Generality
Pterygium is a disease that affects the anterior surface of the eye. This pathological condition is characterized by the development of a fibrovascular membrane at the level of the scleral conjunctiva .
The causes of pterygium development are not yet fully known. The disease is probably favored by sun exposure and chronic irritation of the ocular surface.
Often, the pterygium is evident to the naked eye, but the doctor confirms the diagnosis with a careful examination of the structures involved.
Pterygium can be surgically removed, but this pathology tends to recur with some frequency.
What's this
A pterygium is a disorder located on the ocular surface, characterized by the abnormal growth of the bulbar conjunctival tissue.
The protuberance that is created presents a horizontal course and, after a certain period of growth, tends to invade the cornea on the side of the eye closest to the nose. In some cases, this membrane can also be found on the temporal side of the same eye. The affected portion of the cornea will become whitish and rich in vessels, with a non-regular surface.
In practice, the pterygium resembles a sort of thin cloth or film that grows above the eye.
The term pterigio derives from the Greek " pterugion", that is "small wing of insect", in reference to the aspect with which the disease presents itself.
Pterygium can cause astigmatism of difficult correction with glasses, due to the traction exerted by the conjunctiva.
Causes
A pterygium is a benign (non-cancerous) formation that usually occurs in adult patients; On the other hand, there are very few cases in children. The highest incidence occurs between the ages of 20 and 50 and in males there is a prevalence twice as high as in females.
The causes that induce this change in the normal conjunctival tissue are still not entirely clear. However, it is known that prolonged exposure to atmospheric agents, in particular to wind and ultraviolet and infrared rays from sunlight, contributes to the onset of the disease.
Because of this characteristic, pterygium is found above all in fishermen, mountaineers and other people who spend a lot of time in the sun or work outdoors, without the adequate protection of glasses or hats.
The disease also appears to be favored by chronic irritation of the ocular surface.
Other significant risk factors are represented by:
- Race (Asian, African and South American);
- Spend the first 5 years of life in equatorial geographical areas (note: pterygium is more common in warm climates; in fact, it is frequently found in tropical or subtropical countries).
Pterygium can develop from a pinguecula . This last lesion grows in relief near the cornea, but normally does not involve it (precisely because of this aspect, it is distinguished from the pterygium).
Symptoms and complications
Pterygium develops slowly and progressively on the white part of the eye (sclera), in the nasal and temporal portions of the corneal periphery. This injury may not be associated with specific symptoms.
In some patients, pterygium may become red and inflamed in particular irritating circumstances, such as, for example, rooms filled with smoke, air conditioning, lack of sleep and sunlight.
In case of inflammation, they occur frequently:
- Persistent redness;
- Burning and discomfort in night vision;
- Excessive tearing;
- Diplopia in the side gaze;
- Feeling of having a foreign body in the eye.
If it grows excessively and significantly infiltrates the corneal stroma, the pterygium may interfere with vision by pulling and deforming ( astigmatism ) the cornea.
In the most advanced cases, when the pterygium extends into the optical zone, there is a noticeable reduction in vision ; in this case, the central portion of the cornea located in front of the pupil is covered.
In an extremely small number of patients, pterygium can prevent the eye from moving completely in all directions.
Diagnosis
An eye examination is often sufficient to diagnose pterygium, which is characteristic in appearance and position. The specialist doctor can examine the cornea, the iris and the ocular attachments involved with a slit lamp.
Pterygium can also be seen with the naked eye, as well as with the slit lamp, due to the presence of conjunctival tissue on the ocular surface. This formation typically appears as a triangle, with the apex facing the center of the cornea.
Therapy
The therapy is surgical and involves the removal of the pterygium . This operation is performed on an outpatient basis, with local anesthesia, ie with the infiltration of the drug in the conjunctiva alone or a peribulbar injection.
The surgery is indicated above all in the following cases:
- Non-correctable astigmatism;
- Occlusion of the optical zone;
- Recurrent inflammations not controllable with local therapy;
- Aesthetic reasons.
After the operation, at the point where the pterygium was removed, it may be necessary to take a healthy conjunctiva flap from the same eye or from the other eye and transplant it ( conjunctiva autograft ). To complete the operation, it may be necessary to apply stitches or use a special biological glue (fibrin glue). Generally, recovery takes many weeks and involves applying eye drops or topical ointments prescribed several times a day.
Pterygium removal is often repeated, as the lesion may re-form and cannot be controlled with eye lubricants, nor with local anti-inflammatories.
Other methods of treatment for pterygium are not available, just as there are no medicines capable of preventing their growth.
The best way to avoid repeating the lesion after treatment is to limit exposure to environmental factors that contribute to development (such as direct exposure to sunlight, irritants and dusty environments).
Prognosis
The removal of the pterygium cannot be considered definitive; in fact, this pathology can recur with a certain frequency.
This occurrence is more likely in the following situations:
- Previous eye operations;
- Pterigi doubles (nasal and temporal in the same eye);
- Pterigus fleshy (which does not allow the visualization of the underlying sclera).
In any case, failure to treat can cause an irregular astigmatism that is difficult to correct with glasses.
Prevention of pterygium is essential for those exposed to ultraviolet rays. The use of sunglasses according to the law, in fact, in addition to preventing their appearance, also protects the eye structures from the potential damage of UV radiation (in particular, the retina and the crystalline lens).
