Pterygium (also known as surfer's eye) is a fleshy triangular growth that can occur on the bulbar conjunctiva of the eye at the 3 and 9 o'clock meridians.[1] It can spread across and distort the cornea, leading to changes in vision. Pterygia can vary in size and severity, from small, inactive lesions to large, rapidly growing ones that can affect the corneal topography. Treatment options include lubricating eye drops, steroids, and surgical removal if necessary. Prevention involves protecting the eyes from UV exposure and monitoring any changes in vision through regular eye exams.[2, 3, 4]
The pathophysiology of pterygium is characterized by elastotic degeneration of collagen and fibrovascular proliferation, with an overlying covering of epithelium. Histopathology of the abnormal collagen in the area of elastotic degeneration shows basophilia with hematoxylin and eosin stain. This tissue also stains with elastic tissue stains, but it is not true elastic tissue, in that it is not digested by elastase.[2, 3]
The incidence of pterygium in the United States and internationally varies with geographic location, with higher prevalence rates seen in lower latitudes where there is increased exposure to ultraviolet light.[1, 5, 6] Prevalence rates in the continental U.S. range from less than 2% above the 40th parallel to 5-15% between latitudes 28-36°.[5, 6] Internationally, studies show a prevalence of pterygium between 1% and over 30%, with a pooled prevalence around 10%.[7] Risk factors for pterygium include age, male sex, outdoor job exposure, low education, rural residence, low income, darker skin complexion, and smoking. The highest prevalence rates are found around the equator, with rates more than 10 times higher than those outside this area, highlighting the significant role of ultraviolet irradiation in pterygium pathogenesis.[8]
United States
The incidence of pterygium within the United States varies with geographic location.[1] Within the continental United States, prevalence rates vary from less than 2% above the 40th parallel to 5-15% in latitudes between 28-36°. A relationship is thought to exist between increased prevalence and elevated levels of ultraviolet light exposure in the lower latitudes.[5, 6]
International
Internationally, the relationship between decreased incidence in the upper latitudes and relatively increased incidence in lower latitudes persists.
A pterygium can cause a significant alteration in visual function in advanced cases. It can become inflamed, resulting in redness and ocular irritation.
Pterygium is reported to occur in males twice as frequently as in females.
It is uncommon for patients to present with pterygium prior to age 20 years. Patients older than 40 years have the highest prevalence of pterygia, whereas patients aged 20-40 years are reported to have the highest incidence of pterygium.
The visual and cosmetic prognosis following pterygium excision is good. The procedures are well tolerated by patients, and, aside from some discomfort in the first few postoperative days, most patients are able to resume full activity within 48 hours of their surgery. Those patients who develop recurrent pterygia can be retreated with repeat surgical excision and grafting, with conjunctival/limbal autografts or amniotic membrane transplants in selected patients.[9, 10]
Patients with pterygium should reduce exposure to ultraviolet light whenever possible. Methods of reducing ultraviolet exposure include wearing ultraviolet-blocking sunglasses, wearing a cap with a wide brim, and seeking shade from direct sunlight.[4]
Patients who are at high risk for the development of pterygium because of a positive family history of pterygia or because of extended exposure to ultraviolet irradiation need to be educated in the use of ultraviolet-blocking glasses and other means of reducing ocular exposure to ultraviolet light.
Patients with pterygia present with various complaints, ranging from no symptoms to significant redness, swelling, itching, irritation, foreign body sensation, and blurring of vision associated with elevated lesions of the conjunctiva and contiguous cornea in one or both eyes.[4]
A pterygium can present as any of a range of fibrovascular changes on the surface of the conjunctiva and the cornea. It is more common for the pterygium to present on the nasal conjunctiva and to extend onto the nasal cornea, although it can present temporally, as well as in other locations.
The clinical presentation can be divided into 2 general categories.
One group of patients with pterygium can present with minimal proliferation and a relatively atrophic appearance. The pterygia in this group tend to be flatter and slow growing and have a relatively lower incidence of recurrence following excision.
The second group presents with a history of rapid growth and a significant elevated fibrovascular component. The pterygia in this group have a more aggressive clinical course and a higher rate of recurrence following excision.
Risk factors for pterygium include (1) increased exposure to ultraviolet light, including living in subtropical and tropical climates,[11] and (2) engaging in occupations that require outdoor activities.
A genetic predisposition to the development of pterygia appears to exist in certain families.
A predilection exists for males to develop this condition in significantly higher numbers than females, although this finding may represent an increased exposure to ultraviolet light in this portion of the population.[11]
Complications of pterygium include the following:
Extensive involvement of the extraocular muscles may restrict ocular motility and contribute to diplopia. In patients who have not yet undergone surgical excision, scarring of the medial rectus muscle is the most common cause of diplopia. In patients with pterygia who have previously undergone surgical excision, scarring or disinsertion of the medial rectus muscle is the most common cause of diplopia.
In patients with significantly elevated pterygia, focal drying and subsequent thinning of the adjacent cornea may rarely occur.
Postoperative complications of pterygium repair can include the following:
Late postoperative complications of beta radiation of pterygia can include scleral and/or corneal thinning or ectasia, which can present years or even decades after treatment. Some of these cases can be quite difficult to manage.
In some cases, adjunctive use of topical MMC at and after pterygium surgery has been reported to cause similar ectasia or melting of the sclera and/or the cornea.[13, 14, 15]
The most common complication of pterygium surgery is postoperative recurrence. Simple surgical excision has a high recurrence rate of approximately 50-80%. The rate of recurrence has been reduced to approximately 5-15% with use of conjunctival/limbal autografts or amniotic membrane transplants at the time of excision.[16, 17, 18, 19]
On rare occasion, malignant degeneration of epithelial tissue overlying an existing pterygium can occur.
Corneal topography can be very useful in determining the degree of irregular astigmatism induced by an advanced pterygium.
External photography can assist the ophthalmologist in following the progression of the pterygium.
Multiple different procedures have been advocated in the treatment of pterygium. These procedures range from simple excision to sliding flaps of conjunctiva with and without adjunctive external beta radiation therapy and/or use of topical chemotherapeutic agents, such as mitomycin C (MMC).[13, 21]
Using free grafts of conjunctiva (with or without limbal tissue) at the same time as primary excision of the lesion has been widely advocated as the preferred treatment modality for aggressive pterygia. For moderate-to-severe pterygia, some corneal surgeons use amniotic membrane transplants. Both the conjunctival autografts and the amniotic membrane transplants may be sutured onto adjacent conjunctiva and subjacent cornea. Some corneal surgeons seal the graft tissue onto the underlying sclera with the aid of fibrin tissue glue rather than with sutures.[16, 22, 23, 24, 25, 26]
A study by Kheirkhah et al found that conjunctival inflammation was much more common with amniotic membrane transplantation than with conjunctival autograft after pterygium surgery. However, with control of such inflammation and intraoperative application of mitomycin C, both techniques brought about similar final outcomes.[27]
To alleviate symptoms of a pterygium, treatment options include artificial tears or short-term use of corticosteroid drops or ointments. Wearing a hat and UV-blocking glasses can help slow the growth of a pterygium. Surgical removal may be necessary for growth control, cosmetic reasons, or vision improvement. Antimetabolites like mitomycin and 5-fluorouracil can reduce recurrence rates but have potential complications. Anti-VEGF injections under a pterygium can prevent progression and improve outcomes, especially when combined with excision and grafting. The most effective technique to prevent recurrence is surgical removal followed by a conjunctival autograft.[4]
Patients with pterygium can be observed unless the lesions exhibit growth toward the center of the cornea or the patient exhibits symptoms of significant redness, discomfort, or alterations in visual function. Pterygia can be removed for cosmetic reasons, as well as for functional abnormalities of vision or discomfort.[28]
Surgery for excision of a pterygium usually is performed in an outpatient setting under local or topical anesthesia with sedation, if necessary.
Several studies have investigated the impact of different surgical techniques and adjuvant therapies on outcomes following pterygium excision.
In a randomized study by Kheirkhah et al, the comparison of MMC application on the perilimbal bare sclera versus subconjunctival MMC administration during pterygium excision with an amniotic graft revealed a decrease in endothelial cell counts in both groups, with the bare sclera group showing less cell loss than the subconjunctival group at the 6-month mark.[29] This study emphasized the importance of precise MMC placement to avoid complications like scleral melts.
Bahar et al conducted a nonrandomized study that evaluated the impact of MMC on endothelial cell loss in patients undergoing pterygium surgery with conjunctival autograft.[30] They found a reduction in endothelial cell counts at 3 months post-surgery in the MMC group compared to the control group, suggesting that MMC application can influence endothelial cell numbers after pterygium excision.
Hirst introduced a novel surgical technique involving extensive excision of conjunctiva and Tenon's fascia with a limbal-sparing autograft for pterygium surgery.[31] Long-term results demonstrated a low recurrence rate and reduced postoperative complications compared to traditional approaches. This technique, which does not require antimetabolites, may offer a promising alternative for pterygium management.
Yin et al explored the use of interferon alpha-2b eye drops as an adjunctive therapy post-pterugium surgery.[32] They observed a significant reduction in recurrence rates at 12 months in the treatment group compared to controls, suggesting that interferon alpha-2b eye drops may be beneficial for preventing pterygium recurrence in the early postoperative period.
These studies collectively provide valuable insights into optimal surgical techniques and adjuvant therapies for pterygium management. Further research with larger sample sizes and longer follow-up periods is essential to validate these findings and enhance treatment strategies for pterygium excision.
Postoperatively, the eye generally is patched overnight, and it is treated subsequently with topical antibiotics and anti-inflammatory drops and/or ointments.
Theoretically, minimizing exposure to ultraviolet radiation should reduce the risk of development of pterygium in susceptible individuals. Patients are advised to use a hat or a cap with a brim, in addition to ultraviolet-blocking coatings on the lenses of glasses/sunglasses to be used in areas of sun exposure. This precaution is even more important for those patients living in tropical or subtropical areas or for those patients who are engaged in outdoor activities with a high risk of ultraviolet exposure (eg, fishing, skiing, gardening, outdoor construction work).
Postoperatively, after pterygium excision, the topical steroids are slowly tapered. Patients on topical steroids need to be observed to reduce the risk of related problems, such as elevated intraocular pressure and cataracts.[33]
Medical treatment of pterygium consists of over-the-counter (OTC) artificial tears/topical lubricating drops (eg, Refresh Tears, GenTeal drops) and/or bland, nonpreserved ointments (eg, Refresh PM, Hypo Tears), as well as occasional short-term use of topical corticosteroid anti-inflammatory drops (eg, Pred Forte 1%) when symptoms are more intense. In addition, the use of ultraviolet-blocking sunglasses is advisable to reduce the exposure to further ultraviolet radiation.[4]
Clinical Context: Artificial tears provide topical ocular surface lubrication in patients with irregular corneal surfaces and irregular tear films. These conditions are very common in the setting of pterygium.
Clinical Context: A relatively more viscous lubricant for the ocular surface. These thicker preparations tend to blur the vision temporarily; therefore, they are generally used at night, except in patients with severe discomfort.
Clinical Context: A topical corticosteroid suspension used to reduce inflammation in the eye. Use should be limited to eyes with significant inflammation not relieved by topical lubricants.
To reduce inflammation on the ocular surface and other ocular tissues. Corticosteroids can be helpful in the management of inflamed pterygia by reducing the swelling of the inflamed tissues of the ocular surface adjacent to the lesions.