The eyes are unwell. Their childhood suppleness is lost. The lenses, as we log hours on this earth, thicken, stiffen, even calcify. The eyes are no longer windows on souls. They’re closer to teeth.

To see if your own eyes are hardening, look no further than your phone, which should require no exertion; you’re probably already there. Keep peering at your screen, reading and staring, snubbing life’s third dimension and natural hues. The first sign of the eyes’ becoming teeth is the squinting at phones. Next comes the reflexive extending of the arm, the impulse to resize letters into the preschool range. And at last the buying of drugstore readers.

Virginia Heffernan (@page88) is an Ideas contributor at WIRED. She is the author of Magic and Loss: The Internet as Art. She is also a cohost of Trumpcast, an op-ed columnist at the Los Angeles Times, and a frequent contributor to Politico. Before coming to WIRED she was a staff writer at the New York Times—first a TV critic, then a magazine columnist, and then an opinion writer. She has a bachelor’s degree from the University of Virginia and a master’s degree and PhD in English from Harvard. In 1979 she stumbled onto the internet, when it was the back office of weird clerics, and she’s been in the thunderdome ever since.

Modern medicine offers little apart from magnifying glasses to treat presbyopia (from the Greek presbus, meaning “old man”). But those $3.99 specs will get you on your feet just fine, which is to say, you can once again relish your phone without squinting or arm-stretching. A remedy for farsightedness evidently succeeds to the degree that it restores a woman or man to the comfortable consumption of texts, email, ecommerce, and social media on a glazed rectangle of aluminum alloys held at a standard reading distance of 16 inches. With reading glasses we live again.

Doesn’t this seem like an unwholesome loop? The eyes may be unwell, but the primary object of our eyesight seems corrosive. We measure our vision against the phone, all the while suspecting the phone itself is compromising our ability to see it.

Even if we don’t say out loud that failing vision has something to do with our vastly narrowed visual field, our bodies seem to know what’s up. How convenient, for example, that you can turn up a phone’s contrast and brightness with a few taps. If perception can’t be improved, objects can be made more perceivable, right? But then the brightness seems, like morphine, to produce a need for more brightness, and you find yourself topping out, hitting the button in vain for more light only to realize that’s it. You’ve blinded yourself to the light that was already there.

Having recently, in my forties, gotten reading glasses, I now find myself having to choose between reading and being, since I can’t read without them and I can’t see the world with them. The glasses date from a time when reading was much rarer a pastime than being; you’d grope for them to see a book, while relying on your naked eyes for driving, talking, walking.

But of course now so many of us read all day long. And I opt to flood my field of vision with the merry play of pixels and emoji rather than the less scintillating, brown-gray “real world.” This means wearing the reading glasses, even on the street, and affecting blindness to everything but my phone.

What might modern vision be today without the phone as its reason for being? If you were a nomadic goatherd in the Mongolian grasslands, you might not even consider presbyopia a pathology. Many nomads carry cell phones for calls and music, but, except to play games, they rarely gaze at them. Instead, they rest their eyes on the ever-moving flock, alert to vagaries in the animals’ collective configuration and inclinations; but simultaneously they soften the vision to wide angle, so as to detect peripheral anomalies and threats. On camelback in the wide-open grasslands, the eyes line easily with the horizon, which means their eyes take in distance, proximity, an unpixelated spectrum, and unsimulated movement. A panoramic view of the horizon line roots the beholder in the geometer’s simplest concepts of perspective: foreshortening, a vanishing point, linearity, and the changeable shadows cast by the movement of the sun over and under the horizon line. That third dimension—depth—is never, ever forgotten by the nomads. The sun rises and sets on depth.

See more from the Life Issue.

April 2018. Subscribe to WIRED. Nik Mirus

Depending on your after-hours curriculum in Mongolia (cooking, talking, playing the fiddle), you might rarely even need to do what digital moderns never stop doing: recruit the eye’s ciliary muscle and contract it, releasing tension in the ligaments that suspend the eye to acutely curve the lens and train it to a pixelated 1.4-milimeter letter x on, for instance, a mobile news app. If you explained to a nomad the failures of her aging eyes, she might shrug: Who needs anxious ciliary muscles?

Indeed. And the use of those muscles by digital moderns gets even more complicated when we encounter our x’s not on paper—carbon-­black ink, like liquid soot, inscribed on bleached pulpwood—but on screens. That’s where we come across the quivering and uncertain symbols that play across the—surface, is it? Where are they exactly? Somewhere on or in our devices. No wonder the eyes are unwell.

Every vocation has consequences for eyesight. Ice fishermen can go snowblind. Welders suffer arc eye. Ships’ lookouts hallucinate. Academics develop myopia. And texters—call it an avocation—have blurred vision.

There are at least two recorded cases of something called smartphone blindness. The New England Journal of Medicine notes that both patients had been reading their phones in bed, on their sides, faces half-hidden, in the dark. “We hypothesized that the symptoms were due to differential bleaching of photo-­pigment, with the viewing eye becoming light-adapted.” Differential bleaching of the eyes! Fortunately, smartphone blindness of this kind is transient.

The blanket term for screen-borne eyesight problems is computer vision syndrome, an unsatisfactory name given to the blurring, dry eyes, and headaches suffered by the people of the screen. The name is unsatisfactory because, like many syndromes, it describes a set of phenomena without situating them in a coherent narrative—medical or otherwise. For contrast, arc eye is a burn: Welders get it from their exposure to bright ultraviolet light. Snowblindness is caused when corneas are sunburned by light reflecting off snow. Hallucinations afflict lookouts because, as Ishmael explains in Moby-Dick, they’re up at odd hours and alone, parsing the “blending cadence of waves with thoughts” for danger, whales, or other vessels; the brain and eyes are inclined to make meaning and mirages of undifferentiated land- and seascapes where none exist.