**Core Concept**
The patient's symptoms are indicative of a condition that affects the eye, specifically related to the intraocular pressure (IOP) regulation. The symptoms of coloured halos around lights, nausea, and vomiting suggest a condition that is causing optic nerve damage due to increased pressure within the eye.

**Why the Correct Answer is Right**
The patient's symptoms are most likely due to Acute Angle Closure Glaucoma (AACG). AACG occurs when the iris suddenly blocks the drainage angle of the eye, causing a rapid increase in IOP. This increased pressure damages the optic nerve, leading to symptoms such as coloured halos around lights, nausea, and vomiting. The normal IOP reading is misleading, as AACG can present with normal IOP in the early stages.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because while High Myopia can cause eye strain and blurred vision, it is not typically associated with the symptoms described.

**Option B:** This option is incorrect because while Dry Eye Syndrome can cause eye discomfort and blurred vision, it is not typically associated with the symptoms described, particularly the coloured halos around lights.

**Option C:** This option is incorrect because while Migraine can cause nausea and vomiting, it is not typically associated with the coloured halos around lights and is not a direct cause of optic nerve damage.

**Clinical Pearl / High-Yield Fact**
In AACG, the symptoms can be sudden in onset and may be accompanied by severe eye pain, blurred vision, and even loss of vision if not promptly treated. Remember the mnemonic "COAST" for AACG: Coloured halos, Optic nerve damage, Acute onset, Severe symptoms, and Treatment urgency.

**Correct Answer: C. Acute Angle Closure Glaucoma.