Now Thornton, the first recipient of a modified osteo-odonto-keratoprosthesis (MOOKP) in the United States, is a believer in miracles and a beacon of hope for patients around the world blinded by severe corneal scarring.
The 60-year-old grandmother is reading newsprint and boasting 20/60 vision in her left eye just two weeks after undergoing MOOKP at the Miller School’s Bascom Palmer Eye Institute, the nation’s No. 1-ranked eye care center and the first here to use a tooth as a platform for a prosthetic lens implanted in a cloudy cornea.
“Thanks to these doctors I can go home and see my children and my grandbabies,’’ Thornton said during a news conference that drew media attention from around the world. Her vision is expected to improve even more as her surgical scars heal. “It’s like Christmas every day.’’
A former restaurant manager from Smithdale, Mississippi, Thornton was left almost completely blind nine years ago by Stevens-Johnson syndrome, a rare and serious skin disorder that destroyed the cells on the surface of her eyes, leaving them severely scarred. Her right eye could make out light and shadows, but the left one saw nothing but blackness.
Victor L. Perez, M.D., a cornea specialist and associate professor of ophthalmology who brought the MOOKP technique pioneered in Italy to the United States, said the procedure could help a select group of patients who are blinded by chemicals, thermal burns or immunological disorders such as Stevens-Johnson, as well as a growing number of soldiers wounded overseas.
He said corneal blindness from such injuries is particularly frustrating because the internal structure of the eye still works, but the outer cover is so dry and clouded by scars, vision is blocked.
‘This is the best technique available right now to treat corneal blindness for this population of patients,’’ Perez said.
The leader of Thornton’s surgical team, he completed the multi-step surgery September 4, but the complex process began six months earlier when Yoh Sawatari, D.D.S., assistant professor of clinical surgery in the Miller School’s Division of Oral and Maxillofacial Surgery, extracted Thornton’s eye tooth and the surrounding bone.
He and Perez then shaved and sculpted the tooth and bone into a table-shaped platform, drilling a hole in the middle to hold a transparent cylindrical lens created by Jean-Marie Parel, Ph.D., research associate professor of ophthalmology.
Once the 1/8-inch lens was firmly inserted in the hole, the entire prosthetic package was implanted in a subcutaneous pouch of Thornton’s skin for several months, allowing it to “bio-integrate” or fuse into one unit.
In the meantime, doctors prepared the surface of Thornton’s eye for the prosthesis. First, they removed the scar tissue surrounding the damaged cornea; then they used a layer of oral mucosa, taken from Thornton’s cheek, to cover and rehabilitate the bone-dry surface of her eye. Organically similar to a normal eye’s surface, the mucous membrane in the mouth provides a nurturing environment for the tooth — like turning a desert into a garden, Perez said.
In the last phase of surgery, the prosthesis was retrieved from the skin pocket and inserted into the cornea, through a flap made in the mucosa. Like a telescope, the lens protrudes slightly from the eye surface, allowing light to enter and Thornton to begin seeing as soon as her bandages were removed.
Her first sight: the color of the antibiotic Perez dropped into her eye.
“I said, ‘It’s yellow!’’’ Thornton recalled. “I knew I could see and it’s wonderful.’’
A patient at Bascom Palmer for the past six years, Thornton was referred to Perez after being ruled out as a candidate for a more common cornea transplant. The timing was fortuitous. At the time, Perez was exploring the MOOKP procedure and went to Europe last year to train under Italian ophthalmologist Giancarlo Falcinelli, M.D., who modified the original procedure invented by an Italian professor, Benedetto Strampelli, M.D., in the 1960s.
A long-term study of 181 patients documented positive anatomical and functional results in patients with severe corneal scarring. The study was published in October 2005 in the Archives of Ophthalmology.
“Through the work of Dr. Perez’s team, patients in the United States now have access to this complex surgical technique, which has been available only in a limited number of centers in Europe and Asia,” said Eduardo C. Alfonso, M.D., chairman of Bascom Palmer and professor of ophthalmology.