What Is a Pterygium?

Patients notice a pink or fleshy triangle of tissue growing on the white of the eye, often on the side nearest the nose, and worry that it is a tumor or that it will keep growing over the pupil and blind them. It may look red and feel gritty, and it can be a cosmetic concern. They want to know what it is, whether it is dangerous, and whether it needs to be removed.

A pterygium arises from the conjunctiva, the thin membrane covering the white of the eye, and consists of overgrown surface tissue with tiny blood vessels, which is why it can look pink and inflamed. It typically forms on the nasal side and grows slowly in a wing shape toward, and sometimes onto, the cornea.

While it stays on the white of the eye, a pterygium mainly causes irritation, redness, and dryness. The concern arises when it advances onto the cornea. Because it pulls and flattens the corneal surface, it can create astigmatism that blurs vision even before it reaches the center, and if it grows far enough to cover the pupil, it directly blocks sight. It can also leave scarring on the cornea. For most people, though, a pterygium remains a nuisance rather than a threat to vision.

Pterygia are thought to result from chronic ultraviolet light exposure that damages the surface tissue, which is why they are far more common in people who live in sunny climates and work or play outdoors, and why they are nicknamed surfer's eye. Wind, dust, and dryness contribute as well. They usually grow slowly over years and often flare with redness and irritation when exposed to sun, wind, or dry conditions.

As a pterygium enlarges, it flattens the cornea along its axis and induces astigmatism, which can blur or distort vision even while the growth is still short of the center. A large one can extend over the pupil and obstruct vision outright, and it may cause scarring or restrict eye movement in extreme cases. A related but separate growth, a pinguecula, is a yellowish bump that stays on the white of the eye and does not invade the cornea; a pterygium is essentially a pinguecula-like process that has crossed onto the cornea. Because it is UV-driven, sun protection is central to slowing growth and preventing recurrence.

A pterygium is benign, so serious problems are uncommon, but seek evaluation if:

• The growth is advancing toward or across the center of the cornea, or your vision is blurring or distorting.
• It becomes persistently red, painful, or increasingly inflamed.
• It grows rapidly, changes color, bleeds, or looks unusual, since other lesions of the surface, including rare cancerous ones, can mimic a pterygium and must be distinguished.

While most are simply monitored, a growth affecting vision or a lesion that looks atypical is a reason to be seen.

Diagnosis is usually made by examining the growth at the slit lamp, where its characteristic wing shape, location, blood vessels, and extent onto the cornea are assessed. The doctor measures how far it has encroached on the cornea and checks your vision and refraction for induced astigmatism. Corneal topography can map the astigmatism the pterygium is causing, which helps decide whether it is affecting vision enough to warrant removal. Photographs may be taken to document size over time and to track growth. If a lesion looks atypical or is growing unusually, the doctor considers other diagnoses and, when appropriate, a biopsy.

Many pterygia need only conservative care. Sun protection with wraparound UV-blocking sunglasses and a hat slows growth and reduces flares, and artificial tears or short courses of anti-inflammatory drops relieve redness and irritation. Surgical removal is considered when the pterygium threatens or affects vision, is chronically inflamed and uncomfortable, restricts eye movement, or is a significant cosmetic concern. Modern surgery removes the growth and covers the bare area with a graft of the patient's own conjunctival tissue, which substantially lowers the chance that it grows back compared with simply excising it. Even after successful removal, ongoing sun protection is important to reduce the risk of recurrence.

• Do not skip UV protection; sunglasses and a hat are the main way to slow a pterygium and prevent recurrence.
• Do not assume every growth on the eye is a harmless pterygium; an unusual or fast-changing lesion needs to be evaluated.
• Do not rely on long-term steroid drops on your own to keep it quiet, since prolonged steroid use has its own eye risks.
• Do not rub the irritated eye, which adds to inflammation.
• Do not pursue removal expecting a guaranteed permanent fix, since pterygia can recur, especially without sun protection afterward.

Call for an evaluation if a growth on the white of your eye is enlarging, reaching toward the cornea, blurring your vision, or staying red and irritated despite lubrication. Patients in the Hanover area can have it examined and monitored, with removal offered when it is warranted. Have any rapidly changing or unusual-looking spot on the eye checked promptly to confirm what it is.

A pterygium is a benign, sun-related fleshy growth that spreads from the white of the eye toward the cornea and is not cancer, though it can blur vision if it advances far enough. Protect your eyes from UV light and have a growing or vision-affecting pterygium evaluated at May Eye Care Center.