Rheopheresis may be useful in dry AMD

Fort Lauderdale, FL-In a small open-label trial of rheopheresis therapy (RHEO, Occulogix) for the treatment of dry age-related macular degeneration (AMD), patients who did not have elevated levels of certain macromolecules demonstrated visual results similar to those of patients in a separate study who had significantly elevated levels of macromolecules such as fibrinogen, IgA, and total cholesterol.

Significantly, 16% of eyes (five of 30) in the more recent trial experienced improvement in vision and a decrease in drusen, said David T. Wong, MD, FRCSC, assistant professor of ophthalmology, department of ophthalmology, St. Michael's Hospital, University of Toronto, Ontario, Canada. He presented results from the Prospective Evaluation of Rheopheresis in Canada (PERC) study during the annual meeting of the Association for Research in Vision and Ophthalmology.

Medical science has little to offer patients with dry AMD except vitamin therapy to slow disease progression, but rheopheresis could change that, Dr. Wong said.

Rheopheresis is a blood-filtration process to remove certain plasma proteins and lipoproteins that contribute to AMD. These proteins and fats are thought to reduce microcirculation including blood circulation in the retina.

The 12-month, single-center, open-label PERC trial enrolled 30 eyes of 20 patients with documented evidence of dry AMD. Each patient received a series of eight rheopheresis treatments over a 10- to 12-week period; clinical data were gathered at 3-month intervals for a year following the initial treatments.

Six-month follow-up results of this trial were compared with interim results of a multicenter, double-masked, placebo-controlled (sham apheresis) trial, MIRA-1 (Multicenter Investigation of Rheopheresis for AMD), in which 180 subjects who had late-stage, high-risk AMD were enrolled. These subjects demonstrated elevated plasma levels of select hemorheologic macromolecules in their blood.

In MIRA-1 and all other previous studies of rheopheresis in dry AMD, patients had to have elevated levels of the blood markers.

"One of the questions I had was: 'Do they really need to have elevated levels of the macromolecules to get the response from the rheopheresis?' " Dr. Wong said. "The earlier trials suggested that patients really needed the elevated macromolecule levels to have an improvement, but there was some evidence that it may not have been necessary."

Thus, inclusion criteria for PERC did not include elevated macromolecule levels. In other respects, inclusion criteria were similar to those of the MIRA-1 study. Patients were required to have dry AMD in the study eye, at least 10 large, confluent drusen more than 125 µm in size, and vision from 20/32 to 20/100.

Exclusion criteria included wet AMD, any other retinal diseases, glaucoma, and geographic atrophy within 500 µm of the center of the fovea.

The mean age of patients was about 70; all were receiving AREDS vitamin therapy and were nonsmokers.

Tests performed during the study included ETDRS best-corrected visual acuity (BCVA), fundus evaluation, fluorescein angiography, digital color photography, optical coherence tomography, and contrast sensitivity.

Results showed several similarities between the PERC and MIRA-1 studies, despite the difference between the patient groups in the level of macromolecules, as well as some unexpected findings.

Drusen disappearance

"What was really interesting about the whole thing was that we found that five eyes out of the 30 had significant disappearance of the drusen with a gain in vision, which is essentially unheard of," Dr. Wong said. "When you look at the natural population, that is a really high number, and that is what was fascinating to us."

The rapid disappearance of the drusen, over the course of 12 months, was also encouraging, he added.

Investigators are unsure why the dramatic decrease of drusen and improvement in vision occurred in this subgroup of patients in the PERC study and are further analyzing the data.