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Implantable Miniature Telescope (IMT)

Age-related macular degeneration is a common cause of vision loss, especially in older people. There are two kinds of AMD: wet and dry. While most people with AMD have the dry form, wet AMD is responsible for 90% of cases of severe vision loss related to AMD.1 Many treatments for advanced AMD are for wet AMD, such as anti-VEGF injections and laser procedures. Treatment with the implantable miniature telescope (IMT), however, can be used for end-stage AMD from either wet or dry AMD.2 In AMD, vision loss is often centrally located, causing a “blind spot” in the center of your vision. The IMT is meant to reduce the relative size of that central blind spot by enlarging the overall image.

How does the IMT work?

The IMT device itself is small – about the size of a pea. It is implanted into the eye following cataract surgery, where the natural lens of the eye is removed. Light entering the eye is magnified by the telescope, projecting a larger image onto the retina. This improves your vision because any dark or blurry spots will appear relatively smaller against a magnified image. While the IMT does not heal the damaged areas of your macula, it does use the healthy parts of your retina to compensate for the damage already done by AMD. For example, whereas a dark spot might have blacked out someone’s entire face before IMT, with the device you may only see one or two dark spots in certain areas of a person’s face. Of note, the device is only designed to be placed in one eye.

Qualifying for surgery

There are strict guidelines that help determine who is a good candidate for IMT surgery. These include1,2:

  • Having end-stage AMD in both eyes, either wet or dry
  • Other AMD treatments, including anti-VEGF therapy, are no longer effective
  • You have not had cataract surgery in the eye in which the telescope is implanted (this might change, as this is being studied)
  • You are at least 65 years old
  • Visual acuity between 20/160 and 20/800

To see if you are a candidate for the surgery, you’ll have extensive testing with an external telescope to see how beneficial the surgery might be, and you’ll see an eye doctor who specializes in low vision so they can do various tests and exams.

Risks

Any surgery and medical procedure or treatment carries potential risks. Risks of IMT surgery can include2:

  • All risks of cataract surgery apply, which may include infection, bleeding, inflammation, and retinal detachment
  • Damage to cells of the inner cornea due to aspects of the surgery in which the cornea is stretched in order to insert the IMT; a hazy cornea can affect vision, and in severe cases the cornea may need to be replaced
  • It might take a long time to adjust to the new vision and demands of rehabilitation and vision training
  • Potential need for additional surgery if the IMT dislocates or other complications arise

Post-Surgery Vision

After the IMT surgery, you will need to take part in vision rehabilitation. An anti-inflammatory drug regimen is also usually prescribed, to keep swelling and inflammation controlled during the recovery process.1 Spectacles are prescribed after the surgery takes place, and vision rehabilitation with a low vision specialist started to help train your brain to choose which eye to use when looking at something close up, head on, and peripherally.2 The image that the IMT provides you is donut-shaped, and this takes time to get used to, as well. Your low vision specialist can show you how to adapt to your new vision.

What can you do?

If you have end-stage AMD that isn’t responding to other treatments, you might be a candidate for IMT surgery. Talk with your doctor about the risks and benefits, and whether you might benefit from it. There are real risks to the surgery, and your doctor can help you determine whether it’s a good fit for your vision, general health, and lifestyle.

Jaime R. Herndon | January 2019
  1. Hau V, London N, Dalton M. The treatment paradigm for the implantable miniature telescope. Ophthalmol Ther. 2016; 5(1): 21-30. Doi: 10.1007/s40123-016-0047-5. Accessed November 21, 2018.
  2. Duffy M. The Implantable Miniature Telescope (IMT) for End-Stage Age-Related Macular Degeneration. VisionAware. N.d. http://www.visionaware.org/info/your-eye-condition/age-related-macular-degeneration-amd/new-fda-approved-implantable-telescope-for-end-stage-amd/125. Accessed November 21, 2018.