Vision Basics Explained: Eye Parts and Their Functions

The iris is the coloured ring. It surrounds the pupil and helps regulate the amount of light entering the eye.

The retina contains photoreceptor cells that detect light. These cells begin the process of turning light into electrical signals.

The optic nerve transmits visual information to the brain. The brain then interprets these signals as images.

Photoreceptors convert light to nerve signals. These signals are then passed through retinal neurons and sent along the optic nerve.

The cornea and lens focus images on the retina. The cornea does much of the bending, and the lens fine-tunes focus for near and far objects.

The cornea does much of the focusing. The big change from air to cornea causes strong bending of light.

It protects and supports the eye. The sclera is tough and helps the eyeball keep its shape.

The brain processes visual information to create perception. It learns to interpret the retinal image so the world appears upright and stable.

Vitreous humor is the gel-like interior. It helps the eye keep its shape and supports the retina.

A–C are real eye parts; piston is not. Retina detects light, the lens helps focus, and the optic nerve carries signals to the brain.

The cornea is the first major surface light meets. After passing the cornea, light goes through the pupil toward the lens and retina.

No rods or cones at the optic disc. That area cannot detect light because the optic nerve leaves the eye there.

It’s a normal feature caused by the optic nerve exit point. Usually, you don’t notice it because the brain fills in gaps and the other eye overlaps the view.

Rods and cones detect light. Rods are more sensitive in dim light, while cones help with colour and fine detail.

That’s the basic pathway of vision: light enters, is focused, and is detected by the retina. The optic nerve carries signals to the brain, where the image is perceived.

The pupil is the opening that allows light to enter. The iris changes the pupil size to control how much light gets in.

The iris changes the pupil size depending on light levels. In bright light, it makes the pupil smaller, and in dim light, it makes it larger.

The iris constricts the pupil to reduce light entry. This helps protect the retina from too much light.

A larger pupil allows more light in. This is one reason vision improves in dim conditions after a short time.

The lens forms a real, inverted, smaller image. Your brain then interprets the information so you perceive the world upright.