FDA approves first implantable miniature telescope to improve sight
of AMD patients
12 July 2010
The US FDA has approved the Implantable Miniature Telescope
(IMT) produced by VisionCare Ophthalmic Technologies Inc. to improve
vision in some patients with end-stage, age-related 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.
AMD, a condition that mainly affects older people, damages the
centre of the retina (macula) and results in a loss of vision in the
centre of the visual field. About 8 million people in the United
States have AMD and nearly 2 million of them already have
significant vision loss, according to the National Eye Institute.
AMD can make it difficult or impossible to recognize faces or
perform daily tasks such as reading or watching television.
"This innovation has the potential to provide many people with an
improved quality of life," said Jeffrey Shuren, M.D., J.D., director
of the FDA's Center for Devices and Radiological Health.
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. The IMT is intended to be implanted in only one eye; the
non-implanted eye is used for peripheral vision.
The IMT is used in patients aged 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.
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.
In a 219-patient, multi-center clinical study of the IMT, 90% of
patients achieved at least a 2-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
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.
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.