Navigated laser for DME reduces anti-VEGF re-treatment rate

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Photocoagulation with a navigated laser is safe and significantly reduces the need for further anti-vascular endothelial growth factor injections in patients with diabetic macular edema.

Dr. Kernt

By Cheryl Guttman Krader; Reviewed by Marcus Kernt, MD

Munich-The addition of navigated laser (Navilas Navigated Laser System, OD-OS) photocoagulation to anti-vascular endothelial growth factor (VEGF) therapy is a promising approach for treating diabetic macular edema (DME).

The treatment dramatically reduces the burden of intravitreal injections, according to results from 12 months of follow-up in the prospective CAVNAV study, said Marcus Kernt, MD.

“Anti-VEGF treatment has become a valuable option for improving vision in eyes with DME, and we were very happy when ranibizumab [Lucentis, Genentech/Novartis] was approved for this indication in Germany 2 years ago,” said Dr. Kernt, Department of Ophthalmology, Ludwig-Maximilians-University, Munich, Germany, and an investigator in the study. “However, we all know that the price for this benefit is the need for continuous injections.”

About the study

The study enrolled 66 patients with center-involving DME who were divided into combination treatment and anti-VEGF monotherapy groups. All patients received ranibizumab given as 3 monthly injections (loading phase) followed by as needed (p.r.n.) treatment based on pre-specified criteria.

In the combination group, patients underwent navigated laser treatment following the third anti-VEGF injection. The laser treatment was administered using a modified grid approach that combined focal treatment of microaneurysms with grid treatment in areas of diffuse macular edema.

Patients returned for monthly follow-up and received a ranibizumab injection if spectral-domain optical coherence tomography showed a >20% increase in central retinal thickness and/or the patient had a >6 letter loss from best best-corrected visual acuity (BCVA).

The two study groups were similar with respect to demographic characteristics, as well as BCVA and central retinal thickness at baseline. At the end of 12 months, the combination group had a significantly lower anti-VEGF re-treatment rate than the monotherapy group (35% versus 84%) and received significantly fewer p.r.n. injections (0.9 versus 3.9).

Median time to re-treatment was 63 days in the ranibizumab monotherapy group, but had not yet been reached in the combination group with follow-up exceeding 300 days.

Anatomic and functional outcomes were similar in the two groups at 12 months, although there was a trend for better visual acuity gains in eyes receiving combination therapy. Mean central retinal thickness was reduced from 441 µm at baseline to 313 µm in the combination treatment group and from 444 to 339 µm in patients receiving ranibizumab monotherapy. Mean change from baseline BCVA in the two groups was 8.4 letters and 6.3 letters, respectively, and the proportions of patients achieving a 10- or 15-letter gain in BCVA were also higher in the combination treatment group.

What the research means

“The results from 12 months of follow-up in the CAVNAV study are very encouraging,” Dr. Kernt said. “They show use of the navigated laser is associated with greater benefit for reducing the need for anti-VEGF reinjections when compared with results from previously reported studies investigating conventional laser photocoagulation combined with anti-VEGF treatment.

“In addition, they are highly consistent with data from the U.S.-based CAVNAV study where bevacizumab (Avastin, Genentech) is being used instead of ranibizumab,” he said. “Now, we look forward to outcomes from longer follow-up and from a multicenter randomized trial now under way in the United States.”

The latter study (known as the TREX-DME study), is a phase I/II open label study with a planned recruitment of 150 patients in which patients are receiving ranibizumab 0.3 mg monthly or in a treat-and-extend protocol with or without navigated laser photocoagulation of microaneurysms. Planned duration is 24 months.

Novel photocoagulator

The navigated laser platform is a scanning slit-based instrument that integrates digital imaging capabilities with a 532-nm laser photocoagulator. It allows digital treatment pre-planning and provides real-time registration between the diagnostic images, treatment plan, and live retinal image to guide precise laser spot delivery for improved efficacy and safety.

The treatment is performed without the need for a contact lens, making it more comfortable for patients, and data show that it is better tolerated and associated with better results.

“We had the opportunity to be involved in early studies with the navigated laser system, and the outcomes of that research showed the laser delivered 96% of treatment spots within 100 µm of target,” he said. “In addition, we found it was associated with significantly less pain during treatment compared with conventional focal macular laser photocoagulation.”

Most importantly, however, analyses of data from propensity score matched groups of patients showed patients treated for DME with the navigated laser (as opposed to conventional laser) had better visual acuity outcomes with fewer laser re-treatments during 8 months of follow-up, Dr. Kernt concluded.

Marcus Kernt, MD

E: marcus.kernt@med.uni-muenchen.de

Dr. Kernt is a lecturer for Allergan, Bayer, Novartis, Pfizer, OD-OS, and Optos, and a consultant to OD-OS and Optos.

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