Exposing your eyes to the sun damages the eyelid, cornea, lens and additional eye parts, according to the Mayo Clinic. Sunglasses can protect the eyes from the sun's harmful rays---however, some types of sunglasses provide added benefits in eyewear protection. Two examples of specialized sunglasses are photochromic and polarized sunglasses.
Significance
Polarized lenses refer to a specialized coating applied to the sunglasses that reduces glare, according to the Mayo Clinic. Polarized lenses do not necessarily indicate that the sunglasses offer ultraviolet protection. Photochromic lenses adjust based on the level of light outside and also are designed to reduce glare.
Adjustability
Photochromic lenses are designed to adjust to the light surroundings, according to All About Vision. When a person is exposed to intense sunlight, the glasses darken accordingly. In less light, the glasses will lighten. This makes photochromic lenses advantageous for those who are highly sensitive to light. Polarized sunglasses are not adjustable in the light, however. They remain the same color despite the level of sun exposure.
Glare-Reducing
Glare is when light rays bounce off a flat surface, such as water, according to REI.com. The light waves that produce glare are horizontal. Polarized sunglasses are designed to reduce these light waves. Because glare is associated with eyestrain, polarized glasses can reduce the incidence of eyestrain. While some photochromic lenses can be polarized, they are not polarized as a means of standard practice. For this reason, they may not be as able to reduce glare, according to All About Vision.
Benefits
Polarized sunglasses are beneficial to those who spend time performing activities commonly associated with glare, according to All About Vision. These include boaters, cyclists, golfers and joggers. Because photochromic lenses can be prescription-based, they offer an advantage to those who do not wish to switch between regular glasses and prescription sunglasses. They also are beneficial to sun-sensitive users who may require a darker tint.
Warning
In some instances, polarized sunglasses may not be indicated for use, according to All About Vision. This includes when a person is engaged in downhill skiing. Polarized lenses can prohibit a person from seeing bumps or icy patches that could result in injury. Because some photochromic lenses are not designed to adjust to light behind an automobile windshield, these lenses may not be useful when driving.
