Photo via Flickr user Ben Churchill

"Once, I compared my feelings to a computer," said Bobby, a 56-year-old man who lives in Central Europe. "The system—my mind—contains a piece of software, but the hardware—my body—does not have the appropriate equipment. And the system keeps asking: 'Attach the device, please, and press any key.'"

Bobby is talking about glasses. Specifically, glasses strong enough to blur his vision; glasses that signal to the world that his eyes are imperfect. Bobby's eyesight is fine. He wishes it wasn't. Since childhood, Bobby has wanted to become visually impaired. This desire is so visceral that it's led him to adopt a lifestyle of blindsimming, or simulating blindness by obstructing his own vision.

"It is difficult to explain," he said of the urge. "I have always wanted to be visually impaired. Always." He says that his preferred method of blindsimming—wearing glasses over contacts to make his vision blur—makes him feel "cool, complete, and satisfied."

It wasn't until Bobby reached his 20s that he began experimenting with bindsimming. At first, he wore strong glasses that distorted his vision so much that he couldn't cross a street without watching the back of the person in front of him. Then, he started wearing an occluder—an eyepatch made of plastic, often used to fix children's lazy eyes—or wore glasses over contacts to simulate myopia. (Bobby is a partial blindsimmer: He wants to be extremely nearsighted, not fully blind.) At one point, he wore glasses over contacts every day for six years, but the blindsimming stopped when he moved in with his current partner, who he says doesn't understand his "strange desires."

Bobby's desire to be visually impaired, as a seeing person, is a manifestation of body integrity identity disorder (BIID), a condition so rare and controversial that it has yet to make it into the DSM. The most common cases of BIID are people who want to have a healthy limb amputated or paralyzed; while rarer, there are also cases of people who want to be blind, deaf, or castrated.

The earliest recorded instance is from the 18th century, when a man held up a surgeon at gunpoint and demanded the amputation of his perfectly healthy leg, but the term wasn't invented until 2004, when by Dr. Michael First, a Professor of Clinical Psychiatry at Columbia University, wrote the seminal paper exploring the subject in the journal Psychological Medicine.

According to Dr. First's research, the "strange desires" of BIID usually start in childhood, and can be triggered or crystallized by the sight of someone who has that condition. Those who suffer from BIID report "a chronic, nagging sense that their body simply isn't right," as Dr. First explains it. One of the men he studied described feeling "over-complete" with his two healthy legs. He only wanted one.

"My sight was a prison. When I pretended to be blind, I felt free." — Jewel Shuping

Recently, neurologists have joined in the research. They call the disorder "xenomelia," from the Greek "xeno" (foreign) and "melos" (limb). A research team in Zurich performed brain scans on a handful of men who wanted to be amputated, and found reduced cortical thickness in the subjects' superior parietal lobes, which is the part of the brain responsible for spatial awareness and "body ownership."

Still, this doesn't prove that the disorder is purely neurological. As the neurologists in question write, "It remains unclear whether the structural alterations are the cause or rather the consequence of the long-standing and pervasive mismatch between body and self." In other words, if someone constantly favors their right leg because they don't want their left one, it's possible that their brain would change to reflect that preference.

While the desire for paralysis or healthy limb amputation has been part of the collective consciousness for some time now (there are even several movies about it), the desire to be blind hasn't been as visible. Recently, though, a practicing blindsimmer named Jewel Shuping captured the public's attention when she claimed to have blinded herself with drain cleaner, eventually causing enough damage to one eye that it had to be removed. (Shuping claimed a "sympathetic psychologist" helped her with the procedure, though both Dr. First and Snopes find this hard to believe.)

"My sight was a prison," she told me. "When I pretended to be blind, I felt free." Like Bobby, she can hardly remember a time when she didn't feel like this. "My mother said she found me walking the halls in the dark when I was three. When I was six, I started staring at the sun." Today, Shuping seems happy with her new condition. Her Twitter bio reads, "Just your everyday blind woman, trying to deal with everyday life."

Most blindsimmers aren't so open about their lifestyle. While Dr. First has spoken to 150 people with BIID and estimates there may be "thousands" throughout the world, the disorder is shrouded in secrecy and shame. For years, Bobby kept his urges an "absolute secret," and even today, only a few people know about his desire to be partially blind. The fact that his partner does not accept his condition is devastating for him. "She will never ever understand," he said. "I do not speak about it with her."

"Nobody goes blindsimming because he or she thinks it is funny to pretend to be blind. They do it because they have to." — Bobby

For a long time, he grappled with his desires in secret, and describes that period of his life as "lonely, fucking lonely, and strange." But then Bobby stumbled across a variety of online communities—first a group of glasses fetishists, then a blind fetish community, and then finally a group of blindsimmers themselves—and he experienced an overwhelming sense of relief.

"Imagine yourself having blue hair or six fingers," he told me. "You believe you are the only person in the whole world who is like that. And then you find the same people: 'Wow! I am not alone! I am not a freak! There are more people like me!'"

The online blindsimming communities became a space to swap tips, write fan fiction, and share Photoshopped photos of celebrities wearing thick glasses. The conversations can be amazingly technical: They help each other calculate "vertex distance" and "effective power on the cornea." They brainstorm ways to induce myopia. They perform complicated equations concerning prescription strengths. They talk, cautiously, about hospitals in Jalisco and Tijuana that are willing to remove their eyes' crystalline lenses—the transparent bit behind your iris that helps you focus on objects at different distances. They discuss the many tools of faux-blindness: walking canes, dark glasses, and the opaque contact lenses used by stage actors who play blind characters.

The blindsimmers also help each other invent excuses for the inevitable questioning, when a friend notices that your glasses are thicker than they used to be or that you're suddenly using a cane. In a discussion on Eyescene.net, an eyewear-interest site with a subsection of blindsimmers, one user suggested: "The trick for avoiding much comment is to retain the same frame style. Most people do not notice the lenses nearly as much as the frames... If there is a comment about the prescription, just say that law school is pretty hard on the eyes, without going into much detail."

Unlike other groups for common interests, the online blindsimming groups—some of which have 300 or 400 users—are underscored by a sense of deep pain and desperation. "Nobody goes blindsimming because he or she thinks it is funny to pretend to be blind," says Bobby. "None of them has ever said to themselves, 'Let us start doing this.' None of the real full or partial blindsimmers do it for fun. They do it because they have to."

This urge, this itch, this lack of choice—it all begs a very difficult question. If someone has body identity integrity disorder, and if they are miserable because of it, is surgery ever an option? Is it ever OK to knowingly damage a healthy body?

"People say, 'How can you make me suffer with this?'" Dr. First explained. "It's difficult telling someone that surgery shouldn't be available to them, that they'll have to live with this for the rest of their life. There's no good answer; it's a very tough situation."

Dr. First is aware of 20 to 30 instances where people who longed for an amputation actually went through with medically-sanctioned surgeries—and are happier for it. With the limb gone from their body, they feel, ironically, whole. Because of this, Dr. First doesn't explicitly oppose surgery, but he lays down three conditions that must be met for the surgery to be ethical. After all, once someone goes through with the surgery, they have to live in this new-ish body forever. "Everybody's worst nightmare is that someone gets this surgery and then regrets it," he says.

Here are the three conditions: "One, the person has to be competent to make the decision and must understand the risks and the benefits. Two, the surgery has to be framed as a treatment. We have to conceptualize it as doing this to treat a condition. Three, there should be some reason to believe that the treatment will be effective."

This third criterion can complicate the options for blindsimmers who want to be blind for real. Shuping provides some evidence that purposeful blinding was effective treatment, even though Dr. First finds it hard to believe that her "treatment" was sanctioned by a respectable medical professional, and worries that her psychologist's actions were "completely irresponsible and unprofessional." Shuping told me that she knew the psychologist for a year, and that they worked through many different forms of therapy—cognitive behavioral therapy, talk therapy, meditation, hypnosis—before deciding to move ahead with the drain cleaner.

But there are still too many unknowns about her case for Dr. First to declare this an example of an ethical procedure, and so as things stand right now, he believes that any sort of eye surgery for blindsimmers would be "totally speculative." Shuping herself told me that she made her blindsimming friends swear that they wouldn't follow in her footsteps, since blinding by drain cleaning is highly dangerous. "It can be lethal. It can cause severe damage to the face. I told them that they had to promise me they wouldn't do it my way if I told them where I did it."

Without properly sanctioned treatments, those with BIID may go to terrible lengths in an effort to get their bodies aligned with their minds. Those who long for amputation have used dry ice to damage their legs so severely that hospitals are forced to amputate. They've built homemade guillotines and attempted to crush their limbs with cars. In 1998, a man died of gangrene after a black-market amputation in Mexico. Some doctors believe that it's better to offer safe, hygienic surgeries to people who might otherwise take matters into their own hands; others think that doctors should keep trying psychotherapy or medication tailored specifically to BIID.

The day after we first spoke, Bobby sent me a long Facebook message. He wanted to make sure I understand one nuance of his condition—the inescapability of it.

"Something deep in our minds, souls, hearts urges us to pretend blindness," he wrote. "It is not our choice. We cannot just stop. We cannot fight it. If we fight it, after a time it bursts out itching, burning, and chasing us to put the glasses on and spend a day the way we need to. We are who we are, because we cannot help not being like that. Believe me, it is not an easy life."

The disorder he described has come to represent, to me, a more nuanced idea of sorrow. Usually, sorrow is spoken of in terms of absence, and it springs up this way in our idioms: "the missing piece," "a hole in my heart," "conspicuous by its absence," "empty nest," "empty-handed," "empty inside." But that's not the only way that sorrow can manifest itself. It can also be characterized by words we associate with joy: excess, abundance. A person with body identity integrity disorder feels perpetually "over-complete." While the rest of us tremble at the thought of loss, loss is what they crave. They have been given too much. They don't want it. They never asked for it.