Pterygium in Young Children

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Pterygium is a benign, wedge-shaped, progressive fibrovascular overgrowth of the degenerated bulbar conjunctiva, seen most com­monly on the nasal limbus. The condition is often asymptomatic, especially early in its development. As a pterygium gradually encroaches toward the visual axis, it can cause astigma­tism, which may be the main visual complaint.¹ In addition, the lesion may become inflamed, leading to ocular surface irritation.

Although pterygium is rare in young children, we have treated several of these patients at our medical college.

Epidemiology

Among the general population, the prevalence of pterygium varies widely, with estimates ranging from 0.3% to 29% worldwide. A meta-analysis of pooled data from 20 studies, encom­passing more than 900,000 cases in 12 countries, found an overall prevalence of 10.2%, with a slightly higher rate among men than women.²

Pterygium occurs most frequently among people who live in tropical areas near the equator. Ultraviolet light ex­posure is thought to be the most likely cause, and dust, dryness, and wind are also risk factors.

The peak incidence of primary pterygium lies between the ages of 20 and 40 years; outside of that range, the condition is rarely seen in children and more commonly in persons over the age of 40 years.³ However, the risk fac­tors noted above can particularly affect children who play outdoors.

Pathophysiology

Numerous studies suggest a genetic predisposition to the development of pterygium. During embryological development, there may be cellular migration of keratoblasts prompted by vimentin, a type III intermediate filament protein.

Another theory suggests that increased P53 expression, along with a paucity of tumor suppressor gene, facilitates the abnormal proliferation of limbal epithelium. Type 1 hypersensi­tivity is also known to play a role in the pathogenesis of pterygium.

Histology

Histopathologic examination demon­strates conjunctival mucosa lined by stratified squamous nonkeratinized ep­ithelium with interspersed goblet cells. Compared with adults, children have an increased number of mast cells. The underlying stroma shows fibrocollage­nous tissue, with areas of hyalinization and superficial congested vessels.

Clinical Presentation

The classic presentation of pterygium is a fibrovascular lesion in the palpe­bral fissure, originating in the nasal aspect of the conjunctiva. Typically, the growth progresses gradually and horizontally toward the limbus, cornea, and visual axis. The condition is usually bilateral.

The affected eye may be red, with no discharge. There may be an irritated, gritty sensation, leading to constant eye rubbing.

Refractive effects. A small pterygi­um has few symptoms and no harmful effects. However, as it grows, the child may complain of blurred vision due to development of refractive astigmatism, generally of the with-the-rule type. Frequent headaches may occur as a consequence of the astigmatism.

Differential Diagnosis

Pinguecula. This condition appears as a yellow-white mound or aggregation of smaller mounds on the bulbar conjunc­tiva adjacent to the limbus, remaining localized to the conjunctiva without involving the cornea. The histology is very similar to pterygium, and pinguec­ulae often precede the development of pterygium.

Pseudopterygium. This term de­scribes a band of conjunctiva adhering to an area of compromised cornea at its apex as a result of chemical or thermal burns, trauma, or marginal corneal dis­ease. The lesion is not confined to the palpebral fissure. As an important point of distinction, a probe can be passed beneath a pseudopterygium near the limbus, while this is impossible in true pterygium.

Workup

The clinical diagnosis of pterygium is based on history, anterior segment slit-lamp examination, and refraction to assess for astigmatism.

Staging. Pterygium is graded according to the extent of corneal involvement.

Grade I: at the limbus

Grade II: between the limbus and the pupil

Grade III: extending to the pupillary margin

Grade IV: crossing the pupillary margin

Treatment

Management of pterygium in children is generally the same as in adults. De­finitive resolution may be more difficult to achieve than it is in adults, however, because pterygium recurs more aggres­sively and at a reportedly higher rate of 36.1% in children.⁴

Conservative management. Medical treatment for symptomatic children with small pterygia includes use of artificial tears and weak topical steroids to reduce inflammation and improve comfort.

The child may be advised to wear sunglasses while outdoors; reducing ultraviolet light exposure may decrease the growth stimulus.

Surgery. Surgical therapy may be appropriate for larger pterygia en­croaching on the limbus and progress­ing toward the visual axis.

Indications for surgery include the following:

• Intractable irritation
• Opacity in the visual axis
• Astigmatism leading to visual impair­ment
• Cosmetic concerns

Primary pterygium. In children with a primary pterygium, conjunctival autograft is the treatment of choice.⁵ Conjunctival rotational autograft can be considered, with the caveat that in some active children, constant eye movement may displace the graft.

Recurrent pterygium. In cases of recurrence, a conjunctival autograft technique may be attempted again. As an alternative, we have had good results with the older technique of conven­tional bare sclera pterygium excision. It is important to note that this surgery must be performed with use of adjunc­tive therapies, such as mitomycin C, to reduce the otherwise unacceptable risk of recurrence. However, antifibrotic agents are associated with complica­tions, including corneal melting, cor­neal perforation, prolonged punctate keratopathy, scleral necrosis, secondary glaucoma, and cataract.

Another option is amniotic mem­brane transplantation, but it is costly, requires preservation, and is not widely available.

Postsurgical care. In our clinic, we advise the following postsurgical regi­men: tobramycin sulfate 0.3% drops 6 times per day for 15 days; 1% prednis­olone acetate drops 4 times per day for a week, then tapered over 3 weeks; and 0.5% carboxymethylcellulose sodium drops 6 times a day for a month.

For pain, oral nonsteroidal anti-inflammatory drugs are given in pedi­atric doses according to body weight.

We also instruct the patient not to rub the eye and not to move the eyes excessively.

Follow-up

In our experience, recurrence is more aggressive and occurs earlier—at 4 to 6 months—in children than in adults. Children who have had pterygium exci­sion should be examined every month for 6 months and, subsequently, once every 6 months. Long-term follow-up may yield better understanding of childhood pterygium and its outcome.

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1 Liu L et al. BMJ Open. 2013;3:e003787. doi:10.1136/bmjopen-2013-003787.

2 Noor RA. Malays J Med Sci. 2003;10(2):91-92. www.ncbi.nlm.nih.gov/pmc/articles/PMC3561894/. Accessed Aug. 24, 2017.

3 Monga S et al. Am J Ophthalmol. 2012;154(5):859-864.

4 Ibechukwu BI. East Afr Med J. 1992;69(9):490-493.

5 Yadav AR et al. Indian J Ophthalmol. 2015;63(6):491-495.

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Dr. Dsouza is a senior resident and Dr. Kamath is a professor; both are in the Department of Ophthalmology, Kasturba Medical College, Mangalore, Karnataka, India. Relevant financial disclosures: None.