Ophthalmology · External Eye Disease
The facts most likely to be tested
A pterygium is a triangular, fibrovascular growth that originates from the bulbar conjunctiva and extends onto the cornea.
The primary risk factor for the development of a pterygium is chronic, prolonged exposure to ultraviolet (UV) radiation.
Patients with a pterygium typically present with ocular irritation, foreign body sensation, or cosmetic concerns.
Unlike a pinguecula, a pterygium is characterized by its ability to encroach upon the cornea and potentially induce astigmatism.
The pathophysiology involves elastotic degeneration of the subconjunctival collagen and fibrovascular proliferation.
Surgical excision is indicated only if the lesion causes visual impairment due to corneal astigmatism or visual axis obstruction.
Artificial tears and topical lubricants are the first-line management for symptomatic relief of ocular irritation.
Vignette unlocked
A 45-year-old male construction worker presents to the clinic complaining of a persistent 'growth' on his left eye. He reports occasional redness and a gritty sensation, especially after long days working outdoors. On physical examination, there is a triangular, fleshy, fibrovascular mass extending from the nasal bulbar conjunctiva onto the cornea. Visual acuity is 20/20, and the remainder of the ocular exam is unremarkable.
What is the most likely diagnosis?
Pterygium
The vignette describes the classic presentation of a pterygium, which is a triangular fibrovascular growth encroaching on the cornea, strongly associated with chronic UV exposure.
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High yield triage
Etiology / Epidemiology
Associated with chronic UV light exposure and dry, dusty environments. Common in outdoor workers.
Clinical Manifestations
Triangular, fleshy fibrovascular growth encroaching onto the cornea from the nasal side.
Diagnosis
Slit-lamp examination is the gold standard for diagnosis and assessment of corneal involvement.
Treatment
Observation for mild cases; surgical excision for vision impairment or severe irritation.
Prognosis
High rate of recurrence post-excision; requires long-term UV protection.
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Epidemiology & Etiology
Prevalence is highest in populations living near the equator due to intense UV radiation. Often referred to as surfer's eye, it is strongly linked to prolonged outdoor exposure. Incidence increases with age and cumulative environmental stress.
Pertinent Anatomy
The growth originates in the bulbar conjunctiva and migrates across the limbus. It typically follows a horizontal axis, most commonly in the nasal interpalpebral fissure.
Pathophysiology
Chronic UV-induced damage leads to limbal stem cell dysfunction and fibrovascular proliferation. The lesion is characterized by elastotic degeneration of the subconjunctival collagen. As it advances, it can induce astigmatism by flattening the corneal surface.
Clinical Manifestations
Patients present with a triangular, wedge-shaped growth. Red flags include rapid growth, bleeding, or significant vision loss, which may suggest ocular surface squamous neoplasia. Patients often report foreign body sensation, irritation, and cosmetic concerns.
Diagnosis
Diagnosis is clinical via slit-lamp examination. No laboratory testing is required. If the lesion is atypical or rapidly progressive, biopsy is indicated to rule out malignancy.
Treatment
Mild cases are managed with artificial tears and topical lubricants. For inflammation, short-term topical NSAIDs or mild steroids may be used. Avoid long-term topical steroids due to risk of glaucoma and cataracts. Surgical excision with conjunctival autograft is the definitive treatment for visual obstruction.
Prognosis
Post-operative recurrence is the primary complication, occurring in up to 30-50% of cases without adjunctive therapy. Patients must be counseled on UV-blocking sunglasses to prevent progression and recurrence.
Differential Diagnosis
Pinguecula: yellow, elevated nodule that does NOT cross the limbus
Pseudopterygium: adhesion of conjunctiva to a peripheral corneal ulcer
Ocular surface squamous neoplasia: often has a gelatinous or leukoplakic appearance
Phlyctenulosis: small, white, inflammatory nodules associated with hypersensitivity
Corneal dermoid: congenital, solid, white mass usually present at birth