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Does micropulse laser have a role in DME treatment in era of intravitreal injections?
Tatiana Queirós, MD, explains why she thinks research is important and discusses a study conducted at her ophthalmology department.
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Being involved in a research project is crucial to the development of critical thinking, which is the basis of clinical reasoning.
Tatiana Queirós is an ophthalmology resident at the Hospital de Braga in Portugal. She describes her experience of getting involved in a large research project early on in her career and shares some of her results.
Anthony P. Khawaja, MB, BS, MA (Cantab), MPhil, FRCOphth
Chair of the SOE Young Ophthalmologists committee
To enter the world of ophthalmology and commence the long journey we want to successfully pursue is challenging and enriching, but also frightening. Suddenly we are contemplating a whole new reality, a new dimension that is extremely rich and complex. Hard work, patience, dedication and effective learning strategies are needed to acquire both clinical knowledge and surgical skills to become an eye specialist.
Even before entering this new world, I felt a strong need to satisfy my scientific curiosity because I believe that being involved in a research project is crucial to the development of critical thinking, which is the basis of clinical reasoning. Of course, it is not an easy choice or path to follow; on the contrary, it is very challenging and time-consuming and certainly not easy to fit into the super-busy life of a resident. Nevertheless, looking on the bright side, I truly believe that it is the most beautiful way to enrich our knowledge of anatomy and physiology, clinical presentation, appropriate investigation and therapeutic management of pathologies we know very little about, except from our books.
Studying DME treatments
As a young ophthalmologist, it was a pleasure to be part of a pioneering study on diabetic macular edema, an increasingly prevalent condition that we are likely to encounter quite early in our clinical practice. As we know, DME is a major cause of visual loss in diabetic patients. Treatment encompasses lifestyle modifications, namely weight loss and exercise, as well as glycemic control. Current medical and surgical treatments include intravitreal injections of corticosteroids or anti-VEGFs, laser therapy and pars plana vitrectomy. Results from the Early Treatment Diabetic Retinopathy Study in 1985 showed reduction of moderate vision loss with laser treatment. After this, conventional laser became the gold standard for DME. Since then, anti-VEGF therapy has been tested, either alone or in association with laser treatment.
Combining anti-VEGF and laser treatments was based on the rationale that initial reduction of edema with an anti-VEGF agent would provide better baseline conditions for laser treatment, leading to more durable effects and fewer injections as compared with anti-VEGF therapy alone. However, long-term results showed that combination with laser treatment does not improve visual outcome as compared with anti-VEGF treatment alone. Furthermore, although conventional laser still remains the gold standard for DME, the risk for complications with laser, such as retinal burns with retinal pigment epithelium atrophy, is well known. In 2000, a new laser modality, micropulse laser, was for the first time applied with the intent of avoiding any visible damage (subthreshold photocoagulation). It is now believed that laser therapeutic efficacy does not necessarily imply the creation of retinal damage, but rather the direct inhibition of angiogenesis.
Study with 532 nm micropulse laser
Until recently, this low-intensity high-density technique used either a 577 nm or an 810 nm diode laser. To the best of our knowledge, our study was the first clinical study to use a 532 nm micropulse laser, a laser of higher power, better absorbed by melanin and hemoglobin but with poor absorption by the inner layers of the retina, thus protecting the neurosensory retina.
In order to evaluate the efficacy of this wavelength, we designed a retrospective study in our ophthalmology department at Hospital de Braga, Portugal. We used a 532 nm micropulse laser in patients with foveal DME with a maximum internal thickness of 250 µm as measured by OCT that was not suitable for conventional laser treatment (100 µm to 300 µm from the fovea) or nonresponsive to intravitreal therapy.
One hundred fifteen eyes of 84 patients with a mean age of 65 years were included. With regard to effectiveness, we achieved stabilization of visual acuity and a statistically significant decrease in the area of leakage on fluorescein angiography after laser treatment. In relation to the OCT data, we found a statistically significant decrease in the thickness of the treated area. Moreover, and equally important, no complications were reported. It was curious to find that naïve patients showed the most benefit, with time free of treatment being significantly longer compared with patients who underwent intravitreal injections alone or in combination with conventional laser.
The question remains: Is there a place for micropulse laser treatment in the era of intravitreal injections? Our study with the micropulse 532 nm laser demonstrated an effective and safe profile for the treatment of center-involved DME. However, additional studies are needed to further assess the benefits of this therapy in diabetic patients. We are developing a protocol for a prospective study in our department, in which metabolic parameters will also be taken into account.
In the near future, I hope to have an answer to this question for you.
- References:
- Das A, et al. Ophthalmology. 2015;doi:10.1016/j.ophtha.2015.03.024.
- Early Treatment Diabetic Retinopathy Study research group. Arch Ophthalmol. 1985;doi:10.1001/archopht.1985.01050120030015.
- For more information:
- Tatiana Queirós, MD, is an ophthalmology resident at Hospital de Braga, Portugal. She can be reached at email: tatiana.smq@gmail.com.
- SOE Young Ophthalmologists website: http://soevision.org/yo.
Disclosure: Queirós reports she has no relevant financial disclosures.