## **Core Concept**
Spontaneous subconjunctival hemorrhage refers to bleeding underneath the conjunctiva, the thin membrane covering the white part of the eye (sclera), without any apparent cause or trauma. This condition is often related to vascular fragility or rupture of small blood vessels.

## **Why the Correct Answer is Right**
The correct answer, **C. Rupture of small vessels**, is right because spontaneous subconjunctival hemorrhages typically occur due to the rupture of small, fragile vessels under the conjunctiva. This can be caused by various factors such as hypertension, diabetes, or simply the increased fragility of blood vessels with age. The mechanism involves the sudden increase in pressure within these small vessels, leading to their rupture and subsequent bleeding.

## **Why Each Wrong Option is Incorrect**
- **Option A:** **Injury** is incorrect because while trauma can cause subconjunctival hemorrhage, the question specifically asks about spontaneous cases, implying no obvious external cause.
- **Option B:** **Coagulopathy** is incorrect because although coagulopathy can lead to subconjunctival hemorrhage, it is not the most common cause of spontaneous subconjunctival hemorrhage.
- **Option D:** **Infection** is incorrect because infections can cause various ocular complications but are not a primary cause of spontaneous subconjunctival hemorrhage.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that spontaneous subconjunctival hemorrhages are often benign and self-limiting, resolving on their own without the need for specific treatment. However, recurrent episodes may warrant investigation for underlying conditions such as hypertension or diabetes.

## **Correct Answer:** C. Rupture of small vessels.