IMT is approved for use to improve vision in some patients with end-stage age-related macular degeneration (AMD), a condition that mainly affects older people, damages the center of the retina (macula) and results in a loss of vision in the center of the visual field.
According to the National Eye Institute, about 8 million people in the United States have AMD and nearly 2 million of them already have significant vision loss which can make it difficult or impossible to recognize faces or perform daily tasks such as reading or watching television.
The IMT is surgically implanted in only one eye to improve central vision. The other eye is left alone to provide peripheral vision. The brain must fuse two views into a single image.
The IMT is available in two models: one that provides 2.2 times magnification and another 2.7 times magnification. The IMT is designed to magnify and project images onto a healthy portion of the retina.
Patients eligible for the IMT must be 75 years of age or 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. Often these patients will have evidence of a visually significant cataract.
All patients will need both presurgery and post-surgery rehabilitation. Before surgery, the patient needs to undergo training with an external telescope with a low vision specialist 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. After surgery, the patient will need to participate in a visual training program.
In a 219-patient, multi-center clinical study of the IMT, 90 percent of patients achieved at least a 2-line gain in either their distance or best-corrected visual acuity, and 75 percent of patients improved their level of vision from severe or profound impairment to moderate impairment.
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.
Because of these risks, the FDA is requiring that patients and their surgeons sign a detailed "acceptance of risk agreement" before surgery, acknowledging potential side effects — including corneal damage and worsened vision.
As a condition of FDA approval, the manufacturer, VisionCare Ophthalmic Technologies Inc. of Saratoga, Calif., must conduct two post-approval studies. In one study, VisionCare must continue follow-up on the subjects from its long-term follow-up cohort for an additional two years. Another study of 770 newly enrolled subjects will include an evaluation of the endothelial cell density and related adverse events for five years after implantation.
VisionCare, of Saratoga, Calif., is seeking Medicare coverage for the surgery and rehab costs, a package that it calls CentraSight. The company wouldn't estimate total costs but said the device itself costs $15,000.
For more information:
NIH: National Eye Institute - Age-Related Macular Degeneration