Katherine Harmon writes in Scientific American that a Mississippi woman blind for the past nine years can see 20/70 after one of her own teeth was surgically implanted in one of her eyes:
http://www.scientificamerican.com/blog/60-second-science/post.cfm?id=an-eyetooth-for-an-eye-a-rare-trans-2009-09-17
Image: U.S. Department of Health and Human Services
To begin the months-long process, doctors removed one of Thornton's canine teeth—aka an eyetooth—along with part of the jaw and cut it all down to a shape small enough to replace the cornea. The doctors then drilled a hole into it to insert a lens. In order for the tooth to bind to the lens sufficiently, the implant spent a couple months in the patient's body. In Thornton's case, it was implanted near her shoulder.
To prep the eye to receive the tooth and lens, the doctors placed a cheek graft over the eye to promote moisture. The final tooth-lens product was removed from Thornton's shoulder and placed in the center of the eye, in line with the retina.
The MOOKP procedure was developed in Italy in 1963, and has been more common in Europe and Asia, but only about 600 operations have been undertaken. Given the small number of treatments, its safety remains unconfirmed, and other doctors have their reservations. "It requires a sizable team and several operations," Ivan Schwab, of the American Academy of Ophthalmology, told CNN. "It's just an extreme variation on techniques we're already doing."
http://www.scientificamerican.com/blog/60-second-science/post.cfm?id=an-eyetooth-for-an-eye-a-rare-trans-2009-09-17
Image: U.S. Department of Health and Human Services
They use the tooth because its rigid and doesn't tend to reject, They were using polymers for a while and were having issues with that... and rejection usually means the loss of the eye.