**Core Concept**
Ketamine is a widely used anesthetic agent that has various effects on the body, including the eye. The question is probing the effect of ketamine on intraocular pressure (IOP), a critical parameter in ophthalmology.

**Why the Correct Answer is Right**
Ketamine is known to increase IOP due to its mechanism of action on the ciliary body muscles. The ciliary body muscles are responsible for the production and drainage of aqueous humor, which in turn affects IOP. Ketamine stimulates the sympathetic nervous system, leading to contraction of the ciliary body muscles, which increases the production of aqueous humor and subsequently raises IOP. This effect is particularly concerning in patients with glaucoma.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because ketamine does not have a known effect on IOP. It is not a primary concern when administering ketamine.
**Option B:** This option is incorrect because ketamine does not decrease IOP. While some anesthetics may lower IOP, ketamine is not one of them.
**Option C:** This option is incorrect because ketamine's effect on IOP is not dose-dependent. The increase in IOP is a consistent effect of ketamine, regardless of the dose administered.

**Clinical Pearl / High-Yield Fact**
It is essential to monitor IOP in patients receiving ketamine, especially those with pre-existing glaucoma. This can be done using tonometry, a non-invasive method to measure IOP.

**Correct Answer: C. Increases IOP**