**Question:** Most common ocular infection in AIDS:

A. Herpes Simplex Virus (HSV) infection
B. Cytomegalovirus (CMV) infection
C. Toxoplasmosis
D. Cryptococcal meningitis

**Core Concept:** AIDS stands for Acquired Immunodeficiency Syndrome, which is a severe form of HIV (Human Immunodeficiency Virus) infection. AIDS primarily affects the immune system, making the individual more susceptible to opportunistic infections and malignancies. Opportunistic infections are caused by pathogens that usually do not cause disease in healthy individuals.

**Why the Correct Answer is Right:** The correct answer is **B. Cytomegalovirus (CMV) infection**. CMV is a herpesvirus that can cause various infections in AIDS patients, including ocular infections. When the immune system is compromised due to AIDS, CMV can cause retinitis, which is an inflammation of the retina, leading to vision loss and other complications.

**Why Each Wrong Option is Incorrect:**

A. **Herpes Simplex Virus (HSV) infection:** HSV can cause ocular infections, but it is less common in AIDS compared to CMV. HSV can cause herpes simplex keratitis, which is a superficial ocular infection.

C. **Toxoplasmosis:** Toxoplasma gondii is a parasite that can cause ocular toxoplasmosis in AIDS patients. However, it is less common than CMV infection.

D. **Cryptococcal meningitis:** Cryptococcal meningitis is a common complication of AIDS involving the central nervous system, but it is not specific to ocular infections.

**Clinical Pearl:** In AIDS patients, it is essential to consider CMV retinitis as the most likely cause of ocular infections. Prompt diagnosis and treatment can prevent severe visual impairment and blindness.