**Core Concept**
Hypermature sclerotic cataract is a type of cataract characterized by the complete liquefaction of the lens cortex, leading to a hard, white, and dense nucleus surrounded by a clear fluid. This condition is often seen in elderly patients and can cause complications due to the altered lens architecture.

**Why the Correct Answer is Right**
The most common complication of hypermature sclerotic cataract is posterior capsule rupture and vitreous loss during cataract surgery. This is because the hard nucleus is prone to cracking and disintegration during surgery, releasing the liquefied cortex into the anterior chamber and potentially leading to posterior capsule rupture. The altered lens architecture and the presence of liquefied cortex make the surgery more challenging.

**Why Each Wrong Option is Incorrect**
* **Option A:** Cataract-related glaucoma is not a direct complication of hypermature sclerotic cataract.
* **Option B:** Uveitis is not typically associated with hypermature sclerotic cataract.
* **Option C:** Posterior subcapsular cataract is a different type of cataract and not a complication of hypermature sclerotic cataract.

**Clinical Pearl / High-Yield Fact**
When performing cataract surgery on a hypermature sclerotic cataract, it is essential to carefully manage the nucleus and cortex to prevent posterior capsule rupture and vitreous loss. This can be achieved by using a gentle technique and maintaining a clear visual axis throughout the surgery.

**Correct Answer: C. Posterior capsule rupture and vitreous loss.**