Sunday, March 2, 2008

7.26 Eye-tooth, tooth-eye

News headline: "Blind Man Regains Sight After Doctors Implant Son's Tooth in His Eye" (Foxnews.com, 28 Feb, 2008)

So what is this all about? Well, there are always surgeries of the last-resort in any field.

As far as the eye, it is always a shame when only the cornea is messed up while the rest of the eye is intact. The logical next step is corneal transplant, typically around 90% success. What about the other 10%, though? They still need to see, don't they? Luckily, there are always surgeons who are willing to tinker, explore, invent, experiment, and cure. We will cite a few examples in this post.

Before we did that, a quick review on what could cause the corneal grafts to fail. Not surprisingly, the major one is allograft rejection, followed by increased intraocular pressure, infection (excluding endophthalmitis), and ocular surface problems. Pre-existing conditions such as diabetes and glaucoma increase the endothelial cell loss hastening the demise of the transplanted cornea. And chemical burn and end-stage dry eye (the latter as part of, e.g., Stevens-Johnson syndrome) both involving ocular surface changes also are major factors in graft failure. Any of the above leads to undesirable outcome, even multiple corneal transplants would not take.

The alternative is then to implant optically active prosthetics directly into the cornea. And if the retina is functioning well, then the patients can regain functional vision often at 20/40 or better.

First example is the Boston Keratoprosthesis developed by Dr Claes Dohlman of Massachusetts Eye and Ear Infirmary in Boston (a schematic is shown below):

The locking ring is titanium, it therefore does not interfere with MRI. This device is first fitted into a donor cornea, then the whole assembly is transplanted as that in normal penetrating keratoplasty. And a therapeutic contact lens is then fitted over the implant, together with life-long use of antibiotic eyedrops. The outcome is quite dramatic, interested readers can look up a news article "No time for tears" in the 5 Nov 2007 issue of Boston Globe.

The post-op appearance (without the contact lens) is shown below:

The second example is OOKP (osteo-odonto keratoprosthesis) developed by the late Dr GianCarlo Falcinelli of San Camillo Hospital in Rome. In patients with severe dry eyes, Boston Keratoprosthesis may not perform well owing to the need for a contact lens - hence the need for adequate tear fluid production. These patients will have to have an eye-tooth implant. Eye-tooth = the upper canine tooth because it situates near the eye. Only a few surgeons in the world are qualified to perform this procedure that include Drs Christopher Liu of Brighton, England, Günther Grabner in Salzburg, Austria, and Konrad Hille of Homburg/Saar, Germany. And a team led by Dr Donald Tan of Singapore National Eye Centre is also active in OOKP implantation. Other eye centers may have also followed suit, check your local listing.

OOKP implant is a two-stage process. The first involves the repair of ocular surfaces using mucosal linings from the patient's cheek, removal of a canine tooth with part of the jaw bone, the tooth is fashioned into a bolt-shaped structure or a flat lamina with a hole drilled in the center, an optical cylinder is then inserted and cemented in the hole. The whole assembly is then implanted in the patient's cheek or under the fellow eye to allow growth of blood vessels. The second stage involves removal of anterior ocular contents and finally replacement with the tooth-bone-cylinder complex, now the tooth-eye.

Not all patients are surgically eligible for the procedures described above. When done, these last-ditch efforts often yield miracle-like results. These surgeons are a special lot, so are the patients who often have already endured multiple surgeries.

8 comments:

Danny Collins said...

If the success rate of corneal transplant is 90%, what's the success rate of OOKP? Although the news of the blind man being able to see again is amazing, the number of qualified surgeons may discourage people from risking the procedure.

EyeDoc said...

Indeed, OOKP should be regarded as the last of the last resorts. With a functional retina ascertained by careful pre-screening, usable vision after surgery is almost guaranteed. All risks will of course be explained to the patient before the procedure.

Thanks for the comment.

We Care India said...

With the eye surgery India the latest and highly sophisticated medical equipments and other facilities Indian Eye Care hospitals definitely makes for the best choice when it comes to eye care. Your eyes are the most beautiful and most precious part of your body. You can enjoy the beauty of the nature, art people, and architecture through these eyes. So, you need to protect your eyes and have clear vision to the world. Cornea transplant hospitals abroad

We Care India said...


Since
Eyes
are the most important organ of a human body and so vision is the priceless gift of nature. Many ignore to care for their eyes in regular ways and ultimately require going for eye treatment or even go up to surgery level. The other terms of "eye surgery" are "ocular or Orogolomistician surgery". This type of surgery is typically done on the adnexa of an eye or on the eye by an ophthalmic surgeon.
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We Care India said...

Lasik or laser-assisted in situ keratomileusis (LASIK) is a kind of eye surgery, where the patient has to undergo a laser eye treatment process, in which his/her cornea is re-shaped to proffer better sight. To get rid of eye sight related issues, and to get rid of glasses, there is nothing better than Lasik eye treatment. And as we all know, medical science has been progressing in an unmatchable speed, and if thoroughly evaluated and performed, Lasik can help you to enjoy spectacle less life. In most cases, after undergoing Lasik, patient doesn't need to wear glasses. But if the patient is above 40, he/she may need to wear reading glasses that too if both eyes were corrected for clear distance vision.
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We Care India said...

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Nichole Mercado said...

I've first heard about the man who sees through OOKP from my eye doctor at Arizona retina specialists Center. Although, this news can truly be considered Ophthalmology breakthrough there is still the concern about the number of qualified surgeons. Will there be a special training program for Eye Surgeons to be qualified to conduct OOKP surgery? Will Ophthalmology Associations require a licensure of every Eye Center who wishes to conduct OOKP? Well, I wish they do.

brain said...

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