New laser treatment helps to reduce the rate of progression of age related macular degeneration (AMD)
Age related macular degeneration (AMD) is the leading cause of irreversible vision loss in industrialized nations and costs the Australian economy in excess of $2.5 billion per year. The recent development of the nanosecond laser (2RT, Ellex, Pty Ltd) offers great promise as a treatment that may reduce progression of the disease. The results of a recent Australian clinical trial show a four-fold reduction in the rate of progression to late stage AMD in 76% of intermediate AMD patients who received Ellex 2RT laser treatment over the three years of the study. The Laser intervention in Early stages of Age Related Macular Degeneration (LEAD) trial was a multicentre clinical trial that evaluated whether nanosecond laser treatment of patients with intermediate AMD could reduce progression to advanced disease.
One of the principal investigators in the study, Professor Erica Fletcher from the Department of Anatomy and Neuroscience at the University of Melbourne, states that drusen (deposits which contain cellular fragments and an accumulation of basal laminar material) are an important early feature of AMD, whose size is predictive of the risk of progression. Methods of treating eyes with drusen as a means for reducing progression of AMD have been investigated over the last few decades. While many studies have shown a reduction in drusen in response to laser therapy, unfortunately this treatment also often caused significant damage to the neural retina. Ellex 2RT is a non-thermal nanosecond laser therapy which stimulates a natural, biological healing response in the eye and works by selectively targeting the retinal pigment epithelium (RPE) with single three nanosecond pulses. Professor Fletcher goes on to point out that owing to its short pulse length, the amount of energy absorbed within the RPE is less than 0.5% of that of a continuous wave laser, and thus there is little if any “thermal” damage of cellular tissue including the adjacent retina or choroid with this treatment.
The study, which was published in the journal Ophthalmology, says the presence of reticular pseudodrusen (RPD) is a key biomarker of retinal pigment epithelium (RPE) dysfunction and has a high association with progression to late-stage AMD. Unlike conventional drusen deposits, which are located between the RPE and Bruch’s membrane, RPD – which are likely to be of different aetiology – are located above the RPE and are often associated with late AMD. Professor Fletcher states that intervention with Ellex 2RT in patients who did not have coexistent reticular pseudodrusen (RPD) at the start of the trial resulted in a significant treatment effect and a clinical meaningful reduction in the rate of progression from intermediate to late stage AMD. However, in participants where baseline RPD were present, there was an increased rate of progression to late AMD in the Ellex 2RT treatment group compared to the group which underwent the placebo treatment. Professor Fletcher postulates that it is possible that RPD develop as a consequence of an unhealthy RPE and represent a further advancement in RPE pathology beyond what is associated with conventional drusen. It is possible, that in those with RPD, the RPE is so unhealthy that a laser treatment that selectively ablates RPE simply adds to the already sick and dying RPE, hastening the progression of disease. In summary, the use of nanosecond laser for treating patients with intermediate AMD shows some promising results for reducing progression of disease especially in those with conventional drusen.