Evidence Review: Lasers for PDR

Download PDF

Since the early treatment of Diabetic Retinopathy Study (ETDRS), argon laser photocoagulation has been the gold standard for treating prolif­erative diabetic retinopathy (PDR). And, in recent years, there have been attempts to modify the technique and introduce new laser technologies. But do these strategies provide safe and effective alternatives? A team from the United Kingdom reviewed the litera­ture and found a significant gap in the evidence.¹

Intervention review. To assess the effects of different lasers and different laser protocols, the U.K. researchers identified and evaluated 11 randomized controlled trials proposing alternative laser modalities for the treatment of PDR. These trials compared a variety of modifications to the ETDRS standard of care, including different laser types, a variety of pulse intensities and dura­tions, and altered scatter distributions for laser burns.

“After assessing and grading the overall certainty of the results, we found that these trials provide limited evidence with respect to the efficacy and safety of alternative laser systems or strategies,” said Tanya Moutray, MB BCh, BAO, FRCOphth. In particular, the review found, the trials were small in size, poorly conducted, and poorly reported. They also contained a high risk of bias and failed to clearly define study outcomes.

Potential for confusion. The ETDRS standard of care calls for a single-spot treatment—specifically, an initial treatment of midperipheral scatter laser consisting of 1,200 to 1,600 burns, 200- to 500-μm spot size, and an argon pulse duration of 100-200 ms with power titrated to produce moderate-intensity burns.

However, guidelines set by the Royal College of Ophthalmologists (RCO) contradict this standard, stating that “technological advances in new laser technology using multispot and micropulse abilities have widened clinical knowledge and treatment options.”² Dr. Moutray voiced concern regarding the RCO guidelines, noting that “our review was unable to find evidence to definitively support these alternative modalities.”

Advancing the discus­sion. Even so, physicians and clinicians should not ignore newer photocoagu­lation strategies because of the quality of these trials, said Dr. Moutray. Instead, she said, she hopes that her team’s work will set a frame­work for future research.

“New clinical trials focusing on PDR management and modern laser thera­pies can build on the research by using our findings and recommendations. This will help avoid research waste and encourage researchers to conduct studies that are large enough to provide definitive answers and evaluate the long-term outcomes most relevant to patients,” she said.

—Mike Mott

___________________________

1 Moutray T et al. Cochrane Database Syst Rev. 2018;3:CD012314. doi:10.1002/14651858.CD012314.pub2.

2 https://www.rcophth.ac.uk/wp-content/uploads/2014/12/2013-SCI-301-FINAL-DR-GUIDELINES-DEC-2012-updated-July-2013.pdf. Accessed April 17, 2018.

___________________________

Relevant financial disclosures—Dr. Moutray: None.

For full disclosures and the disclosure key, see below.

• Microglia Can Repopulate Retinas After Depletion

• Measuring Intracranial Pressure: Is Ultrasound Acceptable?

• Visual Symptoms in Diplomats Posted to Cuba