Pterygium is a disease of the ocular surface that occurs on the conjunctiva, characterized by fibrous tissue with blood vessels supplying it. This disease is commonly found in countries near the equator with intense sunlight. Although the exact cause or pathogenesis of pterygium is not clearly understood, certain risk factors have been identified as related and considered causes of the disease. The most important risk factor is the eye’s exposure to Ultraviolet (UV) radiation present in sunlight continuously and for prolonged periods.
Although there are three types of UV radiation, namely UVA, UVB, and UVC, the main cause of pterygium is UVB radiation, which is harmful. It causes cellular and tissue changes and results from direct exposure to sunlight.
Pterygium treatment can be done in various ways
Treatment of early-stage or mild pterygium is usually supportive, involving the use of eye drops and/or topical medications to reduce irritation, itching, pain, swelling, or inflammation, along with wearing sunglasses to help alleviate symptoms and prevent the progression of pterygium. However, if supportive treatment is ineffective, the patient experiences decreased vision, severe pain, swelling or redness, pterygium restricting eye movement, astigmatism caused directly by pterygium, or cosmetic concerns, the doctor will consider surgical treatment.
Currently, there is no clear consensus regarding pterygium excision surgery (pterygium excision, Image 1), including indications for surgery, surgical techniques, adjuvant therapy, types and duration of postoperative treatment, and management of recurrence.
A survey of 199 corneal specialist ophthalmologists using questionnaires, published in the Cornea journal in 2019, found that more than 90% of ophthalmologists perform surgery when the pterygium covers the visual axis, the patient has eye pain or redness from pterygium, the adhesion of pterygium restricts eye movement or causes astigmatism. Only 41.7% perform pterygium excision for cosmetic reasons.
There are several methods of pterygium excision surgery
The first pterygium surgery was performed in 1948 using the bare sclera technique by D’Ombrian. The pterygium and underlying Tenon’s fascia tissue were removed, leaving the exposed sclera uncovered. However, when evaluating surgical success by recurrence rate, this method showed a high recurrence rate of up to 50%. Therefore, in the 1970s, beta radiation was introduced as an adjunct, reducing the recurrence rate to about 12%. Over time, many reports of complications from beta radiation after surgery emerged, leading to its decline in popularity and eventual discontinuation.
In 1985, Kenyon and colleagues introduced a new surgical technique using the patient’s own conjunctiva to cover the exposed sclera, which effectively reduced the recurrence rate further to only 5%. This method has remained popular to the present day.
5 popular methods used in pterygium surgery
Currently, pterygium excision surgery is chosen from one of these five methods:
- Excision of pterygium leaving the sclera exposed (Bare sclera technique)
- Excision of pterygium and pulling the surrounding conjunctiva to the limbus and suturing closed (Simple conjunctival closure)
- Excision of pterygium followed by autologous conjunctival graft transplantation in the excised area (Resection followed by autologous conjunctival graft)
- Excision of pterygium followed by limbal-conjunctival graft transplantation including limbal tissue in the excised area (Resection followed by limbal-conjunctival graft)
- Excision of pterygium followed by amniotic membrane graft transplantation in the excised area (Resection followed by amniotic membrane graft)
In addition to the above surgeries, adjuvant therapies are used alongside the main surgery to enhance effectiveness and reduce recurrence, such as mitomycin-C (MMC), 5-FU, vascular endothelial growth factor (VEGF) inhibitors, and Interferon alfa 2b.
According to the American Academy of Ophthalmology report in 2013, combined with meta-analysis and literature reviews, the recurrence rates are as follows: bare sclera technique 27-88%, bare sclera + MMC 3-40%, conjunctival autograft 2-39%, limbal-conjunctival autograft 0-15%, and amniotic membrane graft 6-41%, respectively.
- Preop = before surgery, the pterygium on the right eye’s nasal side shows intermittent inflammation and redness
- 1 d = 1 day after surgery
- 1 wk = 1 week after surgery, before and after suture removal, the corneal abrasion after surgery has healed normally
- 1 mo = 1 month after surgery, the amniotic membrane appears smooth, clear, and integrates with the surrounding conjunctiva
Postoperative care for pterygium patients
Ophthalmologists prescribe anti-inflammatory steroid eye drops, which may be potent corticosteroids such as prednisolone acetate, dexamethasone, or soft steroids such as fluorometholone, loteprednol, along with antibiotics to prevent postoperative infection. Other eye drops such as nonsteroidal anti-inflammatory drugs (NSAIDs) and cyclosporine A may also be used.
Since steroid eye drops must be tapered gradually after pterygium surgery, the treatment duration is relatively long. Studies show that the duration of steroid use ranges from less than 1 month to more than 3 months, mostly between 1-2 months.
Long-term steroid use may cause side effects such as increased intraocular pressure and subsequent glaucoma. Some patients may be more sensitive to steroids than normal and experience a rapid increase in intraocular pressure even with low doses. Therefore, strict adherence to prescribed medication and postoperative monitoring are essential.
Follow-up visits are not only for monitoring surgical outcomes and preventing postoperative infections but also for observing and preventing ocular hypertension and glaucoma, which can lead to permanent blindness. Continuous use of sunglasses after surgery when outdoors remains necessary to help prevent or reduce recurrence. Recurrent pterygium is usually thicker and redder than before, and repeat excision surgery is more difficult than the first time.
