Visual prosthetic implant improves vision in patients with end-stage AMD

March 1, 2007
Lynda Charters

Las Vegas-Two-year results of a study of a visual prosthetic device (Implantable Miniature Telescope [IMT], developed by Isaac Lipshitz, MD, VisionCare Ophthalmic Technologies Inc.) indicate that the device improves visual acuity and the quality of life in patients with end-stage age-related macular degeneration (AMD). Few retinal complications were associated with the implantation of this device, according to Paul Sternberg Jr., MD, who spoke here at the American Academy of Ophthalmology annual meeting.

When the implant was reviewed by an FDA panel in July, recommendation for approval was not granted based on the agency's request for additional data. Dr. Sternberg focused his presentation on the 2-year results with emphasis on the additional data requested by the FDA. Dr. Sternberg is the G.W. Hale Professor and chairman, Vanderbilt Eye Institute, Vanderbilt University School of Medicine, Nashville.

"The [device] is intended for individuals with bilateral irreversible AMD for whom there are currently no beneficial treatments," Dr. Sternberg said, adding that 60,000 to 80,000 Americans fall into this category.

In the phase II/III IMT-002 trial, 217 patients with end-stage AMD participated at 28 clinical sites and were followed by a retina specialist, an anterior segment surgeon, and a rehabilitation specialist. The study outcome measures included an improvement of 2 or more lines of vision in distance or near visual acuity, improved quality of life, limited endothelial cell loss, and preservation of the baseline visual acuity. Of the 217 patients, 206 underwent successful implantation of the device.

"From the safety perspective, the baseline vision was preserved. However, the percentage of endothelial cell density loss exceeded the study target," he said.

The 2-year results showed that the visual acuity outcomes were similar to those at 1 year. At 2 years, the mean distance best-corrected visual acuity (BCVA) improved 3.2 lines and the mean near BCVA improved 2.9 lines. A gain of 3 or more lines of distance BCVA occurred in 59.2% of the eyes with implants compared with 10.3% of the control fellow eyes (p <0.0001).

"There was only an additional 2.5% loss of corneal endothelial cells at the 2-year time point. The substantial gain in visual acuity that was seen in some patients appeared to be due to dramatic changes in the size and character of the patients' central scotoma," Dr. Sternberg noted. "It is striking to compare the postoperative view with the [implant] with the view seen through an external-telescope eye spectacle."

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