**Core Concept**
Methanol poisoning leads to visual impairment due to its toxic effects on the retina. Specifically, it affects the optic nerve, causing damage to the retinal ganglion cells, which are responsible for transmitting visual signals to the brain.

**Why the Correct Answer is Right**
Methanol is metabolized to formic acid, a potent neurotoxin that disrupts the normal functioning of the retinal ganglion cells. This results in optic neuropathy, characterized by damage to the optic nerve, leading to visual field defects, blurred vision, and eventually, blindness. The retinal ganglion cells are particularly susceptible to formic acid toxicity due to their high energy demands and high metabolic rate.

**Why Each Wrong Option is Incorrect**
**Option A:** This is a distractor, as it is correct. Ignore it.
**Option B:** Nerve fibers are affected in various neurological conditions, but methanol poisoning specifically targets the retinal ganglion cells, not all nerve fibers.
**Option C:** Rods and cones are photoreceptor cells responsible for detecting light and color. While they may be indirectly affected by methanol toxicity, they are not the primary site of damage.
**Option D:** Rods are more sensitive to light and are responsible for peripheral and night vision. While rods may be affected in some cases of methanol poisoning, the primary site of damage is the retinal ganglion cells.

**Clinical Pearl / High-Yield Fact**
Methanol poisoning should be suspected in patients presenting with visual disturbances, such as blurred vision, double vision, or loss of vision, particularly if they have a history of exposure to methanol-containing substances, such as windshield washer fluid or contaminated alcohol.

**✓ Correct Answer: A. Retinal ganglion cells**