**Core Concept**
Sympathetic ophthalmitis is a rare, bilateral granulomatous uveitis that occurs following a penetrating eye injury or surgery, often affecting individuals with a history of ocular trauma or surgery. This condition is characterized by an autoimmune response to ocular antigens, leading to inflammation in both the injured and uninjured eye.

**Why the Correct Answer is Right**
The first sign of sympathetic ophthalmitis is typically a decrease in vision in the uninjured eye, often accompanied by mild to moderate anterior uveitis. This occurs due to the autoimmune response to ocular antigens released from the injured eye, triggering an inflammatory response in the uninjured eye. The breakdown of the blood-ocular barrier in the uninjured eye allows for the entry of immune cells, leading to inflammation and vision loss.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not specified, making it impossible to provide a correct explanation for why it is incorrect.
* **Option B:** While vision loss can occur in sympathetic ophthalmitis, it is not the first sign. The first sign is often a decrease in vision, but this can be followed by other symptoms such as pain, redness, and photophobia.
* **Option C:** This option is not specified, making it impossible to provide a correct explanation for why it is incorrect.

**Clinical Pearl / High-Yield Fact**
Sympathetic ophthalmitis is a rare but serious condition that requires prompt recognition and treatment to prevent permanent vision loss. Ocular trauma or surgery can trigger this condition, highlighting the importance of proper wound management and follow-up care in patients with a history of ocular injury.

**Correct Answer: D**.