Multiple studies have shown that different types of electrical stimulation to the optic nerve can induce structural and functional restoration after the nerve has been crushed or transected. The idea of using electrical stimulation to restore vision is not new.
Charles Le Roy used static electricity to induce phosphenes, a perception of light, in 1755. Over 250 years later, EBS Technologies is using electrical stimulation to improve vision and quality of life for patients with optic neuropathies.
The goggle-like device delivers electrostimulation above and within the orbital space for both eyes. The intensity of the stimulus is adjusted to produce phosphenes in the absence of light.
EBS has treated about 160 patients in randomized controlled trials, said Jens Ellrich, MD, PhD, chief medical officer, mostly with glaucoma. The company was granted a CE mark in 2013 and has opened five treatment centers. Follow-up has shown an improvement of vision that persists for at least nine months as well as improvements in quality of life.
“We see a significant decrease in visual defects after about 3 months of treatment,” he said. “Axonal regeneration and improvement in RGCs is not a process that happens in a few days, but takes several weeks.”
It may also be possible to improve vision using drug-based techniques. Neurotech Pharmaceuticals is developing an encapsulated cell therapy device that can produce clinically relevant quantities of therapeutic proteins in the eye.
“The effects of ciliary neutrophilic factor (CNTF) in preserving the viability of at-risk RGCs has been well established in multiple ex vivo and in vivo models,” said Charles Johnson, MD, chief medical officer. “The question is how you use it. CNTF has a half-life of less than three minutes, so using it as an injectable is clearly impractical.”
Neurotech’s solution was a propriety cell line derived from human retinal pigment epithelial cells. Cells are transected with CNTF or some other useful protein and encapsulated in a semipermeable membrane that allows ingress of oxygen and nutrients with egress of therapeutic protein. The capsule is attached to the scleral wall using a titanium suture clip.
Phase I trials in 11 glaucoma patients show statistically and clinically significant improvements in vision in the treated eye versus untreated eyes in the same patients. Implants secrete about 20 ng of CNTF daily. Improvement in visual field and contrast sensitivity can be seen within a month and persist at least 18 months.
More from G360: Glaucoma cure may be found in newly discovered biomarkers
“We have an apparent improvement in visual field and contrast sensitivity,” Dr. Johnson said. “We are moving forward with randomized controlled trials. The neuroenhancement signal, if it is replicable, will be seen within six months. We plan to initiate those trials the first half of this year.”