Early reports are encouraging from a small study of patients with dry macular degeneration or retinitis pigmentosa. Seven of the 10 people in the study showed improved visual acuity.
The doctors implanted sheets of cells that included the retinal pigment epithelium (RPE) attached to neural (nerve) cells. The RPE is an essential layer of the retina, providing support to the photoreceptor cells. Photoreceptor cells gather in the light and transmit it to the brain. In patients with AMD and RP the photoreceptors die, but the rest of the vision pathway to the brain remains.
The intent of the surgery was to see if the new implanted cells would grow and reconnect to the patient’s remaining retina.
Because this was a Phase I clinical trial, they were also tracking the safety of the procedure, which was excellent, with no tissue rejection.
Four people with dry AMD were part of the trial, along with six people with RP. All four AMD patients showed improved visual acuity and three of the RP patients improved. Remember that the patients entered the trial with vision in the “legally blind” range and even after these improvements, their vision could still be categorized as legally blind. One RP patient maintained the improved vision for six years following the surgery.
This is the kind of study that provides “proof of concept” or “proof of principle”. It gives everyone critical data and experience that lays the groundwork for continued work in this area. Along with others working in the field, they proved that the sheets of cells could be transplanted, could survive, would not be rejected; that the surgery was safe; that the new cells could grow and attach to existing retina. All this shows that more research could potentially provide greater improvements in vision.
For more information on this research and future clinical trials, visit the Retina Vitreous Research Center.