Nancy A. Melville

May 12, 2014

ORLANDO, Florida — Patients with posterior vitreous detachment (PVD) require fewer intravitreal injections of the vascular endothelial growth-factor (VEGF) inhibitor ranibizumab when being treated for neovascular age-related macular degeneration, according to new research.

"Although some retrospective studies have supported the theory, this is the first prospective study to confirm that this is indeed a trend," said lead author Lisa Faia, MD, from the Oakland University William Beaumont School of Medicine in Rochester, Minnesota.

She presented the findings here at the Association for Research in Vision and Ophthalmology 2014 Annual Meeting.

Dr. Faia and her colleagues evaluated 33 patients with age-related macular degeneration who were treated with ranibizumab 0.5 mg each month for 3 months, and then as needed.

At baseline, 18 patients had PVD, determined with B-scan ultrasonography and spectral domain optical coherence tomography. There were no differences in sex, age, or eye involved between those with and those without PVD.

The average number of injections was higher in the non-PVD group than in the PVD group (9.44 vs 8.40; P > .05), and the odds of requiring at least 1 injection was 2.05 times higher in the non-PVD group.

In the non-PVD group, the odds of requiring at least 1 injection in months 5 to 8 of the study was 1.30 times higher than in months 9 to 12 (95 % confidence interval, 0.327 - 4.923).

Six-month scans showed that 4 of 15 (26.7%) patients in the non-PVD group had developed PVD. At baseline, 54.5% of patients had PVD; this increased to 66.7% at 1 year.

This is consistent with what is commonly observed for the development of PVD after anti-VEGF injections, Dr. Faia said.

"Just doing the injections alone can give you a rate as high as 10%. This finding supports that," she told Medscape Medical News.

Animal studies have shown a slower rate of retinal penetration with bevacizumab injections when the vitreous is attached to the anterior retinal surface. This suggests that PVD gives the drug a more direct route of delivery, so fewer injections can be just as effective, Dr. Faia explained.

"We have shown that having PVD can give the drug better access to the retina, and there still is the vitreous reservoir to keep some of the drug around, so you have a longer effect," she added.

Ultimately, this could help identify which patients will respond to treatments, and spare them unnecessary injections.

"Larger studies are needed, but I think it would be better for patients if, overall, they required fewer injections," Dr. Faia said.

The effect of PVD on anti-VEGF injections "is something we've thought about theoretically for a long time," said Rishi Singh, MD, medical director of the clinical systems office at the Cleveland Clinic and assistant professor of ophthalmology at Case Western Reserve University.

"It appears to makes sense from a pathophysiologic level, and it's something we've seen before with our own patients," he told Medscape Medical News. "I am quite impressed with the data."

The study received research support from Genentech. Dr. Faia has disclosed no relevant financial relationships. One of the study coauthors, Michael T. Trese, has been a consultant for Genentech. Dr. Singh reports being a consultant for Alcon, Thrombogenics, Regeneron, and Genentech

Association for Research in Vision and Ophthalmology (ARVO) 2014 Annual Meeting: Abstract 589. Presented May 4, 2014.

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