The Eye

The human eye is an extremely complex organ. It has an immense network of nerves, a flexible lens, and specialized cells that sense colors. Small muscles inside the eye move the parts that help to regulate light and keep the world in focus.

Hover over parts of the eye to identify and learn something about them.

The Iris

To see, light must reach special cells inside the eye that send impulses to the brain. Light enters the eye through the pupil, an opening in the middle of the iris. The iris serves a very important function. By controlling the size of the pupil, the iris regulates the amount of light it lets into the eye. Too much light is harmful to your eyes, and too little makes it difficult to see.

This slider controls the iris in the image above:

If you slide it to the right, the pupil dilates. More light will get into the eye and the image on the left side will get brighter.

This slider controls the light level in the environment:

Move the slider to the left to decrease the light, and the iris will automatically adjust.

The Lens

When light reaches your eye from the world around you, it’s at all angles in a jumbled mess. The light must be focused so you can identify shapes and objects. Even before it passes the pupil, the cornea focuses the rays of light. The light is then directed to the lens where it is further refracted to aim it at the focal point near the back of the eye. The lens changes shape to allow you to clearly see objects at varying distances.

Use this slider to bend the eye’s lens in the image above:

When you change the shape of the lens, it changes which rays converge and which diverge. Drag the slider all the way to one side. Then slowly move it in the opposite direction and watch the object in focus shift as the lens changes.

The Retina

The lens focuses light onto the retina, the part of the eye that contains special light-sensitive cells. When these cells, called photoreceptors, are hit by light, they generate electrical signals that are transmitted to the brain via the optic nerve. There are two types of photoreceptors: rods and cones. The rods provide you with peripheral vision, the area at the edges of your visual field. They also give low light vision when it is too dim for clear, colorful images. The cones perceive finer detail and more rapid changes in images than rods. They also allow you to see color. Damaged or mutated cones cause color blindness.

These buttons enable and disable certain photoreceptors in the image above:

Click on the Red Cones button so that Red Cones are off. This will disable the cones that are sensitive to the wavelength of light that corresponds to red. The result simulates a type of color blindness called Protanopia (and is visible in the image on the left). Try the other buttons to see how vision is affected.


Created for the 2018 Explorable Explanations Game Jam.

Ala’ - Art Direction, Concept
Andrew - Research
Jason - Text, Research
Peter - Coding, Design
Tanya - Project Management, Documentation, Research