Virtual reality on the horizon for treatment of glaucoma

February 9, 2018

One laboratory is at work on new devices that use visual stimuli to prompt retinal ganglion cells to regenerate, while two other researchers describe techniques through which virtual reality might diagnose the disease more accurately than standard automated perimetry.

 

Virtual-reality devices not only may diagnose glaucoma, but also may treat the disease, according to researchers.

"In virtual reality, you can harness a ton of the physiology of the human being," said Andrew D. Huberman, PhD, associate professor of neurobiology and ophthalmology, Stanford University, Stanford, CA.

His lab is working on new devices that use visual stimuli to prompt retinal ganglion cells to regenerate, explained Dr. Huberman at the 7th annual Glaucoma 360 New Horizons Forum, hosted by the Glaucoma Research Foundation.

Two other researchers at the session described techniques through which virtual reality might diagnose the disease more accurately than standard automated perimetry.

In vitro studies have shown that retinal ganglion cells respond to stimulation.

"If you stimulate axons, they grow," Dr. Huberman said.

 

Likewise, reducing activity for these cells reduces axon growth. Experiments in animal models of glaucoma have reinforced that finding, he said.

Virtual reality could provide the needed stimuli by using effects that activate different retinal ganglion cells, Dr. Huberman said.

"We can now know what's going on in the retinal and in what locations the damage is," he said.

For example, simulations of falling trigger physical sensations. He recalled stepping backward after seeing a virtual reality depiction of a snake.

The lab has begun recruiting subjects for a clinical trial in which the researchers will test their baseline vision, provide virtual reality stimulation, then retest the patients' vision to look for improvements.

For the approach to work in humans, they will have to spend a lot of time using virtual reality devices, said Dr. Huberman, perhaps a half hour per day. So designers will have to "make it entertaining or at least not boring."

 

In one scenario, patients enter a simulated museum gallery. Each painting displays a pattern of dots designed to trigger maximum firing of different ganglion cells down to the brain.

Although he is not a clinician, Dr. Huberman said he receives messages every day from patients seeking help.

Virtual reality could also play an important role in diagnosing and monitoring glaucoma, said Felipe A. Medeiros, MD, PhD, a professor of ophthalmology, Duke University, and co-founder of nGoggle virtual reality company.

Standard automated perimetry, the gold standard for glaucoma diagnosis, is cumbersome and subjective.

"We can only test patients a few times a year, and the variability makes it difficult to detect progression overtime," Dr. Medeiros said. "Nowadays we see virtual reality everywhere, and I started to wonder how we could take advantage of it."

 

The nGoggle consists of a head-mounted display for visual stimulus provided by a smartphone, and dry electrodes to provide a wireless electroencephalogram. It can output its results either to a tablet or via a Wifi gateway to the internet.

If a person looks at a stimulus flickering at a given frequency, the brain will emulate that frequency, he explained. By displaying letters flickering at different frequencies, the researchers found they could use electroencephalography to determine which letter a subject was looking at, and in this way they could determine what the subject could see.

Comparing this approach as a method of measuring visual field defects, the nGoggle was more accurate than standard perimetry, he said, citing a 2017 report in JAMA Ophthalmology.

The device could be used to measure visual field loss, contrast sensitivity, spatial acuity and face recognition and the ability to carry out tasks in virtual reality, Dr. Medeiros said.

It is objective, has the potential to be used at home, could be used frequently to detect change, and could screen for functional loss in remote locations, he said.

 

Researchers at Vivid Vision, San Francisco, had a similar notion, said Benjamin Backus, PhD, the company's scientific advisor. But instead of designing new equipment, they have focused on using off-the-shelf virtual reality hardware.

"Our strategy to do frequent reliable tests is to use inexpensive equipment," said Dr. Backus, an associate professor of optometry, State University of New York, New York City.

Patients observe two dots and can align them by turning their heads to move them together. Training is automated, and gives feedback as the patient learns. The technology can also evaluate postural control in patients with glaucoma, said Dr. Backus, citing a 2015 article in Ophthalmology