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# Pterygium

A wing-shaped, fleshy growth of the white of the eye that creeps onto the [cornea](https://durgical.com/en/anatomy/cornea/), linked to sun, wind and dust; common in sunny countries like Colombia.

Updated 2026-11-01

## Structures involved

Tap one to see what it is and open it in 3D.

- [Cornea](https://durgical.com/en/anatomy/cornea/)
- [Sclera](https://durgical.com/en/anatomy/sclera/)
- [Iris](https://durgical.com/en/anatomy/iris/)
- [Eyelids](https://durgical.com/en/anatomy/superior-tarsus/)
- [Lacrimal gland](https://durgical.com/en/anatomy/lacrimal-gland/)

## Why it happens

- [The eye wall: cornea, sclera, uvea and lens](https://durgical.com/en/histology/the-eye-wall-cornea-sclera-uvea-and-lens/)

## What it is

A benign, triangular fibrovascular growth of the bulbar conjunctiva that extends onto the cornea, almost always on the nasal side of the eye. It is a degenerative change caused mainly by chronic ultraviolet exposure. Small pterygia cause irritation and cosmetic concern; large ones can distort the cornea or cover the visual [axis](https://durgical.com/en/anatomy/axis/).

## Who gets it

Prevalence rises toward the equator in the so-called pterygium belt. Colombia and the rest of tropical Latin America have high rates, particularly among outdoor workers (farmers, fishers, construction and street vendors) and people living at high altitude, where UV is intense. It is more frequent in men and after age 30.

## Causes

- Chronic ultraviolet radiation, the main factor
- Chronic irritation by wind, dust, sand and smoke
- Dry eye and chronic ocular surface inflammation
- Genetic susceptibility in some families

## Risk factors

- Outdoor work or life near the equator or at high altitude
- Not wearing sunglasses or hats
- Male sex and age over 30
- Dry, dusty or windy environments
- Previous pterygium surgery (recurrence)

## Pathophysiology

UV light, focused onto the nasal limbus by the shape of the eye and nose, damages limbal stem cells and conjunctival fibroblasts. The barrier between conjunctiva and cornea weakens, and altered fibroblasts with growth factors and new vessels produce a fibrovascular sheet that invades the corneal surface and Bowman's layer. Traction on the cornea flattens it along one axis and causes astigmatism; the advancing head can eventually block the pupil.

## Classification

- Primary or recurrent
- By corneal extent: limited to the limbus, extending onto the cornea, or reaching or crossing the pupillary area
- By activity: atrophic (thin, visible vessels underneath) or fleshy and vascular (more likely to grow and recur)

## Symptoms and signs

- A visible, pinkish triangular tissue growing from the nasal conjunctiva onto the cornea
- Foreign-body sensation, burning, redness and tearing, especially when inflamed
- Blurred vision from induced astigmatism
- Loss of vision if it covers the pupil
- Restricted eye movement or double vision with large or recurrent lesions

## Red flags

- Rapid growth, a gelatinous or leukoplakic surface, feeder vessels or an atypical (temporal) site: rule out ocular surface squamous neoplasia
- Lesion approaching the visual axis
- Progressive drop in vision or increasing astigmatism
- Double vision after previous surgery (scarring)

## Diagnosis

**Clinical**
Clinical diagnosis by slit-lamp examination: the growth is measured from the limbus and graded by thickness and vascularity, and visual acuity is recorded.

**Tests**
Corneal topography to quantify astigmatism before surgery. Histology of the excised tissue when the appearance is atypical.

**Imaging**
Photographic documentation to follow growth over time; no other imaging is needed.

## Differential diagnosis

- Pinguecula (yellowish, raised conjunctival lesion that does not cross onto the cornea)
- Ocular surface squamous neoplasia
- Pseudopterygium after a chemical burn, trauma or ulcer (not anchored firmly, a probe passes beneath it)
- Conjunctival naevus or other conjunctival tumour
- Episcleritis with nodular inflammation

## Goal of treatment

Relieve irritation, slow growth through UV protection, and remove the lesion before it affects vision, with a technique that minimises recurrence.

## Treatment

**Lifestyle**
UV protection with wraparound sunglasses and a wide-brimmed hat, and avoiding dust and wind.

**Conservative**
Lubricant eye drops for irritation and dryness.

**Medical**
Short courses of anti-inflammatory eye drops for inflamed episodes, under ophthalmology supervision.

**Surgical**
Excision when vision is threatened, astigmatism increases, motility is restricted or symptoms persist; the bare area is covered with a conjunctival autograft fixed with tissue glue or sutures, which greatly lowers recurrence.

**Medical**
Antifibrotic agents applied during surgery or amniotic membrane grafts in recurrent cases.

## Complications

- Irregular astigmatism and reduced vision
- Obstruction of the visual axis
- Recurrence after simple excision, often more aggressive
- Restriction of eye movement and diplopia
- Scleral thinning after the use of antifibrotic agents

## Prognosis

Benign. Many stay small for years. With autograft surgery recurrence is low; simple bare- [sclera](https://durgical.com/en/anatomy/sclera/) excision recurs frequently.

## Prevention

- Sunglasses that block UV and hats from childhood, particularly in outdoor workers
- Eye protection against dust and wind
- Treating dry eye

## Test yourself

Think of the answer, then tap the question to see it.

## Main environmental risk factor for pterygium?

Chronic ultraviolet light exposure.

## How is a pterygium distinguished from a pinguecula?

A pterygium grows onto the cornea; a pinguecula stays on the conjunctiva.

## On which side of the eye is a pterygium usually found?

The nasal side.

## Which surgical technique lowers recurrence after excision?

Covering the defect with a conjunctival autograft.

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## Related conditions

- [Dry eye disease](https://durgical.com/en/conditions/dry-eye-disease/)
- [Conjunctivitis](https://durgical.com/en/conditions/conjunctivitis/)
- [Keratitis and corneal ulcer](https://durgical.com/en/conditions/keratitis-and-corneal-ulcer/)
- [Cataract](https://durgical.com/en/conditions/cataract/)
- [Actinic keratosis](https://durgical.com/en/conditions/actinic-keratosis/)
- [Cutaneous squamous cell carcinoma](https://durgical.com/en/conditions/cutaneous-squamous-cell-carcinoma/)
- [Basal cell carcinoma](https://durgical.com/en/conditions/basal-cell-carcinoma/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Pterygium](https://medlineplus.gov/ency/article/001011.htm) (MedlinePlus, US National Library of Medicine, 2026).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/conditions/pterygium/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/pterygium/