What is pterygium?
A pterygium is a wedge-shaped fibro vascular growth of the conjunctiva (the surface tissue of the white of the eye) that extends onto the cornea. A pterygium often grows in a ‘wing’ shape (pterygos in Greek is wing), which extends across the cornea (baby of the eye) towards the pupil. It most often occurs on the inner side of the pupil although it can be found on either side of the cornea.
Mostly people find something fleshy growing on the transparent part of the eye (cornea) which looks red.
What causes it?
Solar radiation includes visible light and ultraviolet energy which is not visible to the naked eyes but is harmful to the exposed surfaces of the body. The outer surface of the cornea has an outermost layer of cells known as the epithelium. The epithelium on the eye is more sensitive because it does not have the protective coating known as keratin.
If the epithelial cells and the underlying basement membrane are damaged by ultraviolet radiation a healing response is triggered stimulating the growth of new tissue. After the basement membrane is damaged a response similar to scar formation occurs. This ‘drags’ the abnormally thick epithelium across the cornea and stretches the adjacent conjunctiva. This wing-like growth of conjunctiva over the cornea is called a pterygium. Given the same exposure different people will develop different responses due to individual variations in enzyme levels in the tears, among other things. So some people will develop pterygium and many will not, although they are living in the same environment.
What symptoms would I have with a pterygium? Small pterygium are often asymptomatic, and do not require immediate attention. Most of the problems are cosmetic. However, some become red and inflamed from time to time and this leads to pain, redness and irritation in the eye. Large or thick pterygium may bother some people due to a persistent foreign body sensation in the eye. Constant pulling of the cornea by a pterygium may require a change in the prescription for glasses, or glasses may be needed where they weren’t before. When a pterygium encroaches on the papillary area it starts affecting the vision. Very extensive pterygium may lead to extremely poor vision.
What is the treatment?
Once the pterygium is in place, surgery is the only answer. Eye drops can halt the progression but cannot reverse the situation. So for those who want to get rid of the pterygium because of symptoms or for cosmetic reasons, surgery is the only answer.
What does Pterygium surgery involve?
The surgery is a day-care procedure. Mostly it is done under local or topical anaesthesia. The pterygium is dissected from the underlying layers of the cornea, the surface smoothed out, and the blood vessels cauterized using microsurgical techniques.
This leaves a bare area of cornea where the ‘wing’ was removed, and a bare area of sclera (white of eye) where the ‘root’ was removed. The remaining tissue has a thick edge. This is undermined to avoid a visible ridge in the healed eye and then a conjunctival graft/amniotic membrane is applied in cases where this is required. The small pterygium does not need a graft in older people, but some pterygium do need a graft.
There might be the use of additional medication like Mitomycin C if the surgeon chooses.
When is the best
time to operate?
If a pterygium grows across the pupil as in the picture above, you have already left it too late to save clear vision. Beneath the pterygium is a scar which may be quite deep and cannot be completely removed without leaving the cornea too thin. If the pterygium is outside the pupil, any faint remaining scar that is not cosmetically visible is of no importance, but if the remaining scar is in the pupil the vision will be affected permanently. The best time to have a pterygium excised is before it reaches the nearest edge of the pupil. So if you can see it growing, do not wait until it affects your vision permanently; get it removed early.
What are the possible
complications after surgery?
The common complications include regrowth; ulceration within the operated area; and infection
Owing to some environmental factors it is likely that pterygium may recur in the same place. This can be managed by the use of protective glasses and medication. Other complications can be minimized by the proper selection of medication during and after surgery. A change in vision/prescribed glasses is likely if the pterygium extends close to the pupil.
The complications can always be avoided if the eye is protected from irritants and kept well lubricated for six weeks after surgery. For this reason the operation should not be contemplated unless you are prepared to make the lifestyle sacrifices required to ensure a good result is obtained. No amount of surgical expertise can give a good long-term result if the eye is exposed to irritants post-operatively.
What are the options for a recurring pterygium?
Initially a recurring pterygium is treated conservatively for at least 6 months before re-operating. Most of the time re-operation is more extensive than the primary surgery, because it involves more meticulous and deeper dissection than before. During re-operation Mitomycin C, a conjunctival auto-graft and an amniotic membrane can be used as an adjunct.
How do you prevent a
pterygium from developing?
The best treatment is prevention. Wearing wrap-around sunglasses when exposed to sun and wind will prevent a pterygium (as well as skin cancer of the eyelid, and may delay the onset of cataract and age-related macular degeneration).
Besides the ultraviolet exposure, extreme heat and dusty conditions also interfere with the normal eye surface. If the eyes are reddened from a day outdoors, the appropriate action is to use artificial tears frequently and decongestant drops infrequently. Most of the time dry, dusty, hot, sunny environments cause an imbalance in the protective features of the normal surface of the eye and this chronic insult results in the fast progression of a pterygium.
