Excision with Amniotic Graft
An example of a pterygium.
A technically more difficult method is to remove the pterygium as above but to then cover the defect with a graft made of amniotic tissue, which is harvested from placental tissue. This tissue has natural healing properties, allowing the eye to recover faster and with less pain, and the risk of recurrence is lower than with simple excision. The graft can usually be attached to the surface of the eye using a fibrin glue and without the need for sutures. Sometimes this technique is performed using a drug called Mitomycin-C, an antimetabolite which blocks scar tissue from forming.
Excision with Conjunctival Autograft
The most technically challenging method is removal of the pterygium with placement of a conjunctival autograft (‘auto’ meaning from the same patient) on the defect. This tissue is harvested from the patient’s own eye, usually underneath the upper lid where the donor site can heal quickly. The conjunctival graft is either sutured in place and/or fibrin glue can be used. If sutures are used they are typically removed in the office about 2 weeks after surgery. This technique has the lowest risk of recurrence.
More commonly used in the past, a small probe tipped with a Strontium-90 radioactive isotope was placed on the operative site to block scar tissue formation. This was generally a safe procedure but there were cases of poor wound healing leading to serious complications. The problem with beta radiation is the inability to measure exactly how much energy the surface of the eye was being exposed to. This has largely been replaced by Mitomycin-C as mentioned above.