The frame is essential because it holds the glasses together and provides comfort and stability. Frames have two parts with different functions. The glasses are kept firmly on one's ears via the arms of the frame. The face of the frame keeps the lenses aligned with the eyes. There are three different types of frame materials: plastic, nylon, and metal. All of the materials have different positives and negatives. Plastic can usually be found in less expensive sunglasses. Unfortunately, plastic is a lot less durable and cracks more easily than other materials, so it is a good idea to use plastic reinforced with a metal rod in the arms. Nylon is a excellent choice because it is flexible, light and strong. If Nylon is bent, it has the ability to return to its original position. The final material for the frame is metal, which is also an excellent choice because it's strong and lightweight. However, metal will bend and break more easily than nylon.

The hinge is the part of the frame that holds the arms and face of the frame together. The two types of hinge materials are metal and nylon. Both types of hinges are solid. Some hinges that are not as well made will make the glasses feel brittle and will have the tendency to not stay snugly on the wearer's face. For this reason, higher quality hinges should be purchased.

The lens is the most important part of sunglasses. There are several different types of lenses. Lenses can vary in tint, material, and coating. Higher quality lenses are generally preferred because cheap lenses can distort images. A distorted image causes the eyes to strain. Over a long period of time, this can lead to prolonged headaches, nausea, and dizziness.

The types of lens materials are glass, cr-39, polycarbonate plastic, and acrylic plastic. The

Lenses also vary in tint. A darker tint will absorb a significantly higher amount of light than a lighter tint. Different color tints also serve different purposes. An amber or orange tint will reduce blue light which is the chief component of glare. Therefore, these sunglasses are popular in sports that have a high amount of glare (boating, fishing, and skiing). Brown tints are good for driving, and Gray is good for golfing, running, or cycling. Different tints have different abilities to reduce glare. The best suggestion is to take the sunglasses use into consideration when choosing.

Finally, sunglasses have a variety of coatings. UV protective coatings are a must for sunglasses. The sun's harmful UV rays can seriously damage eyes. Some sunglasses may have a dark tint, but do not have special coatings that protect against UV rays. Other coatings can help improve the scratch resistance on sunglasses. Additionally, mirror or flash coated lenses, and anti-reflective coated lenses can greatly reduce the amount of light absorbed and reduce glare or "halo" effects. Once again, the coating choice should depend on the intended use of the sunglasses.

Sunglasses are essential for people in a variety of situations. Casual sunglasses that are to be used when at the pool or beach do not have to be the most expensive sunglasses available. For most people, sturdy sunglasses that protect the eyes from UV rays and look good are more than enough. However, for anyone who is doing a sport that requires maximum visibility in sunny conditions, high-quality sunglasses are a must. Different lenses and frames can produce highly variant results. Anyone looking for sunglasses should understand in what context the sunglasses will be used, and then choose accordingly. An educated decision will usually result in one choosing sunglasses that he or she is very satisfied with.
About the Author

Nathan Sauer enjoys outdoor sports and prefers Oakley sunglasses.