A 52-year-old male farmer from rural Maharashtra presents with a 3-year history of progressive blurring of vision in the right eye. On examination, he has a triangular, fleshy vascularized tissue originating from the nasal conjunctiva and encroaching onto the cornea, crossing the limbus. The tissue is firm on palpation. Visual acuity is 6/9 in the right eye. What is the most likely diagnosis, and which of the following is the primary risk factor for this condition?

Explanation

## Clinical Diagnosis **Key Point:** Pterygium is a benign, vascularized fibrovascular tissue that originates from the conjunctiva and encroaches onto the cornea, typically from the nasal side (interpalpebral zone). ### Characteristic Features of Pterygium | Feature | Pterygium | Pinguecula | |---------|-----------|----------| | **Origin** | Conjunctiva, crosses limbus | Conjunctiva, does NOT cross limbus | | **Appearance** | Triangular, fleshy, vascularized | Yellow-white, degenerative | | **Encroachment** | Onto cornea | Remains on conjunctiva | | **Vision threat** | Yes (if central) | No | | **Consistency** | Firm, mobile | Firm, immobile | ### Pathogenesis & Risk Factors **High-Yield:** The primary risk factor for pterygium is **chronic ultraviolet (UV) radiation exposure**, particularly UVB. This is why pterygium is more common in: - Tropical and subtropical regions (near equator) - Outdoor workers (farmers, fishermen) - Individuals with prolonged sun exposure without eye protection **Clinical Pearl:** The nasal location of pterygium is due to the nasal conjunctiva receiving more direct UV radiation when the eye is in primary gaze, as the nose casts a shadow on the temporal conjunctiva. ### Pathology 1. **Elastotic degeneration** of conjunctival collagen 2. **Neovascularization** from limbal vessels 3. **Fibroblast proliferation** with abnormal growth 4. **Invasion** across the limbus into Bowman's layer and anterior stroma **Mnemonic:** **PTERYGIUM = Progressive Triangular Encroachment Reaching Cornea, Yoked to UV Irradiance, Mostly nasal** ### Clinical Presentation - Asymptomatic or mild foreign body sensation - Cosmetic concern (redness) - Blurred vision if advancing toward pupillary axis - Induced astigmatism (if encroaching on cornea) - Diplopia (rare, if significant corneal distortion) ### Management Indications - **Observation:** If asymptomatic and not threatening visual axis - **Surgical excision:** If vision threatened, cosmetically unacceptable, or causing significant astigmatism - **Adjuvant therapy:** Mitomycin C (0.02%) or β-radiation to reduce recurrence (20–40% without adjuvant, <5% with adjuvant) [cite:Khurana Ophthalmology Ch 8]