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Clinical Update: Cornea
Treating Pterygium: Innovation from Australia
In sun-drenched Queensland, Australia, one out of every 10 people eventually develops a pterygium. But, as is the case in the United States, these wing-shaped growths don’t get much respect. Viewed primarily as an annoyance, pterygia traditionally have been dispatched in a 10-minute surgery and then subjected to minimal follow-up. Given the brush-off with a few snips, these overgrowths of conjunctival tissue often come back, each time a little tougher to treat.
With little fanfare, Lawrence W. Hirst, MD, chief executive officer of Queensland Eye Institute in Brisbane, has developed a surgical technique that, so far, has virtually eliminated pterygium recurrence. Ivan R. Schwab, MD, professor of ophthalmology at the University of California, Davis, witnessed the technique and the procedure’s follow-up firsthand while on sabbatical in Australia. Dr. Schwab is convinced that Dr. Hirst “has it right.”
Not a Trivial Pursuit
Dr. Hirst takes issue with those who don’t take pterygium seriously. He noted that his research indicates that sun exposure in the first 10 years of life is a key determinant of who develops pterygia, followed by the cumulative effects of the sun as the years go by. In many of his patients, a pterygium begins to develop in the teens or 20s.
With treatments used in the past, these young patients might have experienced several recurrences over a lifetime. Moreover, the cosmetic issues surrounding a pterygium are particularly difficult for younger people. With conventional surgeries, the pterygium recurrence rate now ranges from 5 to 10 percent. Bare scleral excision—though rarely used by itself now —is the exception. The bare scleral approach alone produces recurrence rates as high as 60 to 80 percent, and the pterygium often comes back larger than it was the first time. Dr. Hirst, who reviewed the literature on the treatment of pterygium in Survey of Ophthalmology1 said he considers bare scleral surgery to be a “heinous surgical treatment with no redeeming features.”
A Short History of Pterygium Treatment
When it became clear that bare scleral surgery alone was producing an unacceptable recurrence rate, practitioners turned to adjunctive therapies.
Radiation. Radiation was the first adjunctive therapy used with the simple bare scleral excision. Applied with a plaque of strontium 90, radiation did reduce the recurrence rate to about 10 to 12 percent. The problem was that no one had followed the radiation-treated patients long enough to detect possible long-term complications. When Dr. Hirst’s group reviewed 1,000 cases, they found that 12 percent of these patients had developed scleral necrosis in the area where the radiation was applied. In addition to the pain associated with this complication, a small number of patients had developed potentially sight-threatening endophthalmitis.
Chemotherapy. The chemotherapy agents thiotepa and mitomycin C (MMC) were used next. Today, MMC has supplanted thiotepa and is used most often as an application to the scleral bed after the pterygium has been excised. But MMC is a radiomimetic drug, with actions similar to those of radiotherapy. Although it does bring the recurrence rate down to about 5 percent, Dr. Hirst worries about the long-term complications.“We already know that mitomycin used for other indications can cause significant problems,” he said. “It is quite possible that we could be facing an epidemic of problems in 20 years’ time. There have been very few long-term studies of mitomycin used for pterygium that have followed patients for more than 10 to 15 years.”
In discussing these adjunctive therapies, Dr. Hirst noted the irony of pterygia being considered “trivial” problems but then being managed with adjunctive treatments that could potentially threaten a patient’s sight. The logical approach, he added, would be to use a safe method that reduces the recurrence rate to the same degree as the MMC does but is unlikely to result in long-term complications.
Autoconjunctival transplant. A procedure that fulfills the above criteria is the autoconjunctival transplant (or conjunctival autograft). In this technique, conjunctival tissue is transplanted from the superior limbus to the excision bed, with the graft held in place with either stitches or tissue glue. Autoconjunctival transplants have been used for nearly 30 years and have a recurrence rate of between 5 and 10 percent. Although this is considered to be a reasonable recurrence rate, Dr. Hirst doesn’t agree.
As a result, he has spent the last five to seven years making significant modifications to the procedure—modifications that have reduced the recurrence rate to nearly zero.
Bigger Excision, Better Results
Dr. Hirst’s approach to pterygium removal is to expand the size of the excision and the transplant. He noted that in the traditional surgery, the average piece of transplanted tissue is 4 or 5 mm by 3 or 4 mm. “My observation is that this results in a very poor cosmetic result. There is always a lot of scarring and redness in the area, and the recurrence rate is around 5 to 10 percent.”
In the modified procedure, the surgical defect is approximately 15 mm by 12 to 13 mm, with an equal-sized graft to close the defect. Dr. Hirst extensively removes the subconjunctival tissue—the tissue that he suspects is responsible for the recurrences. “The principle is a large conjunctival Tenon’s excision and an enormous graft.”
Almost PERFECT. In a series of nearly 200 consecutive cases treated with the modified technique, Dr. Hirst has had only one recurrence. “We did the pivotal study a number of years ago, showing that if you want to be fairly secure in identifying a recurrence, you need to follow your patients for at least a year. That’s where many studies fall down, with a lot of patients lost to follow-up.” His study now has a year’s follow-up on more than 95 percent of the patients.
“The cosmetic result is just excellent. In fact, by the end of a year, patients cannot remember which eye they’ve had surgery on,” Dr. Hirst said. “With tongue in cheek, my acronym for the procedure is ‘PERFECT,’ for ‘Pterygium Extended Removal Followed by Extended Conjunctival Transplant,’ although I’m reluctant to use that with patients. I’m a conservative surgeon, and the idea of telling any patient they are getting a perfect procedure bothers me.”
How does he explain the success of the modified procedure? “The extensive dissection and removal of the subconjunctival tissue is probably the reason for the low recurrence rate, and the larger transplant is almost certainly the reason the cosmetic result is so good. I can hide the healing lines under the upper lid, the lower lid and the semilunar fold,” he continued. “I then put my incision line back there under the semilunar fold, and you wouldn’t know it was there. As well as that, the conjunctival graft is adherent to the underlying sclera, so there is very little abnormal vascularization.”
“After seeing what he is doing with pterygium, I realized that I and most of North America have been wrong,” Dr. Schwab said. “He has what has to be the absolute best technique and the best results.”
Financial reimbursement for the new procedure is the main sticking point. Dr. Hirst acknowledges the difference between health care in Australia, with its universal coverage, and health care in the United States. But even in Australia, reimbursement can be an issue. The problem is that the reimbursement is low, but it takes about an hour to perform the procedure.
“Because pterygium has been treated as a trivial condition—an office procedure with a bit of radiation or mitomycin —Australia’s Medicare reimburses very little for it,” Dr. Hirst said. “Even ophthalmologists themselves, who aggressively try to get increased remuneration for cataracts, haven’t even bothered to go after increased remuneration for ptergyium surgery. It’s difficult to change government opinion when they have been told by all the leading authorities that this is a small, simple procedure.”
Patients have to decide what it’s worth to them to have their pterygia removed in a manner that produces the best cosmetic results and has almost no risk of recurrence, Dr. Hirst added. Another important point is that if a patient has had a pterygium removed inappropriately or has a recurrence, the procedure takes longer. Dr. Hirst now has a series of 70 patients who were referred to him for removal of a recurrent pterygium, some patients with as many as five recurrences.
“I use exactly the same technique, but it takes me an hour and a half to two hours because there is so much scarring. Yet I have not had a single recurrence in these 70 patients. So this method works.” The only complication observed in these 70 surgeries for recurrences was persistent strabismus in two patients. In addition, the cosmetic results are not as good as those achieved in a primary surgery.
“It’s like a lot of things in this world —your first go is your best go,” Dr. Hirst said. “And when you are treating pterygium the first time, you have to keep in mind that the last thing you want to see is a recurrence.”
1 Surv Ophthalmol 2003;48:145–180.
Drs. Hirst and Schwab report no financial interests related to this story.