A New Era in Retinal Research

Retinitis Pigmentosa

Retinitis PigmentosaThe most common hereditary retinal dystrophy in the world is Retinitis Pigmentosa (RP). Over the past four years, the Department of Ophthalmology at the University of Pittsburgh School of Medicine, under the leadership of Dr. José -Alain Sahel, who has dedicated his career to the study and development of new treatments for hereditary retinal dystrophies, has placed Pitt at the forefront of research for RP around the world. Now, thanks in part to generous Eye & Ear Foundation donors such as Mr. Martin McGuinn, who established the Martin McGuinn Retina Research Fellowship, incredible progress is being made towards developing new treatment options for this disorder. The first McGuinn fellow, Boris Rosin MD, PhD is involved in all the innovative efforts conducted by the Department.

What is Retinitis Pigmentosa?

RP is a progressive disorder causing worsening visual impairment up to the level of legal blindness over the course of a patient’s lifetime. The term RP is used to encompass a large number of genetic disorders, which, while having a heterogenic genetic basis, share the same clinical appearance. This appearance includes pallor of the optic nerve, attenuation of the retinal blood vessels (specifically vessel narrowing), and a particular pattern of pigment deposition in the periphery of the retina, termed bone-spicule like pigmentation (due to its resemblance to histological preparations of bone tissue).

The most common forms of RP first affect the rod photoreceptors, which are responsible for night and peripheral vision. The initial symptoms of the disease are, therefore, usually night blindness and visual field restriction. As the disease progresses, central vision is also affected, leading to profound visual disability. Notably, the course of the disease varies with genetic differences as well as inheritance modes, with some patients exhibiting a slower course of progression than others.

The Current State of Treatment Options

“While in the past the diagnosis of RP was purely descriptive with no treatments being available or even on the horizon, recently the field of hereditary retinal dystrophies has truly leaped into a new era,” says Boris Rosin, MD, PhD. “This is due to the retina being surgically accessible and manipulable, largely due to the amazing advancements in the field of vitreoretinal surgery, thus allowing the introduction of exciting new treatments for hereditary retinal dystrophies.”

Dr. Rosin, the Martin McGuinn Retina Research Fellow and a clinical instructor in the Department of Ophthalmology explains that this new era in retinal research includes a variety of novel treatment options currently in different stages of research and development, such as gene therapy, cell therapy, retinal prostheses, retinal bypass, and others.

Gene therapy employs viral vectors, which are emptied of their infected component and loaded with a correct copy of a gene. The vectors are then delivered to the retina, either by injection into the eye or specifically under the retina, infecting the retinal cells and forcing them to express a correct copy of the malfunctioning gene. “With the FDA’s approval of the first such agent, Luxturna, there is little doubt that this approach will continue to evolve,” advises Dr. Rosin.

Cell therapy is, in essence, a form of replacement therapy, where stem cells are introduced to the retina, replacing damaged photoreceptors. This approach has the advantage of being both non-gene-specific and can thus be potentially used for any hereditary dystrophy. However, Dr. Rosin points out that the research in this field is not as advanced as in the other approaches presented here.

Retinal prosthesis, or artificial retina, is an approach that can be attempted in patients with poor residual visual capacity. One such device, the PRIMA implant, is an array of photovoltaic cells implanted under the retina and conveying the visual information directly to the ganglion cells comprising the optic nerve. UPMC is currently participating in a trial of employing the PRIMA device in patients with advanced Age-Related Macular Degeneration and is, in fact, the first center in the US to have performed two such procedures. Boris Rosin is working with Dr Martel and Sahel on this cutting edge study.

Visual restoration can also be attempted at the level of the central nervous system. Here, the visual information would be reintroduced directly to the brain, in essence, bypassing the retina altogether in patients with impaired optic nerve. Dr. Rosin adds that “Visual and other sensory substitution is an active field of research in Neuroscience and the topic of research of several groups at Pitt and CMU, providing for exciting inter-institution collaboration in the City of Pittsburgh.”

A Bright Future Ahead

Just in recent years alone, the field of ophthalmology has witnessed a therapeutic revolution in our way of dealing with hereditary retinal dystrophies in general and RP in particular. What previously was considered to be a purely observational discipline, can now offer a concrete treatment for at least one disorder and many exciting new possibilities in the near future for the others.

“Undoubtedly, the next few years will see the expansion of our therapeutic repertoire, providing significant relief to what not so long ago were considered intractable disorders,” states Dr. Rosin. “At UPMC and the University of Pittsburgh, along with the generous support of the Eye & Ear Foundation donors, we will continue to strive to develop new treatments and methods for dealing with these highly debilitating diseases.”

This type of innovative research is only made possible with support from generous donors to the Eye & Ear Foundation. If you would like to be a part of this groundbreaking work being done, please consider making a gift to help support our research.

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