Your eyes are tiny spheres of wonder. They are home to your body’s busiest muscles, its most active neurons and the most transparent cell tissue of any you possess. These intricacies generally go unnoticed when you’re healthy and everything’s running smoothly. But behind the scenes, your brain can spend more than a third of its power parsing what your peepers send along.
I didn’t know any of this when I went in for a recent eye exam, my first in years. I had been coming home from work with itchy, bloodshot eyes. The blurriness of small type on screens suggested that I’d need glasses soon. As expected, I walked away from the exam with a new set of frames.
But the doctor also had some good news I didn’t see coming. After taking an image of my retinas—pumpkin-orange from the camera flash, and snaked darkly with blood vessels—she said I didn’t show signs of high blood pressure, diabetes, or heart disease.
How could she tell? It turns out that your eyes offer a bounty of information about the health of other parts of your body, even the ones that might seem unrelated. An eye doctor might read telltale signs of maladies like stress or inflammation in the condition of your retina or the spidery sweep of your blood vessels.
I walked out of the doctor’s office thinking, “We need to make a video about this.”
The true feat was finding a way to showcase all of this science in a visually interesting way. Senior video producer Hans Weise and I wanted to get a close-up look at this amazing phenomenon. We knew the tiny, fleeting details we wanted to capture, from the incredible textures of the iris to our pupils’ shutter-like twitches, would come to life only with carefully calibrated lighting. But getting the shot wound up being more an act of invention than technology.
From a shadowy corner of National Geographic’s parking garage—a known graveyard for discarded office furniture—we scrounged up a cardboard box and an old bookcase which Hans then assembled into a makeshift lightbox. Subjects could sit with their chins resting just inside, flanked by two small lights, and gaze into the long cylinder of Hans’s macro camera lens. To further control the light, Hans attached a black fabric hood to his side of the booth. Sometimes he’d throw it over himself like an old-time camera operator during filming.
If our approach seems home-brewed, the results were anything but. The beautiful eyes in much of the video are those of more than fifty National Geographic staff members who kindly took a break from photo edits and pitch meetings to visit our booth. A view of their eyes at this scale, the irises in particular, is startling in its diversity and surprising in its intimacy.
We also consulted Dr. Neal Adams, an ophthalmologist and retina specialist whose voice you hear in the video. Adams spent weeks scouring local camera stores for components to connect our camera to his high-powered microscope in hopes of unlocking a deeper look into the human eye.
If a macro lens helps one appreciate the beauty of eyes, a microscope reveals their intricacy and functionality. Blood vessels at this scale are highways teeming with tiny surges of cellular traffic. We were able to catch a glimpse of individual red blood cells hurtling through the tiny channels of capillaries. Seeing that for the first time gave me goosebumps. It’s a reminder of just how much is going on inside us at any moment, in places and at scales we can’t perceive.
This is the crux of why your eyes make such good barometers for your body’s health. Not only do brain tissue, muscles, and blood vessels all meet in your eyes, but it all occurs in a place where, unlike your liver or heart, scientists can actually see without the help of advanced imaging. It makes your eyes ideal for spotting evidence of what Adams calls systemic disorders, which run through your entire body, like diabetes and high blood pressure.
“You may have heard that the eye is a window to the soul,” Adams says in the video. “As ophthalmologists, we believe that the eye is a window to the body.”
Note: The photographs in this post are screen grabs taken from video clips. They are all included in the original video.