Laser Reduces Retreatment in Diabetic Macular Edema

Damian McNamara

October 02, 2013

HAMBURG, Germany — The combination of laser therapy plus ranibizumab (Lucentis, Novartis, Genentech) leads to significantly fewer injections for patients with diabetic macular edema than treatment with ranibizumab alone, according to a prospective study.

"The laser is still alive. We got good visual results," Marcus Kernt, MD, from the Ludwig Maximilians University in Munich, told Medscape Medical News.

In addition to reducing the use of vascular endothelial growth-factor (VEGF) inhibitors, "we might also get greater improvement in vision for a patient," he added. The combination led to a nonsignificant trend toward better visual acuity.

Dr. Kernt presented 12-month study results here at the 13th EURETINA Congress.

Vision and optical coherence tomography thickness were similar in the combination and monotherapy groups. However, with the combination, "the retreatment rates are significantly reduced — by more than 50% — and postupload injections are reduced by more than 75%," Dr. Kernt reported.

In previous trials of patients with diabetic macular edema, VEGF inhibitors were credited with an average visual improvement of 6 to 10 letters, Dr. Kernt said. However, patients in these studies generally required 7 to 12 injections in the first year to realize these gains. "This is a significant burden for patients and doctors," he noted.

 
What was significantly different was that 65% of the combination group did not need retreatment for 1 year.
 

The search to find a potential solution drove Dr. Kernt and his team to consider the Navilas navigated photocoagulation laser system (OD-OS, Inc). It has been demonstrated that the Navilas system has a "stabilizing effect on vision without requiring too many retreatments," he explained.

Although in previous studies conventional lasers have shown no additional benefit when combined with a ranibizumab regimen, Dr. Kernt theorized the navigated laser might make a difference.

After 66 patients with diabetic macular edema received a loading phase of 3 monthly ranibizumab injections, they were assigned to receive either combination treatment with navigated laser therapy plus ranibizumab (n = 34) or ranibizumab monotherapy (n = 32).

In both groups, central retinal thickness decreased significantly from baseline and visual acuity significantly improved. There was no significant difference between the 2 groups in central retinal thickness or visual acuity.

"What was significantly different was that 65% of the combination group did not need retreatment for 1 year, compared with 16% of the monotherapy group," Dr. Kernt said.

Table. Outcome at 12 Months

Outcome Combination Group Monotherapy Group
Mean visual acuity gain 8.4 letters 6.3 letters
Gain of ≥10 letters 47% 31%
Gain of ≥15 letters 21% 9%

 

In the year after the initial upload phase, the mean number of injections was significantly lower in the combination group than in the monotherapy group (0.9 vs 3.9; P ≤ .001).

Dr. Kernt explained that the concept behind the combination therapy is to flatten the retina with the 3 ranibizumab injections and then use the navigated laser to promote long-term stabilization of the results.

The navigated laser has the advantage of providing full retinal imaging in color, infrared imaging, and an ability to use the imaging to do digital treatment planning. "You can then apply treatment semi-automatically on the patient, which results in a high amount of safety and precision," he noted.

"It is an interesting approach. If it helps to reduce the number of injections, it can decrease the burden for patients," said Lars Wagenfeld, MD, from the Department of Ophthalmology at Universitatsklinikum Hamburg-Eppendorf in Germany, who was asked to comment by Medscape Medical News.

However, he added, "the problem at this time is that the navigated laser is not widely distributed, and it is very expensive." The navigated laser costs about $200,000, whereas a conventional laser costs from $13,500 to $27,000, he reported.

One audience member asked Dr. Kernt if the same results are possible for ophthalmologists who do not have access to the navigated laser.

"So far, no advantage of conventional lasers has been shown in other trials," he replied. "If you are very good you might have comparable results. However, the navigated laser adds a very high degree of precision."

Another audience member asked how the laser is targeted if the retina is sufficiently flattened by the 3 ranibizumab injections. Dr. Kernt replied that data collected both before and after the loading phase are used to guide the laser treatment.

"Your study has a very intelligent design," said session moderator Heinrich Gerding, MD, from the Department of Ophthalmology at Pallas Clinic Olten in Switzerland.

"It's good you deferred the laser until 3 months after the beginning of the study, which probably means more effect with less energy. For me, this is the best information from your study — that deferred laser treatment is very effective and, in combination with anti-VEGF treatment, gives the best results," he said.

OD-OS supplied the laser used in the study. Dr. Kernt and Dr. Wagenfeld have disclosed no relevant financial relationships.

13th EURETINA Congress. Presented September 29, 2013.

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