Laser stops, may partially reverse AMD

November 1, 2010

The idea to use a nanosecond laser-based treatment to impede the progress of age-related macular degeneration seems to have been fruitful.

The results of a pilot study of a non-thermal nanosecond laser therapy (Ellex Retinal Regeneration Therapy [Ellex 2RT], Ellex) indicated that of the 14 patients followed for 6 months after treatment, 10 have improved vision in the treated eye, said Robyn Guymer, MB BS, PhD, FRANZCO, who oversees the Macular Research Unit, Centre for Eye Research Australia, University of Melbourne, Royal, Victorian Eye and Ear Hospital, Melbourne, Australia.

Dr. Guymer and colleagues found that the laser therapy eliminated drusen in the treated eye and in so doing, the investigators hope to reverse the degenerative process of AMD and save patients' sight. The difference between this technology and currently available treatments for AMD is that this laser can be applied before patients actually lose vision. With most AMD treatments, the disease is not addressed until it has reached the late stage, when vision cannot be restored.

Twenty patients with bilateral high-risk early AMD were initially enrolled in the study and one eye of each patient was treated with one dose of energy using the laser. The fellow eye served as a control. The laser was applied in one session with 12 subthreshold 400-µm spots placed in a clock-hour distribution 1,400 µm from the fovea in one eye, Dr. Guymer explained.

To date, 14 patients have been followed out to 6 months. Of these, 10 patients had improved visual function or the drusen resolved. In some cases, the effect of the laser was not evident until 6 months after treatment. The parameters that showed improvement were dark adaptation, flicker, color thresholds, visual acuity, and drusen resolution.

A major advantage of this laser is that no retinal burns develop, which implies minimal damage to the retinal tissue.

"Of great interest, the 10 fellow eyes also improved in either visual function or drusen resolution," Dr. Guymer said.

This improvement was unexpected, she noted. The parameters that showed improvement in the fellow untreated eye were also dark adaptation, flicker, color thresholds, visual acuity, or drusen resolution.

Clearly, the laser is inducing some long-term systemic effect that is able to affect the contralateral eye, and we are currently working to investigate possible mechanisms that could cause this response, Dr. Guymer noted.

The investigators found that the greatest retinal dysfunction in the 14 patients was in the parafoveal area, where geographic atrophy usually starts, she said.

"In our first 14 patients, this area of greatest dysfunction improved in seven treated eyes and one fellow eye," she said.

Interestingly, the improvements in the retina were not related to the position of the laser spots nor necessarily where the drusen resolved.

According to the investigators, "it is anticipated that [the laser] will address at least one underlying process in AMD, reduced flux across Bruch's membrane. The laser design should enable the positive features of previous laser studies for early AMD to be harnessed without entertaining any of the negative effects such as neovascularization."

Reversing the drivers

Dr. Guymer said that the improvement that was seen in the area of the worst retinal dysfunction suggested that "the treatment may be reversing the drivers of the disease."

"A long-term, formal, randomized clinical trial is needed to determine if [the laser] does reduce the progression to vision loss in AMD, but the early results are very encouraging," Dr. Guymer said.

The investigators hope to treat a total of 50 patients in the 2-year pilot trial. The laser therapy also has shown promise for the treatment of diabetic macular edema.

FYI

Robyn Guymer, MB BS, PhD, FRANZCO
E-mail: rhg@unimelb.edu.au

Dr. Guymer has no financial interest in this technology. Study support was provided by Ellex Research & Development Pty Ltd. and the Victoria State Government.