Vision

The Eye

Our eyes allow us to see the visual image of the environment around us.

The eye works in a similar way to a camera.

Light rays reflected from an object enter the eye and are focused by the lens onto the retina at the back of the eye.

The retina converts the image into electrical signals, which are then sent along the optic nerve to the brain.

There are two main types of light-sensitive cells in the retina:

• Cones — provide colour vision and sharp detail and work best in good light.
• Rods — are sensitive in dim light and are important for night and peripheral vision.

Cones

Cones provide:

• colour vision;
• sharp visual detail; and
• good vision in bright or moderate light.

Cones are spread throughout the retina but are particularly concentrated in the fovea, near the centre of the retina.

The fovea provides our sharpest vision.

When we want to read or inspect fine detail, we move our eyes so that the image falls on the fovea.

Because the fovea contains cones but no rods, a faint object at night may be easier to see by looking slightly to one side of it rather than directly at it.