**Core Concept**
Measles can cause sudden loss of vision in children due to the development of post-measles blindness, also known as measles keratitis or panuveitis. This condition is a rare but serious complication of measles, leading to inflammation of the iris, choroid, and retina, resulting in vision loss.

**Why the Correct Answer is Right**
The correct answer is related to the development of post-measles blindness, which is a known complication of measles in children. The pathophysiology involves the activation of the immune system in response to the measles virus, leading to inflammation and damage to the uveal tract, including the iris, choroid, and retina. This can result in vision loss due to scarring and atrophy of the affected tissues.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not directly relate to the sudden loss of vision following measles. While measles can cause a range of complications, including respiratory and gastrointestinal issues, sudden vision loss is a specific and rare complication.
**Option B:** This option is incorrect because it does not accurately describe the most common cause of sudden vision loss in children following measles. While uveitis can cause vision loss, it is not the most specific answer related to measles.
**Option C:** This option is incorrect because it is not a direct consequence of measles infection. While measles can increase the risk of secondary infections, sudden vision loss is a specific complication related to the measles virus itself.

**Clinical Pearl / High-Yield Fact**
Measles keratitis or post-measles blindness is a rare but serious complication of measles, particularly in children. It is essential for clinicians to be aware of this potential complication and to monitor patients closely for signs of vision loss following a measles infection.

**Correct Answer: D. Post-measles blindness.**