**Core Concept**
The question is testing knowledge of the ocular structures responsible for vision. The correct answer will be related to a condition that spares the structures necessary for vision.

**Why the Correct Answer is Right**
The retina is the innermost layer of the eye containing photoreceptor cells (rods and cones) responsible for converting light into electrical signals that are transmitted to the brain, allowing us to perceive images. The optic nerve is responsible for transmitting these electrical signals from the retina to the brain. Damage to the retina or the optic nerve can lead to vision impairment. However, the question states that vision is not impaired, indicating that the condition affects structures outside of these critical pathways.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the condition affects the retina, which is a critical structure for vision.
**Option B:** This option is incorrect because the condition affects the optic nerve, which is also a critical structure for transmitting visual information to the brain.
**Option C:** This option is incorrect because the condition affects the structures necessary for vision, including the retina and the optic nerve.

**Clinical Pearl / High-Yield Fact**
In conditions affecting the retina or optic nerve, vision impairment is often a hallmark symptom. Preservation of vision in such conditions is rare and should prompt further investigation to identify the underlying cause.

**Correct Answer: C.**