What is entropion?

Question

What is entropion?

Accepted Answer

Inversion of the eyelid. **Explanation:**

**Entropion** is defined as the inward turning (inversion) of the eyelid margin toward the globe. This condition causes the eyelashes and the outer skin of the lid to rub against the cornea and conjunctiva, leading to irritation, corneal abrasions, and potential scarring. It is most commonly seen in the lower eyelid and is frequently associated with aging (involutional entropion), scarring (cicatricial), or muscle spasms (spastic).

**Analysis of Options:**
*   **Option A (Correct):** Entropion specifically refers to the **inversion of the eyelid margin**. The underlying pathophysiology often involves laxity of the medial/lateral palpebral ligaments and overriding of the preseptal orbicularis oculi muscle.
*   **Option B:** Inversion of the eyelashes is termed **Trichiasis**. While entropion *results* in the lashes touching the eye, trichiasis refers to the misdirection of lashes toward the globe with a normally positioned lid margin.
*   **Option C:** Eversion (outward turning) of the eyelid margin is called **Ectropion**. This leads to exposure of the palpebral conjunctiva and epiphora (overflow of tears).
*   **Option D:** Eversion of the eyelashes is not a standard clinical term, though lashes may appear everted in conditions like Distichiasis (an extra row of lashes).

**NEET-PG High-Yield Pearls:**
*   **Involutional Entropion:** The most common type; caused by the overriding of the **orbicularis oculi** over the tarsal plate.
*   **Cicatricial Entropion:** Often follows Trachoma (the leading infectious cause of blindness) due to scarring of the palpebral conjunctiva.
*   **Surgical Management:** Common procedures include the **Jones procedure** (for involutional) or the **Wies procedure** (transverse lid rotating suture).
*   **Complication:** If left untreated, the chronic mechanical trauma can lead to **corneal vascularization and opacification**. [Practice more Ophthalmology questions on OnCourse]

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