**Core Concept**
The patient's symptoms of episodic redness, pain, and relief with sleep, combined with an irregular pupil, suggest a condition that affects the intraocular pressure and may be related to the patient's family history of glaucoma.

**Why the Correct Answer is Right**
The patient's symptoms of episodic redness, pain, and relief with sleep are classic for acute angle-closure glaucoma, a condition where the iris suddenly blocks the drainage angle of the eye, causing a rapid increase in intraocular pressure. This is often precipitated by changes in pupil size, such as during sleep. The patient's irregular pupil may indicate an underlying anatomical abnormality, such as a shallow anterior chamber, which increases the risk of angle closure.

**Why Each Wrong Option is Incorrect**
**Option A:** Open-angle glaucoma is a condition where the drainage angle of the eye is gradually blocked over time, leading to a slow increase in intraocular pressure. It does not typically present with acute symptoms or an irregular pupil.

**Option B:** Uveitis is an inflammation of the uvea, the middle layer of the eye. While it can cause redness, pain, and vision changes, it does not typically cause irregular pupils or episodic symptoms related to sleep.

**Option C:** Keratitis is an inflammation of the cornea. While it can cause redness and pain, it does not typically cause irregular pupils or episodic symptoms related to sleep.

**Clinical Pearl / High-Yield Fact**
In patients with a family history of glaucoma, it's essential to perform a comprehensive eye exam, including tonometry and gonioscopy, to assess the drainage angle and detect potential anatomical abnormalities.

**Correct Answer: C. Keratitis is an inflammation of the cornea. While it can cause redness and pain, it does not typically cause irregular pupils or episodic symptoms related to sleep.