|
Pterygium (pronounced "tur-RIDGE-ium") is a benign thickening of the outer
coating (conjunctiva) of the eye that grows onto the cornea. As a pterygium
grows, it may become red and irritated. Eventually, it may cause visual
disturbances by disrupting the normally smooth surface of the cornea. In
severe cases, a pterygium can block a patient's vision altogether.
An abnormal growth of tissue on the conjuctiva, the clear membrane that
covers the white of the eye, and the adjacent cornea, the clear front
surface of the eye.
Causes of Pterygium. UV radiation (usually from sunlight) is the most common cause of pterygium.
This explains why pterygium occurs with increasing frequency in climates
approaching the equator. Other causes include continuous exposure to dry,
dusty environments. People who spend significant time in water sports
(surfing or fishing) are particularly susceptible to pterygium because of
the intense exposure to UV that occurs in these environments. When the eye
is continuously assaulted by UV rays, the conjunctiva may thicken in a
process similar to callus formation on the skin. The sensitive structures of
the outer eye often can not comfortably tolerate this degenerative process,
and irritation, redness, foreign body sensation, and ocular fatigue can
result.
Preventing Pterygium. The best method of preventing pterygium is to regularly wear UV 400 rated
sunglasses when outdoors in sunny conditions. Sunglasses with a wrap-around
design provide better protection than those with large gaps between the
sunglass frame and the skin around the eyes. Wearing a hat with a wide brim
provides valuable additional protection.
Treating Pterygium. In mild cases, pterygium redness and discomfort can be controlled with
lubricant eye drops (artificial tears). When symptoms of redness,
irritation, or blurred vision are resistant to conservative treatment, or
when vision is affected by progressive growth of a pterygium, surgery is
considered.
History of Pterygium Surgery. In pterygium surgery, the abnormal tissue is removed from the cornea and
sclera (white of the eye). Over the years, pterygium surgery has evolved
significantly, and modern pterygium surgery has a significantly higher
success rate than conventional surgery.
In traditional "bare sclera" pterygium removal, the underlying white of the
eye (sclera) is left exposed. Healing occurs over two to four weeks with
mild to moderate discomfort. Unfortunately, the pterygium may grow back in
up to 50% of patients. In many cases, the pterygium grows back larger than
its original size.
Traditional "bare sclera" pterygium surgery has a high rate of re-growth.
Occasionally, the pterygium grows back larger than the original.
Over the years, surgeons have used several different techniques to lessen
the likelihood of pterygium recurrence, including radiation treatment and
the use of "antimetabolite" chemicals that prevent growth of tissue. Each of
these techniques has risks that potentially threaten the health of the eye
after surgery, including persistent epithelial defects (ulceration in the
surface of the eye), and corneal melting.
Conjunctival Autograft with Stitches. Most cornea specialists today perform pterygium surgery with a conjunctival
autograft because of a reduced risk of recurrence. In this technique, the
pterygium is removed, and the cornea regains clarity. However, the gap in
the mucous membrane (conjunctiva) tissue, where the pterygium was removed,
is filled with a transplant of tissue that has been painlessly removed from
underneath the upper eyelid. Although the procedure requires more surgical
skill than traditional surgery, this "auto-graft" (self-transplant) helps
prevent re-growth of the pterygium by filling the space where abnormal
tissue would have re-grown.
In conventional autograft surgery, stitches are used to secure the graft in
place on the eye. These can cause discomfort for several weeks.
The autograft is held in place with tiny stitches that may dissolve after a
few weeks or can be removed in the surgeon's office. Stitches on the eye
frequently cause discomfort, however, after pterygium/autograft surgery. The
desire for a quicker, more painless recovery has led to the development of
no-stitch pterygium/autograft surgery.
No-stitch Pterygium/Autograft Surgery*. No-stitch pterygium/autograft surgery allows most patients to return to work
within one or two days of surgery.
Technique for No-stitch Pterygium/Autograft Surgery. In no-stitch surgery, the patient is lightly sedated to ensure comfort, and
the eye is completely numbed, so there is no way to see the surgery
occurring and no sensation of discomfort. The abnormal corneal tissue is
removed and replaced with a thin graft of normal tissue. Over the next 2-3
weeks, the eye gradually returns to a normal appearance.
No-stitch surgery is made possible by the use of modern tissue adhesive.
Composed of clotting proteins normally found in human blood, tissue adhesive
allows the surgeon to secure a conjunctival autograft in seconds rather than
minutes. After about one week the tissue adhesive dissolves with no residue,
leaving the eye to heal comfortably. Although tissue adhesive is derived
from human blood products, no cases of blood borne infection have ever been
reported among millions of patients treated with this material in heart and
lung surgery.
|
