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PINGUECULA AND PTERYGIUM

Dr. Carolina Valdivia explains the eye conditions pinguecula and pterygium: their causes, symptoms, and treatment

Doctor Valdivia! There is something wrong with my eye!

This is a common complaint that I receive from patients visiting my ophthalmology practice. Eye problems can be annoying and uncomfortable. Fortunately, many common eye (ocular) disorders resolve over time without treatment or can be managed by applying medications, many of which are available over the counter (OTC). Products such as artificial tears, ointments, and ocular decongestants can help with dryness, itching, or excessive watering of the eye. However, treatment choices should be made in consultation with an eye-care professional. This will ensure that you are using the right medication for the right problem.

WHAT ARE PINGUECULA AND PTERYGIUM?

Although the terms pinguecula and pterygium might give the impression that they are rare and exotic medical diseases, in reality each is a common eye condition that typically is benign (not a major threat to health or life). Patients come to my office complaining of a focal red area or lump in the exposed area of the cornea and sclera between the lids of the open eye known as the interpalpebral zone. In some cases, there might have been a previous lesion in the same area of the sclera that the patient may have noticed before.

Pinguecula

Pinguecula are opaque, slightly elevated masses on the conjunctiva that are gray-white to yellow in color. The conjunctiva is a thin membrane that covers the inner surface of the eyelid and the white part of the eyeball (sclera). Pinguecula usually are located in the interpalpebral zone, at the 3-o’clock or 9-o’clock position, and are adjacent to, but do not invade, the cornea. They are common in the tropics and are believed to be related to sun exposure. Pinguecula usually are bilateral (present in both eyes) and are most often found in the interpalpebral zone of the eye closest to the nose, as opposed to the outer edge. The size and appearance of masses varies, but typically they are round or oval with a yellowish hue. They sometimes can lead to the formation of a pterygium.

Although the epithelial layers of the conjuntiva in the interpalpebral zone remain unchanged, two notable alterations occur in the layers beneath. One of these is hyalinization that occurs in a layer just below the epithelium. It consists of degenerating collagen and the presence of a granular material that likely is produced by decomposition of connective tissue components. The other change is that fibroblasts show extensive alteration. Aberrant immature forms of newly synthesized elastic fibers are located under the hyalinization zone. These fibers deteriorate and the normal assembly of elastic fibers is prevented.

Pterygium

A pterygium is a wing-shaped fleshy growth consisting of fibrous tissue with blood vessels that extends from the sclera (white part of the eyeball) to the cornea (the clear front window of the eye). In extreme cases, it can interfere with vision.

As with pinguecula, a pterygium occurs in the 3-o’clock or 9-o’clock position of the interpalpebral zone. However, unlike pinguecula, it crosses the border between the sclera and cornea known as the corneal limbus and is progressive (gets worse over time).

A pterygium consists of three distinct regions. The cap or leading edge is a flat, gray zone on the cornea that is composed primariy of fibroblasts and invades and destroys Bowman's membrane (area directly below the epithelium). A line of iron deposition called Stocker's line may be present anterior to the cap, accompanied by areas of corneal drying or even a dellen (area in which the tear film fails to cover the cornea). Behind the cap is the apex or head, a whitish, thickened vascular region that firmly is attached to the cornea. Trailing the head is the body or tail, a fleshy, mobile, vascular area of bulbar conjunctiva that has distinct edges. Fibrovascular tissue with similar aberrant characteristics to those found in pinguecula is situated beneath the epithelium of a pterygium. An extensive network of blood vessels also is associated with it.

Pinguecula with moderate inflammation

A majority of pinguecula and pterygia grow slowly and do not cause significant problems. Although my patients tend to worry that the lesions might be cancerous, they actually are the opposite. Cancer is characterized by an abnormal growth of undifferentiated cells (a tumor). However, the underlying process behind pinguecula and pterygia is degenerative, a situation characterized by a deterioration of the function or structure of affected tissues in the interpalpebral zone. This usually does not lead to anything deleterious, such as a serious loss of vision or blindness.

WHAT CAUSES PINGUECULA AND PTERYGIUM?

The causes of the lesions are not well understood. However, exposure to ultraviolet and infrared radiation from sunlight has been associated with them. This is supported by the fact that they occur in the interpapebral zones of the cornea and sclera, which are exposed to light. Additionally, individuals that work outside or otherwise spend extended periods of time in the sun are much more likely to have pinguecula or pterygia than those that do not. Environmental irritants, such as dust and wind, also have been implicated.

SIGNS AND SYMPTOMS OF PINGUECULA AND PTERYGIUM

Many people pinguecula and pterygium experience no symptoms at all. In both conditions, the lesion can become irritated and inflamed, causing eye redness and discomfort.

Pterygium showing encroachment into the cornea: (1)
fibrovascular apex, (2) avascular fibrotic cap. Source: Krachmer
JH, Mannis MJ, and Holland, EJ. Cornea: Fundamentals of
Diagnosis and Treatment, 3rd Ed. New York: Mosby Elsevier, 2011.

This usually results from exposure to sun, wind, dust or extremely dry conditions. Some people report feeling that something is in their eye, particularly if the pinguecula or pterygium thickens.

A large and advanced pterygium can distort the surface of the cornea and cause astigmatism. If this occurs or if a pterygium becomes inflamed, surgical removal may be necessary.

PREVENTION OF PINGUECULA AND PTERYGIUM

There is no known method of preventing a pinguecula or pterygium. My best advice is to protect your eyes from excessive sun exposure by wearing protective eye wear with good ultraviolet blockage. At the very least, wear a rimmed hat. Most instances of pinguecula or pterygium do not constitute a serious eye disease. Surgery usually is not necessary.

TREATMENT OF PINGUECULA AND PTERYGIUM

I take a conservative approach in treating most people with pinguecula and pterygium. I usually begin by prescribing artificial tears, which often diminish discomfort and can help alleviate the sensation of a foreign body in the eye. If a lesion becomes inflamed, I prescribe a mild optical decongestant. If it persists, I might consider adding a short course of therapy with an anti-inflammatory agent. However, caution must be exercised, as corticosteriods can cause elevations in intraocular pressure and result in optic nerve damage. I always monitor intraocular pressure throughout the treatment period.

Although surgery is the only way to remove a pinguecula or pterygium, I do not recommend it unless it is causing significant problems with vision, blinking, or contact lens wear. Even with modern techniques, surgical outcomes can be disappointing. This is because the recurrence rate (reappearance of a lesion in the interpalpebral zone) often is as high as 50-60 percent.

Three types of problems may warrant surgery.

If vision is affected by a pterygium large enough to cause astigmatism or involve the central visual zone of the cornea. Surgery may be able to improve the clarity of the optical center and limit excessive or irregular astigmatism.
If a pterygium (rarely a pinguecula) is unattractive and affects a patient's sense of well-being. Surgery can reduce the size of a fleshy pterygium, but complete elimination often is not possible.
If a pinguecula or pterygium causes excessive discomfort due to dryness or a chronic foreign body sensation. Surgery usually improves comfort, but sometimes irritating symptoms may remain.

The surgery is painless. I perform it as an outpatient procedure with local anesthesia. To prevent regrowth after surgical removal of a pterygium, I usually perform a procedure called autologous conjunctival autografting. This involves suturing or gluing a piece of surface eye tissue onto the affected area. This method is very safe and significantly reduces the recurrence rate.

Healing typically requires several weeks. During this period, patients apply topical eye drops or ointments that I prescribe several times a day. In the early phase of healing, the eye may be slightly swollen and bloodshot in appearance. Eventually the surgical site improves in comfort and appearance.

All patients with either of these conditions, or who are at risk for developing pinguecula and pterygium, can benefit from sun protection for their eyes.

REFERENCES:

Chui J, Di Girolamo N, Wakefield D, Coroneo MT. The pathogenesis of pterygium: current concepts and their therapeutic implications. Ocular Surface. 2008;6(1):24-43.

Dong N, Li W, Lin H, Wu H, Li C, Chen W, Qin W, Quyang L, Wang H, Liu Z. Abnormal epithelial differentiation and tear film alteration in pinguecula. Investigative Ophthalmology and Visual Science. 2009;50(6):2710-2715.

Marcovich AL, Bahar I, Srinivasan S, Slomovic AR. Surgical management of pterygium. International Ophthalmology Clinics. 2010;50(3):47-61.

Yanoff M and Ducker JS. Ophthalmology, 3rd Ed. New York: Mosby Elsevier, 2008.

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