**Core Concept**
The end organ for vision is responsible for converting light into electrical signals that are transmitted to the brain, allowing us to perceive visual information. This process involves the photoreceptor cells in the retina, which respond to light by initiating a series of chemical reactions.

**Why the Correct Answer is Right**
The correct answer is the retina, specifically the photoreceptor cells (rods and cones) that are embedded in the retina's inner layer. These cells contain light-sensitive pigments (rhodopsin in rods and opsins in cones) that undergo a conformational change when exposed to light, leading to a signaling cascade that ultimately activates the bipolar cells and ganglion cells. The axons of the ganglion cells form the optic nerve, which transmits the visual information to the brain. The retina is a complex neural tissue that is considered a part of the central nervous system.

**Why Each Wrong Option is Incorrect**
**Option A:** The lens is a crucial structure in the eye that focuses light onto the retina, but it is not the end organ for vision. It is a transparent, flexible structure that changes shape to adjust focus.
**Option B:** The optic nerve carries visual information from the eye to the brain, but it is not the end organ for vision. It is a bundle of axons that transmits electrical signals from the retina to the brain.
**Option C:** The cornea is the transparent outer layer of the eye that allows light to enter, but it is not the end organ for vision. It is a stratified epithelium that provides protection and refractive power.

**Clinical Pearl / High-Yield Fact**
The retina is the only part of the central nervous system that is outside the skull, making it vulnerable to damage from conditions such as diabetic retinopathy, hypertensive retinopathy, and retinal detachment.

**Correct Answer:** D.