Silver Spring, MD-- The U.S. Food and Drug Administration has approved the Implantable Miniature Telescope (IMT), a small telescope that is surgically implanted in one eye to replace the natural lens and provide an image that has been magnified more than two times, improving vision in some patients with end-stage, age-related macular degeneration (AMD). Available in two models, one that provides 2.2 times magnification and another 2.7 times magnification, the IMT magnifies and projects images onto a healthy portion of the retina. The IMT 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.
In a 219-patient, multi-center clinical study of the IMT, 90% of patients achieved at least a two-line gain in either their distance or best-corrected visual acuity, and 75% of patients improved their level of vision from severe or profound impairment to moderate impairment.
But 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% 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%, 6.8 % and 4.1%, respectively.
To ensure that the risks of IMT implantation are sufficiently and consistently communicated to patients, the FDA and the manufacturer created detailed labeling, including an Acceptance of Risk and Informed Decision Agreement, which patients must complete prior to IMT implantation. The agreement provides a guide for patients and their physicians to discuss the risks associated with IMT implantation. Patients should be given adequate time to review all of the information regarding the IMT.
Patients 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 FDA approval, the manufacturer, VisionCare Ophthalmic Technologies Inc. of Saratoga, CA, 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.
