Risk factors predict geographic atrophy after anti-VEGF treatment of RAP

By Lucy Piper, Senior medwireNews Reporter

Researchers have found three factors that could identify which patients with retinal angiomatous proliferation (RAP) receiving anti-vascular endothelial growth factor (VEGF) treatment are likely to develop geographic atrophy (GA).

“VEGF plays an important role in the maintenance of the choriocapillaris by the [retinal pigment epithelium]”, explain the researchers, “therapies that block VEGF could have an effect on the development and progression of GA.”

They studied a total of 43 eyes in 38 patients that were diagnosed with RAP and were treated with an initial loading dose of three intravitreal injections of the anti-VEGF ranibizumab at 1-month intervals, followed by additional injections as required.

At the end of 2 years of follow-up, the patients had received an average of 7.52 injections and GA had developed in 16 (37.2%) eyes.

Stepwise regression analysis showed that GA development was significantly associated with a thinner subfoveal choroid on spectral-domain optical coherence tomography images, evidence of reticular pseudodrusen and the presence of GA in the fellow eye at baseline.

Given that the first two of these factors are more characteristic of RAP in comparison with typical neovascular age-related macular degeneration (AMD), the researchers, led by Han Joo Cho (Konyang University College of Medicine, Seoul, South Korea), suggest such disease characteristics may increase vulnerability to atrophic changes and GA development.

By contrast, GA development was not significantly associated with the number of ranibizumab injections received, a possibility previously raised when using a monthly injection regimen versus a pro re nata regimen. The team suggests in the American Journal of Ophthalmology that the lack of association may be due to a low overall injection number in their study because of the “as needed” follow-up injection protocol.

But despite this, the incidence of GA development was higher than in previous studies on neovascular AMD, the researchers comment. Therefore monthly injection treatment “should be performed cautiously” in RAP patients, particularly if they have any of the three risk factors, they advise.

The team concludes: “These findings may be useful to clinicians using intravitreal anti-VEGF for the treatment of RAP, both for selecting an appropriate treatment plan and for predicting GA development.”

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