Telescopic implant improved vision in AMD, but endothelial cell loss a concern

A telescopic IOL improved vision in patients with bilateral end-stage age-related macular degeneration in a phase 3 trial. However, the rate of endothelial cell loss exceeded the primary safety endpoint, investigators said.

The study, which is published in the November issue of Ophthalmology, found that eyes implanted with the device had a mean reduction in endothelial cell density of 20% at 3 months and 25% at 1 year after implantation. This exceeded the 17% reduction specified as the primary safety endpoint in the study protocol.

Concerns over safety and efficacy of the Implantable Miniature Telescope (IMT, VisionCare Ophthalmic Technologies Inc.) resulted in the Food and Drug Administration's ophthalmic devices advisory panel recommending against its approval in July.

In a press release from VisionCare announcing the publication of the study, one of the trial's investigators said, "We believe that corneal health was maintained," despite the loss of endothelial cells during surgery.

"There was a significant correlation between postoperative cell loss and the level of corneal edema on the first postoperative day. Therefore, it appears that the majority of cell loss was due to the impact of the surgical procedure," said Stephen S. Lane, MD, the trial's medical monitor, in the release. "Stabilization of cell density 3 to 12 months after surgery was consistent with what we'd expect after large-incision intraocular surgery. While the techniques required to implant the device are well within the skill set of anterior segment surgeons, a surgeon training program will be utilized to address the risk of acute endothelial cell density loss during implant."

In the phase 3 trial, first author Henry L. Hudson, MD, and colleagues prospectively studied the outcomes 206 eyes of 206 AMD patients who underwent phacoemulsification and were implanted with the IMT. Contralateral eyes, which were not treated, served as controls. All patients preoperatively had a moderate to profound loss of bilateral central visual acuity as a result of untreatable geographic atrophy, disciform scars, or both, according to the study.

At 1 year, 67% of implanted eyes improved by three or more lines in best corrected distance visual acuity (BCDVA), compared to 13% of control eyes (P < .0001). In addition, 53% of implanted eyes improved three or more lines in both best corrected near and distance visual acuity vs. 10% of control eyes (P < .0001), according to the study.

Quality-of-life survey scores also significantly improved from baseline (P < .01) on seven of eight relevant subscales, the authors said.

VisionCare officials said they hope to submit a response to the FDA in the first quarter of 2007 regarding "deficiencies in the application that must be addressed to place the regulatory submission in approvable form." If no additional analyses or clinical data are required, the company projected regulatory approval in the second half of 2007, according to the release.