BASICS
DESCRIPTION
A pterygium is a benign, limbal, epithelial, wing-shaped, degenerative growth, mostly nasally, that migrates onto the cornea from the conjunctiva and may cause visual distortion or loss of vision if it progresses into the visual axis. It is treated by surgical removal when vision is threatened or if it is a cosmetic problem. Recurrence of the pterygium can be an issue after surgical removal (1).
EPIDEMIOLOGY
• More prevalent in outdoor workers exposed to highly reflective surfaces such as water and sand
• Encountered in latitudes less than 30°, due to ultraviolet (UV) light exposure
• Chemical exposure, excessive dust, wind, and ethnicity have been linked to pterygium formation and growth.
• Genetic considerations and the presence of human papillomavirus may be linked in some cases to pterygium formation (2).
Pediatric Considerations
Usually not seen in children and teenagers, due probably to cumulative exposure to UV light
RISK FACTORS
• Presence of pinguecula
• Exposure to UV light commonly in those living within 30° of the equator
• Wind
• Dust
Genetics
May be a factor but not yet delineated
GENERAL PREVENTION
Use of sun block, UV protective glasses, and hat when exposed to excessive and reflective sun
PATHOPHYSIOLOGY
Actinic degeneration of sensitive limbal stem cells probably in genetically predisposed individuals.
COMMONLY ASSOCIATED CONDITIONS
• Pingueculum
• None beyond the corneal surface
DIAGNOSIS
HISTORY
• Redness nasally usually, but occasionally temporally
• Distorted or reduced vision as pterygium grows toward the visual axis
• Slight irritation as pterygium advances onto the cornea
PHYSICAL EXAM
• Early, small whitish elevated nodule at 9 o’clock limbus
• Later, wing-like growth of fibrovascular tissue extends onto the cornea from nasal limbus mostly.
• May reach and cross visual axis in worst cases
• Hemorrhage from leaking capillaries at pterygium head indicates activity
• Iron line (Stocker’s line) at pterygium head indicates inactivity
DIAGNOSTIC TESTS & INTERPRETATION
Diagnostic Procedures/Other
Biopsy not indicated
DIFFERENTIAL DIAGNOSIS
• Pseudopterygium—conjunctival adherence to the cornea due to inflammation or trauma
• Dermoid of the limbus
• Squamous cell carcinoma (rare)
TREATMENT
MEDICATION
• None for prevention or treatment
• Astringents or vasoconstrictors to reduce redness, but limit use
SURGERY/OTHER PROCEDURES
• Surgical removal of pterygium when it threatens vision or becomes a cosmetic problem
• Removal of pterygium from cornea and conjunctiva with dissection of subconjunctival fibrovascular tissue
• Placement of conjunctival autograft (CAG) from the 12 o’clock position of same eye
• Mitomycin C application before placement of cag when appropriate
• Suture cag into position or use tissue adhesives. If conjunctiva must be spared, use amniotic membrane tissue as transplant (3).
• Mitomycin C should be used judiciously (4).
ONGOING CARE
FOLLOW-UP RECOMMENDATIONS
• Topical steroids must be used postoperatively for at least 6 months in tapering dosage to prevent recurrent pterygium (5).
REFERENCES
1. Chang RI, Ching ST. Corneal and conjunctival degenerations. In: Cornea. Krachmer JH, Mannis MJ, Holland EJ, eds. Philadelphia: Elsevier Mosby, 2005:1001–1002.
2. Hsiao C, Lee B, Ngan K, et al. Presence of human papillomavirus pterygium in Taiwan. Cornea 2010;29:123–127.
3. Kucukerdonmez C, Akova YA, Altinors DD. Comparison of conjunctival autograft with amniotic membrane transplantation for pterygium surgery. Cornea 2007;26:407–413.
4. Young AL, Tam PMK, Leung GYS, et al. Prospective study on the safety and efficacy of combined conjunctival rotational autograft with intraoperative 0.02% mitomycin C in primary pterygium excision. Cornea 2009;28:166–169.
5. Kandavel R, Kang JJ, Memarzadeh F, et al. Comparison of pterygium recurrence rates in Hispanic and White patients after primary excision and conjunctival autograft. Cornea 2010;29:141–145.
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