Smoking a joint and then driving could land you in jail with this startup's device.

IMMAD, which stands for "Impairment Measurement Marijuana and Driving," is the first of its kind to determine if a driver is intoxicated with marijuana by testing for impaired vision.

The device that uses a Samsung HMD VR headset specifically tests the driver's peripheral vision as this gets loss after consuming marijuana, according to President and CEO Dr. Denise Valenti.

The driver would be asked to look into the headset and click a Bluetooth button every time they see a grayscale stripe flashing around a small black dot. Due to their diminished side vision, the driver may fail to see the flashing stripes.

"Marijuana causes temporary paralysis of the cell operating in the retina. So when you have certain neurologic deficit in your retina, you just can't see the stripes," Valenti told American Inno.

"If you can't see, you can't drive."

Valenti, an optometrist, developed IMMAD's software together with the University of Massachusetts Boston computer science professor Marc Pomplun and some computer science students. They also plan on increasing the device's capabilities by adding eye-tracking to determine regular marijuana users from those who are not.

Consuming marijuana may weaken peripheral vision and slow ­reaction time, which is why the possibility of increased accidental deaths can't be neglected. A study conducted by the Insurance Institute for Highway Safety found a correlation between marijuana legalization and the increased number of motor vehicle crashes.

However, some are doubtful about the study's findings, including Paul Armentano, deputy director of the National Organization for the Reform of Marijuana Laws (NORML), who told Consumer Reports he doubts the investigators found only marijuana as the variable.

However, to David Harkey, president of IIHS-HLDI, "Impairment is impairment, whether it's alcohol or marijuana or prescription drugs."

"Any of those can affect your ability to drive a motor vehicle. You shouldn't be behind the wheel if you're impaired by any substance."

What Valenti wants is to make IMMAD available to law enforcement, and she wants the findings to hold up in court.

"The final version will be a quick, simple, objective, sensitive, specific test of marijuana driving impairment for law enforcement. 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," Valenti said.

Marijuana buds are weighed at a dispensary in Los Angeles
Marijuana buds are weighed at a dispensary in Los Angeles AFP / Frederic J. BROWN