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Laser treatment a safe alternative to medical treatment of DME
Laser photocoagulation continues to play an important role.
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While anti-VEGF therapy has proven to be an exciting therapy for diabetic macular edema, studies to date support a continued role for laser photocoagulation therapy in primary, combination and salvage scenarios.
In patients with only modest central retinal thickening, who may represent 20% to 30% of cases, laser therapy has been demonstrated to be equivalent to anti-VEGF therapy. Furthermore, the European Public Assessment Report for Lucentis (ranibizumab, Genentech) from the European Medicines Agency has not recommended the use of anti-VEGF treatment in this population.
In addition, the approximately 30% to 35% of patients who do not demonstrate a benefit from repeated anti-VEGF therapy may still benefit from laser therapy as a salvage therapy.
Finally, while some combination treatment strategies have not shown any added benefit of laser therapy, several studies suggest that alternative combination protocols may reduce the requirements for repeated intravitreal injections.
Recent advances
While these findings have been made with standard laser therapy, advances in laser application technology may further solidify the continued role for laser therapy in diabetic macular edema and other retinal conditions. Even though there is wide variability in how laser therapy is currently applied, a modified ETDRS treatment that combines focal closure of microaneurysms with light grid laser for areas of edema and/or non-perfusion has demonstrated superiority to conventional grid laser, suggesting the clinical value of more precise treatment targeting.
More recently, laser technology has been further optimized with the development of so-called navigated retinal photocoagulation, which integrates fluorescein imaging, image stabilization and tracking with a 532-nm laser (Navilas, OD-OS). The surgeon utilizes a computer screen to mark planned treatment locations on a fluorescein or color image. The treatment plan is then registered to the live fundus image of the retina, facilitating more precise positioning of laser spots. The precise placement of the laser allows lower total energy delivery, with the potential for less collateral damage. The treatment does not require use of a contact lens or topical anesthesia, increasing comfort for both the physician and the patient, while also providing an electronic record of individual treatment locations and parameters.
The following cases support the continued importance of laser photocoagulation in treating diabetic macular edema.
Stephanie Lu
Case 1
A 50-year-old man with diabetic retinopathy and diabetic macular edema refractory to three serial injections of Avastin (bevacizumab, Genentech) underwent focal laser therapy using the Navilas navigated laser. Fluorescein angiography performed before the laser procedure revealed a superior leaking microaneurysm very close to the fovea. Optical coherence tomography with the Cirrus (Carl Zeiss Meditec) performed before the Navilas laser procedure showed a central retinal thickness of 529 µm, which decreased to 335 µm 6 weeks after the procedure. At 12 weeks after laser therapy, central retinal thickness showed a further decrease to 305 µm and recovery of the foveal depression. Overall, the patient’s visual acuity improved five letters. Navilas documented the treated spots and laser parameters used during the procedure.
Case 2
A 47-year-old woman with severe nonproliferative diabetic retinopathy and clinically significant macular edema showed worsening of visual acuity in the left eye over the previous 5 months. Fluorescein angiography revealed a focal area of leakage very close to the superior fovea that was treated with a total of 29 spots using the Navilas laser. Optical coherence tomography performed before the Navilas laser procedure showed a moderately increased central retinal thickness of 363 µm that decreased to 291 µm by 4 weeks after the procedure. Visual acuity improved eight letters. No anti-VEGF treatment was applied or required.
Advantages of laser therapy
These cases demonstrate the continued importance of laser therapy in the treatment arsenal for diabetic macular edema. Furthermore, we are currently evaluating the potential for more precise treatment using Navilas in eyes that have responded to previous anti-VEGF therapy.
In addition to offering the potential for reducing the number of intravitreal injections, Navilas therapy also has advantages in academic and teaching environments. Attending ophthalmologists and trainees can create treatment plans together, which represent a blueprint for proposed laser treatment. Trainees are then able to carry out the treatment plan exactly as drawn under direct supervision, making focal photocoagulation a safe procedure during training. Furthermore, notations can be placed on the treatment plan to avoid laser burns in specific areas, which is particularly important when treating very close to the fovea.
Taken together, these findings support an important role for navigated retinal therapy in various diabetic macular edema scenarios. Application to other central and peripheral retinal diseases is also being evaluated and will likely provide additional advantages.