**Question:** All of the following are causes of leukocoria except:

A. Hyphema
B. Keratitis
C. Retinoblastoma
D. Albinism

**Core Concept:** Leukocoria is the medical term for a white appearance of the pupil due to abnormal light reflection. It is a clinical sign that can suggest various pathologies affecting the eye.

**Why the Correct Answer is Right:**
Albinism is a condition characterized by deficiency or absence of melanin pigment in the skin, hair, and eyes, leading to white or excessively pale appearance. While it is related to the eye, it does not cause leukocoria, as it affects the pigmentation but not the light reflection or refraction.

**Why Each Wrong Option is Incorrect:**

A. Hyphema: Hyphema refers to the presence of blood in the anterior chamber of the eye. It causes a red appearance of the eye, not leukocoria.
B. Keratitis: Keratitis is inflammation of the cornea, which is a different part of the eye than the pupil. It does not directly cause leukocoria.
C. Retinoblastoma: Retinoblastoma is a rare eye cancer causing abnormal light reflection due to tumor formation within the eye. Consequently, it is a cause of leukocoria.

**Clinical Pearl:**
It is essential for medical students and healthcare professionals to differentiate between causes of leukocoria (e.g., retinoblastoma) and non-causes (e.g., albinism) to ensure appropriate diagnosis, referral, and management of patients presenting with this clinical sign.

**Correct Answer:** D (Albinism)

**Core Concept:** In albinism, the lack of melanin pigment results in an excessively pale appearance of the eye, but it does not cause leukocoria. Albinism affects the pigmentation but not the light reflection or refraction. This helps to distinguish albinism from causes like retinoblastoma, which directly affect the light reflection resulting in leukocoria.