**Core Concept**
Anterior uveitis can lead to complications in the posterior segment of the eye, resulting in decreased vision. This is due to the inflammatory response and subsequent damage to the delicate structures within the eye.

**Why the Correct Answer is Right**
Cystoid macular edema (CME) is a common complication of anterior uveitis, where fluid accumulation in the macula leads to vision loss. The inflammation in the anterior segment of the eye can cause the release of cytokines and other mediators that increase vascular permeability, leading to the accumulation of fluid in the macula. This fluid accumulation disrupts the normal architecture of the macula, leading to vision loss. The macula is responsible for central vision, and damage to this area can result in significant visual impairment.

**Why Each Wrong Option is Incorrect**
**Option A:** Exudative retinal detachment (RD) is a possible complication of posterior uveitis, not anterior uveitis. It occurs due to the accumulation of fluid under the retina, but it is not a direct consequence of anterior uveitis.

**Option C:** Vitreal floaters are a common symptom of posterior vitreous detachment (PVD), but they are not a cause of vision loss due to anterior uveitis.

**Option D:** Inflammatory disc edema can occur in conditions like optic neuritis, but it is not a direct consequence of anterior uveitis.

**Clinical Pearl / High-Yield Fact**
Cystoid macular edema (CME) is a common complication of anterior uveitis and can occur even after the inflammation has resolved. It is essential to monitor patients with a history of anterior uveitis for signs of CME, as early treatment can prevent long-term visual impairment.

**✓ Correct Answer: B. Cystoid macular edema (CME)**