Law enforcement is currently under massive pressure to tackle the core issue of stoned driving: How does one truly determine if a driver is too stoned to safely operate their vehicle

While police have the breathalyzer test to accurately pinpoint a drunk driver’s level of intoxication at the exact time of the test, no clinically-proven test exists for weed. It can take weeks for the body to rid itself of cannabis metabolites; and current urine and blood tests can’t identify whether a driver was stoned at the time of a traffic stop, or whether they had gotten high a week before the test.

This past July, an optometrist patented a new roadside cannabis intoxication test that involves a virtual reality headset and an eye exam. In 2016, Denise Valenti began designing a device called IMMAD, short for “Impairment Measurement Marijuana and Driving.” This device uses a stock Samsung HMD VR headset to test a driver’s peripheral vision by flashing a series of grayscale stripes around a centered black dot. Drivers are asked to click a Bluetooth button every time they see a stripe.

This test is based upon research suggesting that cannabis can negatively impact peripheral vision and reaction time. Individuals who are under the influence of cannabis are expected to accurately identify fewer stripes than a sober individual. “Marijuana causes temporary paralysis of the cell operating in the retina,” Valenti explained to American Inno. “So when you have certain neurologic deficit in your retina, you just can’t see the stripes. If you can’t see, you can’t drive.” 

“The final version will be a quick, simple, objective, sensitive, specific test of marijuana driving impairment for law enforcement,” said Valenti to TruckingInfo. “This test will be threshold related and have a number value compared to a large normative data base. That test will take two minutes per eye.”

Gallery — Photos of Cops Smoking Weed:

Although she is fighting to crack down on stoned drivers, Valenti is not actually opposed to cannabis reform. Over the past two years, she has researched the therapeutic potential of marijuana to treat Alzheimer’s, Parkinson’s, and other neurodegenerative disorders.

“Now that we have the legalization of cannabis products, here in Massachusetts and in other states, I think it is becoming more important to be able to assess intoxication, especially for driving where it can be about life and death,” said Marc Pomplun, a University of Massachusetts Boston professor who helped Valenti design IMMAD, to American Inno.

Valenti and Pomplun are now working to add eye-tracking technology to the headset. This technology aims to identify both regular cannabis users as well as drivers who dabbed before driving, based on research finding that these specific cannabis users often have more sporadic and unstable eye movements. The design team is also working to improve the tests’ overall accuracy.

“We have to make sure [IMMAD] is actually sensitive to a degree,” Pomplun said. “It has to be specific enough so that it only responds to marijuana and nothing else.” Valenti added that “we know we have a ways to go. But we are slowly moving forward. This is just the first generation of the prototype. Just imagine what this technology can do.” 

Valenti hopes to make the test available to all law enforcement agencies, but the design team has a long road ahead of them before that hope can become a reality. In order to be approved for use, IMMAD must undergo additional testing and research, and then gain approval from the Food and Drug Administration as well as the court system of any state that wishes to implement the test. The testing process is further complicated by the fact that Massachusetts forbids researchers from getting subjects high during clinical research tests.