The purpose of polarization is to protect your eyes from different UV rays. Sunglasses which advertise that they are polarized are a dime a dozen. Yet, there are very few brands which truly deliver the required protection.

Bolle polarized sunglasses is one brand that does.

The human eye is composed of three layers:

• "Sclerotic - This tough layer creates the "white" of the eye except in the front where it forms the transparent cornea. The cornea admits light to the interior of the eye and bends the light rays to that they can be brought to a focus.
• Choroid coat - This middle layer is deeply pigmented with melanin. It reduces reflection of stray light within the eye. In dim light (or when danger threatens), the pupil opens wider letting more light into the eye. In bright light the pupil closes down. This not only reduces the amount of light entering the eye but also improves its image-forming ability.
• Retina- The retina is the inner layer of the eye. It contains the light receptors, the rods and cones (and thus serves as the "film" of the eye). The retina also has many interneurons that process the signals arising in the rods and cones before passing them back to the brain." (users .rcn. com)

Comparing our eyes to a camera will help to better understand how our eyes work. Think of the whole eye as the camera and the cornea, which is the eye's main focusing element, the camera lens.

Rays of light enter the eye in widely diverging angles and the cornea is responsible for bending the "waves" of light in order for them to pass to the pupil - the dark, round center in the middle of the iris (the colored part of your eyeball). From the pupil, the light waves are transported to the lens which "helps to focus light to the back of the eye." (Pasadena eye. com)

"The very back of the eye is lined with a layer called the retina which acts very much like the film of the camera. The retina is a membrane containing photoreceptor nerve cells that lines the inside back wall of the eye. The photoreceptor nerve cells of the retina change the light rays into electrical impulses and send them through the optic nerve to the brain where an image is perceived. The center 10% of the retina is called the macula. This is responsible for your sharp vision, your reading vision. The peripheral retina is responsible for the peripheral vision. As with a camera, if the "film" is bad in the eye (i.e. the retina), you will not get a good picture no matter how good the rest of the eye is." (pasadena eye. com)

(Photo courtesy of avlxyz Alpha, Creative Commons.)

Nobody really know how light travels. The most popular version is that light travels in the form of waves - much like the ones in the ocean. The other theory is that light travels in particles.

Visible light is part of the electromagnetic wave spectrum. All colors travel at the same speed but in different frequencies composed of short and longer waves. For example, the waves for the color violet are more "compressed" than the waves for the color red.

"Light, entering the eye forms an image on the retina which covers the inside of the rear part of the eyeball. It is composed of three layers, the first one of which contains about 125 million photoreceptors called the rods and cones, which receive the light signal. The second layer contains bipolar neurons with synapses for connection with the third layer, which has the ganglion cells with dendrites in contact with the optic nerve, which transmits the information to the brain. Rods and cones have essentially the same structure, but different functions - the rods respond to the intensity of light, whereas cones help us to differentiate between colors.

The space between the lens and the retina is filled with another liquid called the vitreous humour. The aqueous humor and the vitreous humour have approximately the same refractive index, about 1.336. The average refractive index of the eye-lens is 1.396. The eye focuses on different objects by changing the radius of curvature of the lens to change the refractive index. The cornea-lens-fluid system is equivalent to a single converging lens whose focal length can be adjusted by the ciliary muscles." (library. thinkquest. com)

(Photo courtesy of empty007, Flickr.)

Lens polarization is the process by which lenses are coated with a special film in order to reduce glare. It has been compared to a venetian blind and how such "controls the amount of light entering through a window." (wisegeek . com)

"Polarized lenses have a laminated surface containing vertical stripes. These stripes only allow vertically-polarized light to enter the wearer's eyes. Glare is eliminated because the horizontally-polarized light waves cannot bypass the polarized filter." (wisegeek . com)

Bolle polarized sunglasses differ from the rest not only because the lenses are made from the best polycarbonate material, but also because whereas most brands are composed of 5 polarization layers, Bolle polarized lenses are composed of 7 layers.

(Photo and text courtesy of Bill McChesney, Flickr.)

Some of the limitations of Bolle sunglasses include "not being able to be used for regular eyewear with clear lenses. Prescription sunglasses can be tinted a very light gray to accommodate the polarized laminate, but most contact lenses cannot. Some drivers discover that polarized lenses can cause distortions in liquid crystal displays (LCDs). Onboard clocks and other instrument displays may be temporarily unreadable." (wisegeek . com)

When it comes to polarized sunglasses, the Bolle brand has several for you to choose from, depending on your particular style. "Some of the more renowned from Bolle polarized sunglasses models are bolle beta polarized sunglasses, bolle swisher polarized sunglasses, bolle anaconda polarized sunglasses, bolle piraja polarized sunglasses, and bolle boa polarized sunglasses." (bolle polarized sunglasses. Com)