End-stage age-related macular degeneration (AMD) is the most advanced form of the disease that is the leading cause of blindness in the United States. It results in a permanent loss of central vision, making it extremely difficult to see or identify people and objects. Unlike less severe forms of AMD, end-stage AMD causes irreparable damage to the macula, the small area of the retina responsible for central vision, and does not respond to treatment by glasses, drugs or artificial lenses implanted during cataract surgery. For these nearly 2 million patients, the world seems to disappear before their eyes, making it difficult to perform everyday tasks.
For decades, these patients have had no remedy for their sight loss, but today a relatively new technology the size of a pea is helping them see their loved ones’ faces, read books and reassume other daily tasks that require detailed vision, reopening a window to life.
The technology is a surgically implantable miniature telescope (IMT) which is the first low-vision device covered by Medicare. Though not a cure or quick fix, the IMT can partially restore vision loss for some patients with advanced AMD who have exhausted all other forms of treatment.
How The Telescope Works
The IMT was approved by the Food and Drug Administration in 2010. The tiny telescope is implanted in the front of one eye after removal of the natural lens. Designed to work like a telephoto camera lens, the IMT magnifies images that come into the eye by more than two times and projects them onto the healthy part of the retina to help improve central vision. This allows the patient to discern images that may have been unrecognizable or difficult to see. The non-implanted eye continues to see with peripheral vision, while the eye with the telescope takes on detailed central vision. Implanted patients need therapy to help retrain the brain to use each eye differently.
Who Is the Telescope For?
Though a promising tool for some, the IMT is not for everyone with AMD due to the requirements of ongoing post-operative therapy.
Candidates must go through a detailed screening process involving two types of ophthalmologists — cornea surgeon and vitreoretinal specialist — plus an occupational therapist and a low-vision optometrist. That’s because IMT treatment is a very labor-intensive process requiring an average of 12 visits across four to six months, plus ongoing “homework” post-operatively to keep the eye proficient at seeing with the device.
“The involvement is more than people realize. The whole process requires a lot of training, counseling and an intense commitment from the patient,” says Abdhish R. Bhavsar, M.D., a retina surgeon and clinical spokesperson of the American Academy of Ophthalmology.
That’s why IMT candidates are carefully selected, looking at their overall medical, psychological and social status. The minimum requirements are that the patient:
- Be sixty-five or older
- Have AMD in both eyes with vision of 20/160 or worse
- Have stable eyes that are not leaking blood or fluid within the eye
- Have no previous cataract surgery
- Be well informed with realistic expectations about vision improvement
Next, eligible patients are required to go through testing with an external telescope that simulates the effect of an IMT to see whether vision improvement would be possible and how they may adjust to the difference in vision between their two eyes.
“The evaluation process is a slow, careful journey, like traveling a road with many checkpoints, to give patients an accurate expectation of how they will do with the telescope,” says Henry L. Hudson, M.D., who was a principal investigator in the trial for FDA approval, and has implanted 33 patients with the IMT.
Additionally, candidates must make an up-front commitment to vision training after their surgery. They should have family members or friends in close proximity who will provide transportation and support. An optimistic outlook helps, too. “For every 100 patients that are medically eligible, only about one quarter will go on to qualify for the surgery; we want to be highly confident that the patient will be successful,” says Dr. Hudson.
Surgery and Post-Op: What to Expect
The IMT surgery itself is an outpatient procedure performed by a cornea surgeon. Lasting approximately one hour, the surgeon will numb the eye, enlarge the pupil with special drops, remove the eye’s natural lens and replace it with the telescope, then close the incision with sutures. Risks are similar to those involved in cataract surgery, and include bleeding, infection, retinal detachment and long-term swelling or cloudiness caused by corneal endothelial cell loss.
After the surgery, patients begin a months-long process of intensive visual rehabilitation to train their eyes to see with the telescope. Goal-oriented and individualized to each patient’s unique visual needs, therapy includes learning how to find and focus on objects of interest, as well as scan, trace and track moving objects. Patients must also learn how to use the eye without the telescope for activities that require peripheral vision, such as walking and getting around.
Living with the world magnified in one eye only can be very challenging, cautions Dr. Bhavsar. “Some patients adjust to it, but others may have a hard time. Reconciling the difference between what the brain is seeing with each eye can be overwhelming.”
Dr. Hudson has found that the majority of patients learn to either ignore the non-implanted eye, or “cross wink” — keeping one eye open at a time to manage the disparity between what each eye sees. In his experience, those patients who have experience using tools such as video, or handheld or eyeglass-mounted magnifiers adjust to the telescope more easily.
Success with the implant is measured by improvement in everyday visual function rather than absolute visual acuity. Despite this, a clinical study of more than 200 patients found clinically significant visual acuity improvements five years after surgery. In this same study, the device was removed from eight patients because they were dissatisfied and from four patients because of complications.
Even the most successful implanted patients won’t be able to drive, but with therapy and training, they should regain the ability to make a cup of coffee, watch television and get around their home independently.
“For the right, motivated individual, the IMT can bring a return to many of the things they love,” said Dr. Hudson.