Eyes are the window to your soul, and that doesn't stop being true no matter how many illegal substances you consume on a night out. But can your eyes really tell when you're actually on something? From pupils the size of a needlepoint to huge black holes with barely visible irises, we snapped our way through Berlin's nightclubs to see if people's eyeballs could tell us the night's story. How much does the size of your pupils actually have to do with the substances you've taken?
The stuff in drugs that makes you relaxed, happy or just really awake not only manipulates the neurotransmitters in your brain, but can also affect physiological processes in your body. This includes the muscles in your eyes that are responsible for making your pupils bigger (to let in more light, for example), or smaller.
Fun fact: Movie-goers with an affinity for drugs rained criticism down on Darren Aronofsky after seeing Requiem for a Dream, in which he uses stylistic closeups of his heroin-addicted protagonists' pupils growing, instead of realistically having them constrict.
But how concretely related are the consumption of drugs and visible changes in the eyes? After our photographic field study, we wanted to get a better answer, so we talked to a few people who would know more about the myth of drug eyes.
"A change in pupil size can be an indication of drug consumption, though it doesn't have to be," explains Heike Krause from the emergency station for people at risk of addiction in Berlin. "The pupils can also widen for if you're an epileptic who's on medication. So we like to look for other, conclusive signs. For example, if someone is heavily sweating."
However, the eyes still seem to offer clear clues to a person's sobriety or lack thereof. Why else would the Hamburg police be running tests on people's pupils? They use a pupillograph, a device that looks like how people in the 60s would have imagined super-futuristic 3D glasses, and it's supposed to be able to tell if a driver is under the influence of drugs or alcohol. But according to Holger Vehren from the Hamburg police's press office, the measuring device isn't "the wonder weapon of drug detection, it's more of a 'pre-test' before a blood test."
The toxicologist Thorsten Binschenck-Domaß went into more detail about the effectiveness of these kinds of light-driven reaction tests. "Cocaine, amphetamine and THC, as well as a limited number of hallucinogens, lead to the pupils' delayed or lack of reaction to light,' he said. "These symptoms can outlast the subjective effect of the substance for many hours and up to two days. They may also lead to an enhanced sensitivity to glare."
Yet a normal reacting pupil doesn't automatically mean the subsequent blood test will come back negative. Although the pupillograph can measure the pupil size and reaction time, that doesn't mean it can tell without a doubt whether illegal substances have been consumed, let alone which ones.
But what's also interesting here is the medical perspective, which is the reason we called up the Charité hospital in Berlin. After many phone calls with people on the drug ward who also don't think the eyes are a great indicator of addictive behavior, we landed in the eye clinic. Their response was as explicit as it was sobering: It's absolutely not possible to tell what drugs someone has consumed by looking at their pupils.