Taking Care of Pterygium

Submit a question to Dr. Ajamian

Answer: The standard pterygium surgery has been a bare sclera excision, a simple procedure in which the pterygium is surgically removed down to the sclera, and then the eye allowed to heal, explains J. James Thimons, O.D, director of Ophthalmic Consultants of Connecti- cut. Because the recurrence rate is around 40%, this procedure is being replaced by newer, more successful techniques.

One of those is the conjunctival autograft. The surgeon removes a portion of the conjunctiva and grafts it over the pterygium excision. The graft comes from under the eyelid, where it has never been exposed to sunlight and isn’t prone to regrowth. “The success rate there is upwards of 90%,” Dr. Thimons says. “But it’s a really complex procedure and submits the patient to a long-term recovery.”

An effective but simpler technique substitutes amniotic membrane for the conjunctival auto- graft. “The advantage of using amniotic membrane is that it’s a much shorter procedure because it comes ready to be implanted,” says A. John Kanellopoulos, M.D., also of Ophthalmic Consultants and associate clinical professor at Manhattan Eye, Ear and Throat Hospital. “It does not involve additional injury to the eye, since you’re not harvesting tissue from there.”

The amniotic membrane incites healthy growth of the epithelium and fights the scar-producing cells that existed there. The chance of recurrence still exists, likely below 5%, says Dr. Kanellopoulos, whose web site describes this procedure and other corneal surgical topics (www.brilliantvision. com). Amniotic membrane grafting already has shown good results for treatment of corneal burns.

Another new procedure uses an injection of mitomycin-C before the surgical removal of the pterygium. Dr. Kanellopoulos says this procedure is only for very aggressive pterygia. In this emerging technique, the surgeon injects a very small amount of mitomycin-C under the pterygium head 2-4 weeks before the surgery. The injection helps regress the pterygium, and in some cases surgical excision is not even necessary, Dr. Kanellopoulos says.

Answer: There are three things the O.D. should monitor:

• Potential recurrence of pterygia. This could happen anytime within the first couple years post-op, but it’s most likely when the patient reduces or completes medical therapy. The factors that spur recurrence are the same as those that incite the pterygium in the first place: UV radiation from sunlight that causes continuous additive injury to the conjunctiva; continuous irritation in the eye, such as a persistent epithelial defect; or continuous exogenous irritants such as dust, particulate matter or dry wind, Dr. Kanellopoulos says.
  
  
• Adverse treatment effects. Because steroids are known to cause intraocular pressure spikes in some patients, you have to pay close attention to IOPs, Dr. Thimons says. The typical post-op regimen of an amniotic membrane graft is TobraDex (tobramycin/dexamethasone) ointment, Ocuflox (ofloxacin) qid and Pred Forte (prednisolone acetate) qid on day one (or two). Discontinue the ointment, but continue with Ocuflox and Pred Forte for about 10 days. When the external surface of the eye heals, discontinue Ocuflox. Keep the patient on Pred Forte qid for a full month, then modify to bid for another month.
  
  
• Change in refraction. Severe pterygium patients may likely have induction of astigmatism. “Once the procedure has been done, the traction that the pterygium created on the cornea will diminish and the patient’s refractive status needs to be evaluated when it’s stable,” Dr. Thimons says. Keep in mind that the incidence of pterygium and recurrence is greater the closer the patient lives to the equator, Dr. Thimons says. u

top