## **Core Concept**
Angular conjunctivitis, also known as angular blepharoconjunctivitis, is an infection of the conjunctiva and the corners of the eyelids. It is commonly caused by specific types of bacteria. The condition is characterized by inflammation and redness, particularly at the angles of the eyes.

## **Why the Correct Answer is Right**
The correct answer, *Moraxella lacunata*, is a type of Gram-negative coccobacillus that is commonly found in the environment and on the skin. It is known to cause infections in the eyes, particularly angular conjunctivitis. This bacterium infects the conjunctiva and the meibomian glands at the corners of the eyelids, leading to the characteristic symptoms of the condition.

## **Why Each Wrong Option is Incorrect**
* **Option A:** *Staphylococcus aureus* can cause various types of eye infections, including blepharitis and conjunctivitis, but it is not the most commonly associated organism with angular conjunctivitis.
* **Option B:** *Haemophilus influenzae* can cause conjunctivitis, especially in children, but it is not specifically linked to angular conjunctivitis.
* **Option D:** *Streptococcus pneumoniae* is known to cause various infections, including conjunctivitis, but it is not the primary cause of angular conjunctivitis.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that angular conjunctivitis is often associated with *Moraxella lacunata* and can be treated with antibiotics. A classic clinical clue is the presence of inflammation and discharge localized to the corners of the eyes.

## **Correct Answer:** . Moraxella lacunata