Sunglasses are a great fashion accessory.  But besides providing style, quality sunglasses do much more:

1.      Sunglasses protect your eyes from harmful UV rays. 

Exposure to ultraviolet (UV) radiation from sunlight has been associated with the development of  cataracts and age-related macular degeneration (AMD).  Quality sunglasses protect your eyes by blocking 100 percent of the sun's harmful UV rays.  Sunglasses also protect the delicate skin around the eyes from UV rays that cause wrinkles and premature aging. 

2.      Sunglasses reduce glare. 

All surfaces reflect light.  Surfaces like water, snow, and automobile windshields can cause extremely bright reflections that are distracting and can interfere with vision.  Reflective glare is particularly dangerous when driving, riding a motorcycle, skiing, or boating.

Sunglasses reduce glare for safer, more comfortable vision.  Polarized sunglasses are particularly effective at reducing glare from surface reflections.

3.      Sunglasses protect your eyes from wind, dust and debris. 

Sunglasses are an effective wind barrier.  Wearing sunglasses reduces the rate of evaporation of tears and helps keep your eyes moist and comfortable.  Sunglasses also help keep contact lenses from drying out and prevent windblown particles from getting in your eyes and causing a corneal abrasion.

Close-fitting, "wrap" style sport sunglasses are particularly effective at reducing the potential for dry eyes and eye injuries from windblown particles.

4.      Sunglasses reduce headaches and eyestrain. 

The pupil controls how much light reaches the light-sensitive retina in the back of the eye.  In dim light, the pupil increases in size (dilates) to allow more light in.  In bright light, the pupil constricts to keep too much light from striking the retina. 

In very bright conditions, the pupil cannot constrict small enough to reduce light to a comfortable level. This causes a person to squint.  (Squinting reduces the space between the upper and lower lids to further reduce the amount of light entering the eye.)  Muscle fatigue associated with squinting and constant constriction of the pupil can lead to headaches and eyestrain.

Sunglasses reduce the amount of light reaching the eyes to a more comfortable level, eliminating the need for squinting and severe pupil constriction.  This increases comfort and reduces the risk of headaches and eyestrain.

5.      Sunglasses improve vision. 

Our eyes require a certain range of ambient light for good vision.  Too much light is as bad as too little.  Excessive brightness causes glare, light-induced "bleaching" of the retina, and squinting - all of which can temporarily reduce visual acuity.  On bright sunny days, sunglasses reduce the amount of light that reaches the retina to more optimal levels for clear, comfortable vision.