Pterygium (conjunctiva) - What Is It?
A pterygium is a vascularized lesion of the conjunctiva of the eye that can invade the cornea. It can cause astigmatism and decrease visual acuity. The word comes from the Greek pterys which means “small wing,” or “fin.”
This “fin” appears in the midline of the eye, in the space between the upper and lower eyelids. It has a triangular shape, hence its name, on the temporal side but is more frequent on the nasal side. The condition could affect one or both eyes.
This condition is a lot more frequent in tropical and subtropical climates, and very rare in cold countries. Also, there’s a relation between it and ultraviolet radiation after exposing the eyes to sunlight without protection or filters.
It mainly occurs in farmers, workers and in outdoor jobs because people are more exposed to solar radiation and dust. It seems to also be related to contact with solvents and chemicals.
The dryness of the environment and the presence of wind that accelerates tear evaporation can also promote this condition. In addition, there’s a hereditary component to it and it’s connected to immunological diseases.
Pterygium occurs in individuals between the ages of 20 and 50 and is a lot more frequent in rural environments. This condition is more prevalent in African Americans regardless of gender. Its incidence is also higher in areas with more bright sunshine.
Symptoms of pterygium (conjunctiva)
The symptoms may vary depending on the activity, size, and location of the pterygium.
The active pterygium is a thickened lesion with inflammation. It’s hyperemic (containing an excess of blood) and has a whitish area at the apex of the triangle.
The symptoms produced by active pterygium include:
- Pruritus (itchiness)
- Foreign body sensation
- A decrease in the visual field
- Double vision
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This kind of pterygium is more prevalent in temperate countries, and so its incidence is lower. There’s slower growth and the symptoms are less obvious. It’s mainly a flat lesion without inflammation, without vascularization, and without signs of growth.
The symptoms of this one are either scarce to non-existent. The size of the pterygium is directly proportional to its symptoms. Thus, larger ones occupy more surface of the cornea and, because of this, affect vision more.
Depending on the location, a pterygium that affects the area of the cornea’s visual field has more symptoms. Thus, the symptoms of pterygium are less obvious when it only covers the periphery of the eye.
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Treatment for pterygium (conjunctiva)
- Glasses with ultraviolet filters between 90 and 100% protection index. You must use them in susceptible populations, especially children.
- Wide-brimmed hats
- Medical treatment
For asymptomatic cases:
- Artificial tears
- Eye lubricants
- Topical corticosteroids at low concentrations if there’s inflammation
- Surgical treatment
In symptomatic cases, the only solution is surgery. In general, the pterygium will continue to grow and if it isn’t removed, then the symptoms will worsen. There are various ways to do this:
- Simple exeresis: Here doctors remove the pterygium and let it heal on its own from the conjunctiva. This kind of intervention isn’t recommended because the pterygium appears again in 40 – 80% of cases.
- Simple conjunctival closure: For this one, a doctor will make an excision and suture of the conjunctival edges. Unfortunately, it also reappears in 45-70% of cases, so it’s only recommended in elderly people because it’s less recurrent.
- Conjunctival and limbal autograft: This is the surgical technique of choice due to its lower recurrence. Also because this intervention requires less recovery time and there are fewer relapses. Doctors may suture or close it with a biological fibrin tissue adhesive. The preference in the use of synthetic adhesives over sutures is due to the fact that they are biocompatible. Thus, they produce little to no inflammation and generate neither a foreign body reaction nor incidental death. Also, these are biodegradable.
- Free conjunctival autograft: This technique requires the excision of the head and body part of the pterygium. Then, the surgeon will cover the exposed sclera with conjunctiva taken from the patient. This procedure leads to good results, although not as good as the limbal one.
Adjuvant treatment for pterygium
This treatment is a complement to surgical treatment and can minimize the risk of recurrence:
- Antimitotics: These prevent cell replication and their mission is to cancel or delay the growth of the pterygium tissue. But, even though they reduce the risk of recurrence of the pterygium, they have toxic effects and complications that, at times, discourage their use. The most used one is Mitomycin C.
- Antiangiogenic: These are good for preventing the vascular proliferation that provides nutrients to the pterygium that facilitate its growth and decrease transparency to the cornea, thus making vision difficult. Currently, topical bevacizumab is under experimental clinical use.
- Beta therapy: This one consists of postoperative radiotherapy of the pterygium with beta radiation to reduce its recurrence. This because it inhibits cell mitosis and prevents a recurrence. Its effects are similar to Mitomycin, but there are fewer side effects.
In conclusion, pterygium is a vascularized lesion of the conjunctiva of the eye that can invade the cornea and can lead to astigmatism and decreased visual acuity.