RETITRACK technology could help ophthalmologists with the assessment of neurological disorders.

Although it might not always be apparent, ophthalmologists are regularly in the presence of patients who live with brain disorders and neurological disease. Particularly, conditions such as concussion and traumatic brain injury, multiple sclerosis (MS), Alzheimer’s, Parkinson’s, amyotrophic lateral sclerosis and Huntington’s all produce symptoms in the eye. These symptoms can range from poor depth perception and strabismus to ocular motility issues and retinal thinning. Many times, in fact, the eye is the gateway for diagnosing neurological problems.

Whereas eye-care providers would traditionally have to refer patients based on any suspicions they have, a newly developed technology is poised to offer the opportunity to more deeply investigate neurological concerns present in their patients.

RETITRACK, a novel device by C. Light Technologies, utilizes retinal motion scanning to track eye motion at the cellular level. Future iterations will combine artificial intelligence and machine learning to assess neurological changes visible within the eye.

EYE-BRAIN RELATIONSHIP

Clinically speaking, the eyes are not among the components of the nervous system. But there is a natural relationship between brain function and eye health that has been widely untapped, according to Ari Green, MD, chief of the Division of Neuroimmunology and Glial Biology at the University of California, San Francisco.

“The eye is an outcropping from the brain,” says Dr. Green. “It has a highly evolved sensitive system for interpreting photons of light, and it’s a way of our interacting with our environment through a highly developed sensory system that’s then processed by the brain.” Examination of the eye and eye movement yields information about overall nervous system health.

At the same time, however, patients can’t differentiate between a problem with one or both of their eyes and a problem with their brain, which can lead them to their eye-care provider. “Many times, the only thing that patients know is that something is wrong with their vision,” Dr. Green says. “Patients have reported having vision problems that have ultimately been due to the eye moving more than it should because of a neurological condition, not because of issues with the retina or optic nerve.”

Individuals who are recommended to undergo scanning include those experiencing symptoms related to potential eye motion abnormalities, such as oscillopsia or more general symptoms including headache, fatigue, vertigo, and difficulty concentrating.

Through RETITRACK’s algorithms and instrumentation that examine the retina, eye motion is extracted at the cellular level to depict micromovements of the eye to the slightest degree. And the capacity to study those movements is the capacity to study muscle control, a lack of which can also signal certain neurological conditions. For instance, Dr. Green says RETITRACK can observe ocular motility deficits among the approximately 2.3 million patients in the United States who have been diagnosed with MS per the National Multiple Sclerosis Society. “It’s very common for MS patients to have visual symptoms,” explains Dr. Green.

MEASURABLE MATTERS

The primary clinical intention of the technology is to study fixational eye movement, an overlooked need throughout the industry, says Christy K. Sheehy, PhD, CEO, at C. Light Technologies.

“The eye-care space lacks an objective way to assess eye motion,” she says. “And there are no FDA-approved drugs that allow us to remyelinate or regrow anything back that we lose in the brain. Once a neuron is lost, it is lost. In order for patients to have better quality of life and improved longevity, physicians need to be able to see the small changes that occur in the eye and to treat these small changes as they occur.”

To perform a 10-second scan, the patient leans into a hands-free chin and stabilizing forehead rest to help limit head motion. Tracking scanning laser ophthalmoscopy (TSLO) technology is utilized to record a high-resolution image of the retina at an approximately 5-degree field of view. Eye tracking is based on recorded images — a strip-based tracking pattern where each frame is separated into multiple strips that are cross-correlated or matched with a reference frame.

“The technology can do this because it utilizes raster scanning, meaning pixel by pixel,” Dr. Sheehy explains. “It’s like a camera with a rolling shutter.”

After scanning is complete, the RETITRACK system summarizes captured data within a TSLO report. The output reports quantify both fixation stability and saccade metrics. For fixation, motion changes are plotted in amplitude over time to observe overall stability, microsaccade amplitude, frequency, speed and drift speed and drift ratio. For saccades, target accuracy, latency, speed and overshoot/undershoot percentage is examined. The user can also track metric trends over the course of multiple visits.

“It’s a great fit to be able to use the eye as a window into the brain and to provide that extra level of sensitivity when literally every neuron counts,” Dr. Sheehy says.

The benefits also include understanding how well the eye maintains micro-muscle control and how deficits in that control might be a measurable assessment of decline in baseline neurological function, adds Dr. Green. “The central nervous system is a highly integrated system, but its weakness as a consequence is that when you’re measuring deficit the compensatory capacity can get in the way.”

SUPPORT FOR THERAPIES

Dr. Green theorizes that one of the reasons for the lack of effective therapeutics in degenerative diseases, including the eye, is there are no measurements that show an intervention’s results.

“These very sensitive metrics that this technology can track can show that interventions end the arch on disease progression,” he says. “We don’t want to wait for people to become disabled from their diseases.” OM

RETITRACK has not yet been evaluated by the FDA and is not available for sale in the United States (unless limited to investigational use only).