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How Tooth-in-eye Surgery Works

If the thought of eye surgery in general makes you squeamish, this one may have you tensing up as you read. But it’s a fascinating innovation in sight restoration.
If the thought of eye surgery in general makes you squeamish, this one may have you tensing up as you read. But it’s a fascinating innovation in sight restoration.
© Mark Samala/ZUMA Press/Corbis

Your eyes are one of nature's greatest evolutionary triumphs. With a few quick glances, humans can find food, perceive danger, steer a high-speed vehicle, locate mates, or, you know, sit on a couch and watch Netflix. But when your eyes are damaged by accident or disease, your world becomes infinitely more difficult to manage. It's a good thing, then, that you can also see with your teeth.

Using a procedure called osteo-odonto-keratoprothesis (OOKP), or tooth-in-eye surgery, a doctor can implant part of your tooth into a blinded eye and restore sight. It sounds like something from a sketchy B-grade science fiction movie, but this operation has actually been around for decades. In more recent years, researchers have tweaked and improved upon the execution, but the concept is still this same — using part of a patient's mouth material to help reconstruct a damaged cornea.

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The cornea of the eye is the topmost layer that protects your eyeball from the outside world. It's a transparent coating that remains pliable and durable thanks to the tears that keep it moist and crystal clear, providing roughly three-quarters of your eye's focusing power.

The cornea is vital to your vision. If it becomes cloudy or scarred, your eyesight may deteriorate or you many go completely blind. In that kind of unfortunate situation, ideally your doctor would perform a corneal transplant operation, replacing your non-working cornea with a better one from an organ donor. This is a common procedure, with more than 40,000 completed every year in the U.S. alone. Unfortunately, not every person is a candidate for a transplant.

Sometimes, damage to the eye is too severe, perhaps because of a chemical or thermal burn. Or you may have a disorder such as Stevens-Johnson syndrome, which can occur due to an infection or reaction to medication that causes a painful and debilitating rash. These kinds of events may permanently damage the eye's ability to heal itself or to produce the tears that are necessary for supporting a corneal transplant.

In those cases, both patients and doctors may become desperate for a way to fix the eye. That's when a surgeon may chop a tooth from your mouth, suture it into your cheek, and then dig it back out a few months later so she can subsequently zip it into your eyeball.

We are so not kidding. Keep reading and you'll see (perhaps using a tooth-laced eye) how doctors perform this miraculous mix of dentistry and ophthalmology.

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Sharron Kay Thornton underwent the MOOKP procedure in 2009, the first time it was performed in the U.S. She had been blind for nine years prior to the surgery.
Sharron Kay Thornton underwent the MOOKP procedure in 2009, the first time it was performed in the U.S. She had been blind for nine years prior to the surgery.
© Joe Raedle/Getty Images

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.

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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).

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You can see in this illustration that the canine teeth (shown in orange) have longer roots than other human teeth.
You can see in this illustration that the canine teeth (shown in orange) have longer roots than other human teeth.
© BSIP/UIG via Getty Images

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.

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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.

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Cosmetically, tooth-in-eye surgery results don’t mimic the look of the natural eye, but the procedure can successfully restore sight to people who are out of other options.
Cosmetically, tooth-in-eye surgery results don’t mimic the look of the natural eye, but the procedure can successfully restore sight to people who are out of other options.
©Joe Raedle/Getty Images

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.

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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.

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Author's Note: How Tooth-in-eye Surgery Works

Without my glasses, I'm legally blind. I can't read a book or drive a car. To make a sandwich I'd have to hunch over a kitchen countertop to make sure I wasn't squirting mustard all over the floor. Still, I consider myself very fortunate to have the gift of vision, no matter how imperfect. For people who have lost all of their sight, I can only imagine how happy they are to have the option of tooth-in-eye surgery. It's a weird operation, but if it's your only option it would still be preferable to being blind for the rest of your life.

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Sources

  • Cohen, Elizabeth et al. "Tooth Helps Restore Desperate Woman's Sight." CNN. Sept. 16, 2009. (July 17, 2015) http://www.cnn.com/2009/HEALTH/09/16/tooth.eye.vision/index.html
  • Cox, Lauren. "Blind Woman Sees with 'Tooth-in-Eye' Surgery." ABC News. Sept. 17, 2009. (July 17, 2015) http://abcnews.go.com/Health/Technology/woman-regains-vision-tooth-implanted-eye/story?id=8595589
  • Falcinelli, Giancarlo et al. "Modified Osteo-odonto-keratoprothesis for Treatment of Corneal Blindness: Long-term Anatomical and Functional Outcomes in 181 Cases." JAMA Ophthalmology. Vol. 123, No. 10. Oct. 1, 2005. (July 17, 2015) http://archopht.jamanetwork.com/article.aspx?articleid=417283
  • Kaur, N. and A. Nagpal. "Tooth in Eye Surgery." British Dental Journal. Vol. 214, No. 373. April 26, 2013. (July 17, 2015) http://www.nature.com/bdj/journal/v214/n8/full/sj.bdj.2013.383.html
  • Mayo Clinic. "Stevens-Johnson Syndrome." April 22, 2014. (July 17, 2015) http://www.mayoclinic.org/diseases-conditions/stevens-johnson-syndrome/basics/definition/con-20029623
  • Rao, Srinivas K. and Sujatha Mohan. "Modified Osteo-odonto-keratoprothesis." E-journal of Ophthalmology (July 17, 2015) http://www.ejournalofophthalmology.com/ejo/ejo14.html
  • Royal College of Ophthalmologists Guidelines. "Modern Osteo-odonto-keratoprosthesis (OOKP) surgery." Moorsfields Eye Hospital Ophthalmic Research Network. (July 17, 2015) http://www.moorfieldsresearch.org.uk/orntemp/Quality/RGov/Guidelines/ookp.htm
  • Shetty, Lakhsmi et al. "A New Vision Through Combined Osteo-odonto-keratoplasty: A Review." Medical Journal of Dr. D.Y. Patil University. Vol. 7, Issue 3. Pages 272-277. 2014. (July 17, 2015) http://www.mjdrdypu.org/article.asp?issn=0975-2870;year=2014;volume=7;issue=3;spage=272;epage=277;aulast=Shetty
  • The Telegraph. "Blind Father's Joy of Seeing Twin Boys After Tooth Implanted in Eye." Oct. 3, 2013. (July 17, 2015) http://www.telegraph.co.uk/news/health/10352560/Blind-fathers-joy-of-seeing-twin-boys-after-tooth-implanted-in-eye.html

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