**Core Concept**
Angle closure glaucoma is a condition where the drainage channels in the eye (trabecular meshwork) are blocked, leading to increased intraocular pressure (IOP). This is often due to anatomical changes that reduce the depth of the anterior chamber, making it more susceptible to closure. Key anatomical features include a shallow anterior chamber, a short axial length of the eyeball, and a small cornea.

**Why the Correct Answer is Right**
A flat cornea actually increases the depth of the anterior chamber, making it less susceptible to angle closure. The anterior chamber is the space between the cornea and the iris, and a flat cornea would result in a deeper anterior chamber. This is in contrast to a small cornea, which would result in a shallower anterior chamber and increase the risk of angle closure.

**Why Each Wrong Option is Incorrect**
**Option A:** A small cornea would actually increase the risk of angle closure glaucoma by reducing the depth of the anterior chamber.
**Option C:** An anterior chamber shallower than normal would indeed increase the risk of angle closure glaucoma by making it more susceptible to closure.
**Option D:** A short axial length of the eyeball would also increase the risk of angle closure glaucoma by reducing the depth of the anterior chamber.

**Clinical Pearl / High-Yield Fact**
In angle closure glaucoma, the key anatomical features that predispose to the condition are a shallow anterior chamber, a short axial length of the eyeball, and a small cornea. A flat cornea, on the other hand, is actually protective against angle closure glaucoma.

**✓ Correct Answer: B. Flat cornea**