April 23, 2008 — Might an implantable scaled down telescope donate macular degeneration patients a vision boost when they run out of other options? An FDA admonitory panel takes up that question later this week.
Macular degeneration, the leading cause of severe vision loss in individuals over age 60, gradually takes central vision, which is needed for errands such as reading and driving. Central vision continuously goes from being a little fluffy to approach blindness.
The Implantable Smaller than expected Telescope (IMT), made by VisionCare Ophthalmic Technologies of Saratoga, Calif., is the primary of its kind. It’s 4 millimeters long and planned for individuals with central vision loss in both eyes from end-stage age-related macular degeneration.
„End-stage“ implies that „there’s nothing we are able to do that will medically move forward that eye,“ says ophthalmologist Charge Lloyd, MD, who writes WebMD’s Eye on Vision web journal.
Good candidates for the telescope have extremely impeded vision but aren’t completely daze, Lloyd says. Patients can as it were get the telescope in one eye, since they require their other eye for peripheral vision, which the telescope decreases.
In the telescope’s clinical trial, patients‘ vision moved forward and so did their quality of life. „It’s a promising device,“ Lloyd says.
Kathryn Colby, MD, PhD, director of joint clinical research at the Massachusetts Eye and Ear Clinic in Boston, agrees. „I think it’s a very great gadget for people for whom there are no other options,“ says Colby, who taken part in the telescope’s clinical trial. „I have likely 60 patients on a waiting list that are waiting for the FDA to form its choice.“
But the telescope isn’t a remedy — and it does have risks. „It doesn’t provide individuals back their 20-year-old eyes which are ordinary in every other way. So it’s very critical for patients to have realistic desires going into this,“ Colby says.
Almost Macular Degeneration
„The macula is the central-most area of your vision,“ Lloyd says. „Think approximately a map of the United States — the macula of your retina is like Kansas City. It’s a generally little piece of genuine domain compared to the entire outline. But in any case, so much of our visual input, which is 70% of what we encounter in life, is processed by that little small island of thick photoreceptors.“
In end-stage macular degeneration, „that’s gone,“ Lloyd says. But „you still have plenty of other genuine bequest that’s not as good, not as rich in photoreceptors.“
„Unfortunately,“ Lloyd says, the thickness of the photoreceptors in these remote regions is not as precise as it was within the macula… It’s not the same as seeing 20-20, but it’s certainly much better.“
How the Implantable Telescope Works
The telescope amplifies images by enlisting other parts of the retina to make up for the loss of the macula. „What it does is it extends the image that the patients can see to compensate for their macular degeneration, Colby says.
In the telescope’s clinical trial, 206 patients took eye tests some time recently getting the implantable miniature telescope. One year later, 67% of them seem examined at slightest three extra lines on the doctors‘ eye chart, compared to their eye test comes about some time recently getting the telescope.
„One of the patients I implanted really was able to return to a long-loved avocation of sculpting that he had had to donate up,“ Colby says.
Implanting the telescope is „challenging surgery,“ says Colby, who composed a paper almost the method in the August 2007 edition of the Files of Ophthalmology.
Four millimeters may sound little, but for the eye, „it’s a expansive device, so it needs to be set in the eye carefully to dodge harming other structures inside the eye,“ Colby says.
Those structures include the cornea, which is the eye’s peripheral layer.
Within the telescope’s clinical trial, patients had misplaced 25% of certain corneal cells one year after surgery. That didn’t meet the study’s benchmark of losing no more than 17% of those cells. Cornea masters met that goal, but not all of the surgeons who took part within the study were cornea specialists, Colby notes.
The trial’s results, published in Ophthalmology in November 2006, show that most of the corneal cell misfortune occurred from postsurgery swelling, not because of progressing trauma caused by the telescope.
Lloyd notes that after getting the telescope, a few patients in the clinical trial afterward required a corneal transplant. That will be in part because of their advanced age (participants were 76 years old, on average), Lloyd says.
Tips for Patients
In the event that the FDA endorses the implantable smaller than expected telescope, Lloyd and Colby have some exhortation for patients.
First, keep your expectations reasonable. For instance, „it’s not practical to hope that you’re getting to be able to drive,“ Colby says.
Second, choose your surgeon carefully. Lloyd suggests asking these questions:
What are the dangers, the benefits, and the alternatives? Where did you learn how to do this procedure? How many of these operations have you done? What is your success rate with this operation?
„It’s early going. These things are progressing to require a lot of care and a part of follow-up, and a steep learning bend,“ Lloyd says.