**Core Concept**
In glaucoma, coloured haloes around lights are a characteristic symptom, often associated with corneal edema. This phenomenon is due to the scattering of light by the corneal stroma, which is more pronounced when the cornea is edematous.

**Why the Correct Answer is Right**
In angle-closure glaucoma, the cornea is often edematous due to increased intraocular pressure (IOP). As a result, light is scattered by the corneal stroma, causing coloured haloes to appear around lights. However, in open-angle glaucoma, the IOP is typically not high enough to cause significant corneal edema, and therefore coloured haloes are not seen.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because angle-closure glaucoma is indeed associated with coloured haloes, which are a hallmark symptom of this condition.
**Option B:** This option is incorrect because acute angle-closure glaucoma, not open-angle glaucoma, is the type of glaucoma where coloured haloes are typically seen.
**Option D:** This option is incorrect because normal-tension glaucoma (NTG) is a subtype of open-angle glaucoma, where the IOP is within normal limits, but optic nerve damage still occurs. However, coloured haloes are not typically seen in NTG.

**Clinical Pearl / High-Yield Fact**
In glaucoma, coloured haloes are often a sign of angle-closure glaucoma, which requires prompt treatment to prevent vision loss. Remember that coloured haloes are a red flag symptom that warrants further investigation.

**Correct Answer:** B. Open-angle glaucoma