**Core Concept**
Sympathetic ophthalmitis is a rare, bilateral granulomatous uveitis that occurs after penetrating eye injury, typically involving the ciliary body or choroid. This condition is characterized by an autoimmune response, where the body's immune system mistakenly attacks the uninjured eye after an initial insult to the other eye.

**Why the Correct Answer is Right**
A penetrating injury to the ciliary body or choroid can lead to the release of ocular antigens, which triggers an autoimmune response. This response is mediated by T-cells, which recognize the ocular antigens as foreign and initiate an immune response against the uninjured eye. The ciliary body is particularly susceptible to this type of injury, as it contains a high concentration of immune cells and is rich in blood supply, facilitating the spread of antigens and the immune response.

**Why Each Wrong Option is Incorrect**
**Option A:** Glaucoma is a group of eye conditions that damage the optic nerve, often due to increased intraocular pressure. While glaucoma can lead to vision loss, it is not a direct cause of sympathetic ophthalmitis.

**Option B:** Trachoma is a bacterial infection of the eye caused by Chlamydia trachomatis, leading to chronic conjunctivitis and potentially causing blindness in severe cases. However, trachoma is not associated with sympathetic ophthalmitis.

**Option D:** Uveitis refers to inflammation of the uvea, the middle layer of the eye. While uveitis can be caused by various factors, including infections and autoimmune disorders, it is not a direct cause of sympathetic ophthalmitis.

**Clinical Pearl / High-Yield Fact**
It is essential to note that sympathetic ophthalmitis can occur even years after the initial injury, making it crucial for patients with a history of penetrating eye injury to be followed closely for signs of uveitis.

**✓ Correct Answer: C. Penetrating injury to Ciliary body**