Although we may take it for granted, seeing is one of the most complex functions our bodies perform and it requires the cooperation of many small and intricate parts. The human eye functions much like a camera. Both devices gather, focus, and transmit light through a lens to create an image of the surrounding environment. In order to see, we must have light.1
Perception, Color, and Image
The eye’s retina contains millions of tiny light-sensing nerve cells called rods and cones, which are named for their unique shapes.3
- Cones are responsible for perceiving color and detail.
- Rods and responsible for night vision, peripheral or side vision, and detecting motion.
Rods and cones convert the light from our retinas into electrical impulses, which are sent by the optic nerve to the brain, where an image is produced. The central part of the retina, called the macula, is about the size of a pencil eraser. It is this small area that gives us central vision needed for activities like reading, driving, and working on the computer.3,4
Another function of the eye is to produce tears. Tears are actually an important component of maintaining vision, because they nourish and lubricate the surface of the eye as well as wash away debris. A normal tear consists of water, oil and mucus. If there’s a disturbance of the tear film, people will often experience tearing, burning, irritation or blurred vision.4
There are three main parts in the tear system:
- Glands that make the tear fluid, oil and mucus
- Openings that let tears flow out of the eye
- Ducts inside the nose that tears drain through
When functioning properly, the tear system of the eye keeps the eye wet enough to be comfortable without overflowing. Too much tearing could indicate a problem with tear production or drainage. Some people's eyes do not produce sufficient quality or quantity of tears, causing the condition dry eye.