How Tooth-in-eye Surgery Works

These days, across the Earth, there are perhaps 45 million blind people. Of those, around 9 million may be blind because of corneal problems.

The numbers were different back in the 1960s, but the problem was not — people were suffering from acute cornea damage, and there was no contemporary way to restore their sight. It was then that an Italian eye surgeon named Benedetto Strampelli decided to try new techniques to help people who had no other surgical options.

He knew that damaged eyes don't produce enough tears to support a new cornea, leaving the tissue rough, dry and with an almost skinlike texture. He also knew that a simple plastic lens typically wouldn't do the trick because the body often rejects foreign objects, making synthetic replacements difficult or impossible.

The solution, he thought, was to embed a see-through, plastic cylinder into the body's own tissues. The resulting structure would be strong, scratch-resistant and made up of your own DNA, lowering the possibility of rejection.

One of the biggest challenges was finding a way to create a long-term bond between living tissue and the plastic lens. That meant first locating an appropriate foundation for a lens. Strampelli thought that perhaps most suitable building block would be a hard substance made to last in a warm, mucous-filled environment like the eye.

A tooth, he thought, might be the perfect candidate. So he began exploring the idea of extracting a tooth and integrating it with a lens, and then implanting the entire contraption into a blind eye, essentially creating an artificial window.

His plans worked well enough to inspire other doctors to try the technique. One of his protégés was Giancarlo Falcinelli, who refined and simplified the concept over the course of hundreds of repetitions to make it easier to perform, with better and longer-lasting results.

Falcinelli's procedure is currently regarded as the most effective way to rebuild otherwise unsalvageable corneas (called end-stagecorneal blindness) and is called modified osteo-odonto-keratoprothesis (MOOKP).

The MOOKP procedure is an elaborate medical dance, one that requires the cooperation of not one but two corneal surgeons, an oculoplastic surgeon (a specialist in plastic surgery of the eye), a dentist and anesthetist. The operation actually occurs over two stages that take place months apart.

The first stage requires the extraction of a tooth. Surgeons typically choose one of the canine teeth because they have the longest roots. If you're one of many people terrified of dentistry and you're familiar with the literary concept of foreshadowing, take the phrase "because they have the longest roots" as your cue to begin shuddering in horror.

The surgeon knows she needs to take a good amount of the root tissue, as well as the periosteum, a fibrous layer made up of collagen and nerve fibers that covers all of your body's bones. So she cuts deep using a motorized saw to take out the tooth, leaving behind a rather gory gaping hole. This process is considered one of the most difficult aspects of the procedure because if the tooth fractures or too little tissue is taken, the whole operation will fail.

During the same operation, doctors also prepare the damaged eye, scraping away old scar tissue.

Once the surgeons have harvested the canine, the dentist carves the tooth into a smaller shape and drills a hole into the center. Then a plastic lens is inserted into the hole and dabbed with a bit of dental cement, creating what some specialists call a bio-integrated prosthetic unit.

The unit is implanted into the patient's cheek and left there, so the tooth periosteum and blood vessels grow around the tooth-lens combo, securing the lens to the tooth and providing the contraption with the circulation it will need to survive in the eye.

Two to four months later, surgeons retrieve the tooth from its cheek incubator. They then make a hole in the center of the cornea and insert the tooth and lens, grafting tissues around it to keep it in place. Each incision is sutured and the eye is re-inflated with filtered air. When successful, the operation means patients can immediately see the world around them.

In spite of improvements in medical technologies, tooth-in-eye surgery is still relatively complex and costly. Although it's been around for decades, it wasn't performed in the U.S. until 2009.

The doctor-patient interaction is extensive and occurs over the course of several months. This includes pre-operation evaluation, two surgeries and follow-up visits. The surgeries themselves are complex. Each of the operations may last between four and six hours.

Because of the complexity and potential for side effects, doctors will perform the procedure on only one eye, even if the other eye is blinded as well. That leaves a "spare" just in case the MOOKP fails and the doctors need to try again. Happily, when it works, the results tend to last. After nine years, more than 70 percent of patients retain their best possible visual sharpness [source: Falcinelli et al.].

Few doctors have the training necessary for MOOKP. It takes years to master the procedure. And not many hospitals specialize in providing this service. Those two factors are the reason that the total number of procedures is still in the hundreds and not the thousands.

There's also the fact that some people are put off by the final appearance of MOOKP patients. The eye loses much of its natural look, replaced by a skinlike eye punctuated in the middle by a black hole. The overall effect has been compared to a sci-fi cyborg eye, which for some people may be a selling point but for others feels disfiguring.

The reality is that MOOKP is reserved for worst-case scenarios in which no other surgical techniques will work. If you're in a condition where tooth-in-eye surgery is your only option, you've likely already explored every other possibility.

When it's necessary, though, MOOKP offers hope to people who otherwise may otherwise never see again. With just a bit of material from their own teeth, they may have the joy of experiencing blue skies and fluffy clouds, the sight of their families and take in the joy of simply being able to walk city streets, soaking up the colors and textures all around them.