Canadian eye surgery could prevent blindness in thousands worldwide

Surgeons at Toronto's Hospital forSick Children have developed a procedure that could preventblindness in patients with corneal anesthesia, a serious but rare disease.

But they neverimagined their treatment could be used to treat thousands of patients worldwide with longforgotten diseases like leprosy.

A team of two plastic surgeons and one ophthalmologist at Sick Kids hasdeveloped anew nerve graft procedure that could return feeling to eyes that have lost all ability tosense pain.

It was supposed to be a highly specialized surgery that would only be used ina small number of kids in Toronto. But to everyone's surprise it quickly piqued theinterest of surgeons in India, Colombia, Argentina, France, China and around theworld.

"There's a big pent-up demand for adults. There's a huge number of people that couldbenefit," says Dr. Asim Ali, who developed the procedure along with Dr. GregoryBorschel and Dr. Ronald Zuker.

Corneal anesthesia happens when the nerve feeding the eye doesn't send pain signalsback to the brain. Without that pain response, patients don't realize that tiny specks of dustand debris are getting into their eyes and scratching their corneas.

Over time, thisseemingly minor damage accumulates and leads to scarring, and eventually permanentblindness.

"Most of the vision loss is from scar, and scar doesn't repair," explains Ali.

A life-ruining problem

The solution to this life-ruining problem came to Borschel after reading reports of asimilar surgeryattempted in the U.S. Surgeons tried to fix theproblem of corneal anesthesia by redirecting a patient's nerves into the affected eye.

Thesurgery was aninvasive 10-hour procedure that required an incision from ear to earacross the top of the head. It had exciting preliminary results, but no one picked it up andits originator retired.

Borschel explains that the procedure they devised at Sick Kids is much easier.

Ratherthan direct nerves across the top of the head, they take a small piece of the sural nervefrom the patient's leg. Then they make a smallincision above the eye that is not affected,attach the nerve to the other nerves of the forehead, and tunnel it under to the skin toreach the affected eye.

Then the nerve is disassembled into tiny nerve bundles calledfascicles that are meticulously attached to the edges of the cornea.

The surgery requires the close co-operation of plastic surgeons like Borschel and Zuker, and ophthalmologists like Ali.

"It's a nice example of what can be achievedwith a small number of committed people," says Borschel. "It's kind of a love storybetween plastic surgery and ophthalmology. Between two plastic surgeons and Dr. Ali,we managed to figure out something that works. It's a nice definitive solution to thisproblem."

A rare but devastating condition

Although it appeared that only a small number of patients would benefitfrom this new technique,the team continued itswork. Explaining thatdrive,Borschelsays,"It'sa rare condition, but when it does occur it's devastating."

Their perseverance paid off when the team's results were presented at the World Societyfor Reconstructive Microsurgery meeting in Mumbai last March. Borschel remembersthat after the presentation some of the Indian surgeonssaid, "Wehave this problem here, and it's often caused by leprosy."

In Canada most cases of corneal anesthesia are either congenital or due to brain tumours.But in the developing world infections are a major cause.

Though diseases like leprosy,also known asHansen's disease,are rarely seen in North America, they affectover 200,000people world wide.

Herpes is another unlikely culprit. "Children can get recurrent herpes;each time they getan episode they can lose sensation [in the eye]," explains Dr. Ali.

"These patients are very difficult to treat, there is no treatment actually," says Dr.Federico Vargas, who came to Sick Kids from Bogota, Colombia for a plastic surgeryfellowship. Vargas' interest was in cleft palates, but when he sawthe procedure he immediately saw the applications.

Luck strikes again

Then luck struck a second time because his colleague Dr. Mariana Cabrera, anophthalmologist who is also from Bogota, was simultaneously doing a fellowship atToronto Western Hospital.

"I was just talking with her about this type of procedure that I was learning here and shesaid, 'Oh my God! That's great because we have lots of patients [with cornealanesthesia] due to herpes infection,' " Vargas recalls.

Since this surgical pair found themselves in the same city at the same time, they bothlearned the procedure in anticipation of their return to Colombia.

Vargas explains that thenew surgery is generating much interest in Latin America. After presenting the techniqueat a Colombian medical meeting, Vargas was asked to present it at The Bolivarian, amedical conference bringing together doctors from several South American countries.

"It's serendipitous," Borschel says as he looks back at the unlikely way this whole storyevolved.

He admits the team never thought for one second their procedure would reachinto the developing world to potentially prevent blindness in thousands of people.

"It'sreally quite interesting how something relatively small like this took off in such a veryshort amount of time."

Christopher Labos is a cardiologist and epidemiologist at the McGill University Health Centre. He is currently a fellow in global journalism at the Munk School of Global Affairs at the University of Toronto.