Imagine waking to a bright, sunny day, but not really being able to see. Some people go their whole lives without witnessing that vivid red ball from their youth or the facial features of a loved one. Kristina Narfström, a veterinary ophthalmologist at the University of Missouri, is doing research that promises to provide some light at the end of the tunnel.
Narfström began her veterinary medical career in her native Sweden, where she taught at the veterinary school for more than 20 years. She seeks solutions for retinal diseases in the outer retina, but more specifically in the photoreceptor (visual) cells, the rods and the cones. She is focused on diseases that cause complete blindness. Her subjects involve mainly cats and dogs, which suffer from many of the same ailments in the eye as do humans.
The retina, Narfström says, is extremely interesting and “very complex.” she explains: “It is in the retina where everything important happens in the eye. Light falls onto the retina, causing biochemical and photochemical processes to occur, which result in small currents that then pass to the brain where there is a transformation into images that we can see.”
But here is the problem. When there is no electrical response produced in the retina, currents never make it to the brain. Narfström’s research, therefore, is twofold: 1) to prevent photoreceptors from dying and 2) to replace dead or dying photoreceptors. There are ways to slow down photoreceptor cell death, but replacement therapy still has a long way to go.
One method for substituting for dead photoreceptor cells is by using stem cells, a practice that has been linked to the treatment of a host of medical conditions including Alzheimer’s disease, spinal cord injury, and blindness. The other alternative involves using a tiny microchip to get the electrical juices of the eye flowing. This device, known as an Artificial Silicon Retina (ASR), is conceptually similar to a bionic eye.
The microchip trumps science fiction, however, because it actually works. Optobionics, the company that produced the chip more than 15 years ago, did early test trials on humans. These chip prototypes were promising and offered some visual enhancement. Dr. Narfström became involved with the company to do more basic research, for example treating her cats affected by a blinding photoreceptor disease.
Powered by natural light, the wireless two-millimeter chips contain about five thousand microphotodiodes, which use an electrical impulse to stimulate retinal cells. The electricity produced by the microchip also helps preserve damaged or dying cells in the retina by providing a small current, thereby enhancing the production of some preservative proteins. The treatment seems to work immediately, and it appears to last for years. As such, it can be used to treat an array of blinding conditions including end-stage retinitis pigmentosa (RP) and age-related macular degeneration (AMD). “With further development you should be able to obtain very nice results,” says Narfström humbly.
When it comes to curing blindness, she explains that there are other more invasive treatments, but that she wants to develop cures that are as painless as possible. “I love my animals, and I feel really bad for them when I see them bumping into things,” Narfström says. “I don’t want to hurt them; I want to treat them.”
One less invasive treatment is gene transfer. Narfström uses this method to correct protein defects or specific mutations in the eye. This procedure involves transferring DNA into the nucleus, which then produces the correct protein that is initially abnormal or missing.
Narfström reports that methods for replacing photoreceptor cells (transplantation) still have a long way to go, but the outlook for this research is also promising. She remains hopeful about the prospects of these treatments for visually impaired human beings as well as animals.
While most of her time is dedicated to research, Narfström also takes pride in her teaching. In fact, the veterinary ophthalmologist lectures all over the world in classes and at conferences. She tries to instill a high level of interest in research for her students, with the hope that they will one day pioneer their own innovative studies: “There’s so much to do there, especially when it comes to comparative research, not only in regard to the eye, but also in relation to other diseases.”