Introduction
Pterygium is a condition of the eye where there is fibrovascular growth of tissue in the conjunctiva (the thin clear membrane that covers the inner portion of the eyelid and the white part called the sclera of the eye), which gradually spreads to the cornea (a transparent membrane which covers the front part of the eye). This layer can be removed only by surgery, but the recurrence rate is 89 %. Recurrence depends on the type and size of pterygium, age of the person, surgery technique, environmental factors, Genetics, and post-operative trauma and inflammation. Treatment for pterygium using platelet-rich fibrin membranes, which is a new generation platelet concentrate that can help in faster healing, better hemostasis, mild postoperative inflammation, and low rate of recurrence.
What Is Pterygium?
Pterygium is a benign inflammatory degenerative condition of the eye surface, where tissue grows along with blood vessels in the conjunctiva and spreads to the cornea. It is triangular and grows toward the nasal area or temporal area; when it is affected in both eyes, it's called bilateral pterygium. It occurs as a result of activation of the tissue growth factors, which causes cell proliferation and angiogenesis (blood vessels formation) therefore, the cornea is invaded by fibroblasts, and even after treatment, it can recur due to the reactivation of inflammatory cells. It is associated with dryness, burning, and itching; the tissue can cover the cornea, causing vision problems.
What Are the Causes of Pterygium?
The causes of pterygium are:
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Environmental factors such as exposure to ultraviolet radiation, windy or dusty atmosphere, and hot and dry weather.
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Outdoor lifestyle.
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Genetics.
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Irritants like wind, smoke, or dust.
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Viral infections such as human papillomavirus and herpes simplex virus.
What Is the Treatment of Pterygium?
Medical treatment for short-term comfort and relief can include artificial tear drops like Loteprednol or topical NSAIDs (non-steroidal anti-inflammatory drugs). But the preferred treatment for pterygium is surgical removal. The techniques include:
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Avulsion Technique: The scleral portion of pterygium on the bulbar conjunctiva is excised with scissors, and the portion is removed by blunt dissection (careful separation of tissues and tissue planes). The recurrence rate is 23 % to 75 %.
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The Bare Sclera Technique: Involves the excision of the head and body of the pterygium and allows the bare scleral bed to re-epithelialize. The recurrence rate was 32 %; when intraoperative Mitomycin C was applied, there was a decrease in the recurrence rate.
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Primary Closure: Involves the excision of the head and mid-body of the pterygium, followed by a tenonectomy (removal of the tendon), then the conjunctiva is carefully closed.
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Use of Conjunctival Autograft: In which a part of conjunctiva from the temporal side of bulbar conjunctiva of the same eye or other eye is taken and sutured on the site of excised pterygium. Instead of conjunctival autograft, autologous (taken from the same individual) blood fibrin, platelet-rich fibrin membrane, or amniotic membrane grafting can be used as an alternative. Amniotic membrane grafting includes using an amniotic membrane in the excised area. It has anti-inflammatory properties, such as suppressing growth factors and encouraging epithelial growth. Therefore helps in healing and reducing recurrence levels. Complications included corneoscleral dellen (ulcer of corneoscleral), graft edema (swelling), epithelial cysts, suture granuloma, bleeding, medial rectus muscle (helps in movement of the eye to the medial side) injury, perforation of the eye globe with the suture needle, complications of grafts like the size of the graft (thick graft), improper placement, graft necrosis, or graft retraction, scleral necrosis, infectious scleritis, and iritis.
To reduce the recurrence rate, conjunctival autograft (CA) with Cyclosporine 0.05 % eye drops and other agents (antimetabolites) such as Mitomycin c and 5-Fluorouracil is used, which inhibits DNA synthesis resulting in cell death. For further reduction in recurrence rate, blood-derived products such as platelet-rich fibrin membranes are used, which can improve wound healing, epithelial regeneration, and hemostasis.
What Is a Platelet-Rich Fibrin Membrane?
It was first developed in France by Choukron et al. It’s anew-generation platelet concentrate that helps in faster healing which is derived from the patient’s blood. It is a fibrin matrix with platelets, cytokines, leucocytes, and circulating stem cells; it contains 95 % of platelets. It has all the favorable growth factors for immunity and healing. Platelets contain growth factors such as epidermal growth factor, transforming growth factor, fibroblast growth factor, vascular endothelial growth factors, platelet-derived growth factors, insulin-like growth factors, and cell adhesion molecules like fibrin, vitronectin thrombospondin, fibronectin, and cytokines. When the matrix degrades at the injury site, it releases epitheliotropic factors, which help in wound healing by increasing cell proliferation and adhesion. They also have anti-inflammatory, antimicrobial, and anti-fibrotic properties.
How Is Platelet-Rich Fibrin Membrane Obtained?
Venous blood (deoxygenated blood) is collected around 5 ml in a vacutainer tube without anticoagulant, then centrifuged for ten minutes, which settles into three layers, those are, cellular plasma (upper layer), fibrin clot (middle part) and red blood cells (lower part), the fibrin clot which is collected 2 mm below the bottom collecting line is called as platelet-rich fibrin. The success of obtaining platelet-rich fibrin depends only on the speed of collecting blood and centrifuging it. The Platelet-rich fibrin membrane can be used for over a week; almost 30 % of the growth factor's natural fibrin framework properties allow it to keep its activity longer.
What Are the Advantages of Platelet-Rich Fibrin Membrane?
The advantages of platelet-rich fibrin membranes are;
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Helps in wound healing.
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Growth and maturation of bone.
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Hemostasis (stopping of blood).
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Epithelial regeneration.
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It can be used as a platelet gel or membrane along with bone grafts, which helps increase bone density.
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Shorter surgical time.
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Mild postoperative inflammation.
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No suture reaction.
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Low rate of recurrence.
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Easy to use and less costly.
Conclusion
Treatment for pterygium includes using grafts such as conjunctival grafts, amniotic membrane grafts, and platelet-rich fibrin membranes. Platelet-rich fibrin membranes are a new-generation platelet concentrate that helps in faster healing. It is derived from the patient’s blood which is easier to use, cost-effective and has shown promising results as it favors wound healing and has a low recurrence rate.
