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Laser advances take retina specialty to new levels of treatment, care
Developments in lasers, along with genetic engineering, are showing promise as technologies that may shape the future of retina treatment.
Take-home message: Developments in lasers, along with genetic engineering, are showing promise as technologies are may shape the future of retina treatment.
By Lynda Charters; Reviewed by Pravin U. Dugel, MD, and Michael S. Ip, MD
Innovation in laser treatment was tapped as one of the most exciting developments for the specialty of retina in 2014.
“Although lasers are now used less often to treat diabetic macular edema and age-related macular degeneration (AMD), there are some developments that are ongoing in laser technology that may redefine how we view laser treatment,” said Pravin U. Dugel, MD.
Some new laser technology may be so precise as to preclude destruction of photoreceptor cells but only stimulate retinal pigment epithelial (RPE) cells. There is also technology, such as the Navilas Laser System from OD-OS GmbH, that has superb registration and navigation capabilities, said Dr. Dugel, managing partner, Retinal Consultants of Arizona, Phoenix and clinical professor of ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles.
More in this issue: Instrumentation, imaging advances make retina surgery safer
Though laser treatment is not a thing of the past, Dr. Dugel believes the traditional way of performing laser procedures-i.e., simple destruction of tissue based on what can be seen-may be phasing out.
“In the near future, we will have extraordinary precision and navigation capabilities in our abilities to deliver very precise laser beams not to destroy tissue but possibly to stimulate RPE cells in specific areas of tissue to regenerate layers of retinal cells,” he said.
Genetic engineering
Both Dr. Dugel and Michael Ip, MD, associate professor, Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, are impressed with new gene-based therapies.
“In this technology, vectors are implanted to introduce genetic material into the eye to address specific diseases,” Dr. Ip said. “These can be placed in the intravitreal or subretinal space and are good potential avenues to regenerate tissue that has been destroyed by a variety of diseases.”
Dr. Dugel also pointed to new forms of genetic engineering that were studied during 2014. Genzyme and Avalanche Biotechnologies have developed two different approaches to genetic engineering for wet AMD using implanted viral vectors that can deliver an anti-vascular endothelial growth factor (VEGF) agent to correct disease processes.
Using the Genzyme strategy, the vector is injected into the mid-vitreous to access the back of the eye under the fovea. The approach used with the Avalanche Biotechnologies device is more direct, according to Dr. Dugel, in that the genetically engineered product is placed under the fovea during surgery.
Encapsulated Cell Technology is another form of genetic engineering being developed by Neurotech. This approach facilitates delivery of drugs into the vitreous. Two candidates, NT-503 and NT-501, are notable. The former is designed to treat wet AMD by delivering a drug into the eye with the goal of providing constant tissue exposure for more than 18 months. In both, genetically engineered drugs are encapsulated in a barrier and placed in the eye. This approach is being evaluated in clinical trials to treat dry AMD, retinitis pigmentosa, and macular telangiectasia.
Artificial retina
The success of the Argus II Retinal Prosthesis System (Second Sight Medical Products) is another achievement of the past year. The device received FDA approval in 2013, and the first successful implantations were performed at the Kellogg Eye Center of the University of Michigan, Ann Arbor, early in 2014. Both patients had retinitis pigmentosa.
“Implantation of this device is very promising, because it may allow patients to have better quality of life if they are able to perform activities of daily living,” Dr. Ip said. “In future years, we can look forward to further refinements of the technology. The system is a viable approach to an artificial retina.”
While tremendous growth has been seen over the past decade in the development of new treatment strategies for AMD, the upcoming decade may hold even more promise, according to Dr. Dugel.
“Stem cell technology is advancing rapidly, and it is possible that we will be able to take a skin sample from a patient with AMD and create a self-renewing line of healthy RPE and photoreceptor cells for subretinal transplantation and restoration of visual function,” he said.
Stem cell therapy could be implemented in the treatment of atrophic AMD primarily in two ways:
- To rescue diseased retinal cells by secretion of growth and neuroprotective factors and,
- To replace dead cells by transplantation and functional integration into host tissue.
It also may be used to treat exudative AMD after stabilization of choroidal neovascularization with anti-VEGF therapy.
Submacular surgery also may be re-introduced to treat exudative AMD. Stem cell-derived RPE and photoreceptor transplants would theoretically be able to “fill-in” the RPE and photoreceptor defects generated by the surgery, assuming the difficulties associated with synaptic integration can be overcome, he explained.
“Although many challenges still need to be overcome before stem cell therapy can benefit our patients with AMD, significant advances have recently been achieved,” Dr. Dugel said.
Human clinical trials are under way for stem cell-mediated treatment of Stargardt’s macular dystrophy, and similar trials for AMD are just around the corner, he said.
Pravin U. Dugel, MD
Dr. Dugel is a consultant to Acucela, Alcon Laboratories, Alimera, Allergan, Genentech, and Novartis, and is a consultant to and a minor shareholder in Aerpio and Ophthotech.
Michael S. Ip, MD
Dr. Ip has no financial interest in any aspect of this report.
