A PTERYGIUM is a “wing” of scar tissue that grows over the transparent cornea of the eye. Pterygia are thought to be induced by sun and wind exposure. (UV-B radiation can cause mutations in the p53 tumour suppressor gene facilitating abnormal proliferation of the limbal epithelium.) Pterygia can cause visual loss because they are opaque, and due to astigmatism (warping of the cornea so that light rays are no longer focused well). Pterygia may also cause ocular irritation. Small pterygia can sometimes be observed if the patient desires. Frequent lubricating drops and sunglasses are advised to prevent pterygium progression, whether or not the patient wants surgery. Larger pterygia usually require surgical excision if vision is to be preserved.
SURGERY: Pterygium surgery is generally performed with the patient awake using local anesthesia. A microscope/surgical light is employed, and the patient may find the light very bright at first. The patient can help the surgeon by looking in certain positions when instructed. Grafts such as amniotic membrane, or conjunctiva from the non-sun-exposed conjunctiva underneath the patient’s eyelid are usually used. Options for attaching the graft include: stitches, fibrin glue (a blood derived product with potential risk for transmission of viral and prion disease), and “autoblood” graft fixation.
RISKS OF SURGERY:
If a graft is used, the graft may occasionally dehisce (fall out), especially if sutures are not used.
Regrowth of pterygium is the main nuisance following surgery. If the lesion is simply cut out with no other special measures, the recurrence rate may be 50% or higher. If a graft (conjunctival autograft or amniotic membrane) is placed over the scar site, and medications such as intraoperative mitomycin is used, the long term recurrence rate may be lowered to about 17%. As with anything in life, pterygium surgery has potential risks. Although uncommon these risks include the remote possibility of permanent vision loss, uncontrolled infection / bleeding, injury to the muscles that move the eye, perforation of the globe, prolonged discomfort, and untoward reactions to the eye drops.
Mitomycin may occasionally cause a thinning of the white layer of the eye (the sclera) and patients should be aware of this possibility before using the drop. Mitomycin is an expensive solution and only available from certain pharmacies.
Steroid eye drops are required following surgery, and have the potential to cause a short term elevation of the intraocular pressure, and the risk of slightly accelerating cataract formation.
WHAT TO EXPECT FOLLOWING SURGERY: The eye is patched overnight, but can be removed earlier if the patient finds it very uncomfortable. The eyemay be red and irritated for the first 1-2 weeks. Frequent lubricating dropsare recommended in addition to theprescription eyedrops. You can take showers with your eyes closed the day of the surgery, but avoid swimming for a month.
You can return to work the next day, but avoid dusty, dirty environments. You will need post-operative checks 1-7 days after surgery and about 2 weeks later. You may be seen more frequently if you are on special drops. If a graft is placed, stitches may need to be removed arbout 2 weeks after surgery. Prescription eyedrops (e.g. Tobradex, Predforte) are required for about two months. Use the non-prescription lubricating drops (e.g. Refresh Liquigel, Celluvisc) in both eyes indefinitely, to prevent the further formation of pterygia. Do NOT touch your eyeball with a kleenex. Sunglasses should be worn when outside.