Denise Valenti, OD, has come up against a Gordian knot of sorts with her IMMAD device to provide police with a roadside, objective measurement for drivers suspected of driving under the influence of marijuana. The company, IMMAD, is in the proof of concept stage, she says, somewhat stymied by the challenges that comes from doing marijuana research. “We have been declared by the regional authorities as a marijuana business, so we don’t qualify for traditional banking or small business loans. And without funding for more research that provides us with more data on people, we can’t get investors,” she says. “I have no shortage of willing volunteers,” she says, laughing. But what Dr. Valenti and her team are seeking is hard science that can help their device reach Daubert or Frye standards—standards that should be upheld in court. What limited, legally dosed participant data there is will be presented at an upcoming research conference.
That hasn’t deterred the team yet. And as more states approve recreational and medical uses of marijuana, the need for such a device is going to become more urgent), she says. Indeed, it’s possible that even public universities might be able to craft research that keeps them within federal guidelines but permits the study of marijuana usage. Already, some European studies about the effects on the visual system from chemicals that are byproducts of marijuana—THC and CBD—as well as any emerging trends that might show that marijuana users are involved in accidents is going to boost more interest on vision and marijuana use. Notably, a December 2016 article in JAMA Ophthalmology by Thomas Schwitzer, MD, et al, titled “Association Between Regular Cannabis Use and Ganglion Cell Dysfunction,” highlights the same ideas used in IMMAD development. The study, which noted it is probably the first to show retinal ganglion cell dysfunction in regular cannabis users, concluded, “Assessments of retinal function could therefore provide valid, reliable and reproducible measurements that could reflect cannabis-associated brain dysfunctions.” There is very little research on marijuana in humans and what exists often does not meet accepted research standards, she says. However, a notable exception is work that had been done on the visual system in the 1970s by Anthony Adams, OD; Brian Brown, PhD; Gunilla Haegerstrom-Portnoy from University of California School of Optometry; the late Merton Flom, OD, PhD; and Reese T. Jones, MD, PhD.
The studies of human function were performed at the University of California Berkeley School of Optometry. This was a placebo-controlled, double blind study that had utilized National Institutes of Health-controlled marijuana. The results indicated dysfunctions in glare recovery and perception of the color blue. This work agrees with another publication of Dr. Schwitzer’s where he reported that, in a single patient who used marijuana acutely, dysfunction was not only in retinal ganglion cells but also in photoreceptors, she says.
Dr. Valenti says that in developing the IMMAD device, the team has been using the Humphries Welch Allyn Frequency Doubling Technology, (FDT) used to show visual system deficits in patients with Alzheimer’s and Parkinson’s diseases. “With younger, healthy, legally dosed volunteers, we have been able to show that marijuana does impact the communication of the ganglion cells. Someone who has smoked marijuana may still have 20/20 vision, but the ganglion cells have to communicate to understand complex systems like motion, depth and contours. Those are all essential to driving,” she says. The FDT can show, objectively, that vision is impaired, and Dr. Valenti says that the commercial test, IMMAD will be refined for measuring marijuana impairment by customizing the targets and the overall strategy to assess the retinal functions. The idea would be to have this test on a tablet that police officers could administer immediately.
There are some tests available to police now, but they’re limited and may not stand up in court by themselves. There is ongoing research to adapt breathalyzer technology. While blood tests can measure THC, they currently are not being evaluated to test for CBD, the cannabinoid that is often considered for medical treatments and is an essential part of medical marijuana but has been largely been bred out of marijuana for recreational use.
There are some new smartphone apps for consumer usage that allow people to test their mental and physical performance. Two of these are My Canary and DRUID. Dr. Valenti says that the upside to having these apps available is that it could spread recognition that marijuana use does actually cause impairment. “Unlike alcohol, where the user has some sense as to whether he or she is impaired, marijuana affects the brain similarly to Alzheimer’s. Marijuana users often don’t recognize at all the extent or length of time that the impairment affects them.” She cites a 1991 study with airline pilots who flew simulated airplanes at several intervals after smoking one marijuana cigarette (or a placebo). The results of the study showed that the pilots had some level of impairment, even 24 hours after smoking marijuana, and their lack of recognition of impairment was considered to be significant.
“Developing a forensic tool is different,” she says. “If it can’t stand up in court, then it’s not as valuable to those in law enforcement who currently struggle to keep roads safe.”
Follow Dr. Valenti’s research and IMMAD developments here:
Click here to read the abstract of the JAMA Ophthalmology story.
And you can read the abstracts of the studies from the 1970s mentioned here and here.