Sunglasses were once a simple thing to buy. You only had to stop by the drugstore, choose a frame that you liked and walk out the door with it shielding your eyes. The lenses were almost always a simple dark brown, the frames either plastic or wire. But nowadays, when you walk down a busy street in the afternoon, you see sunglasses that are green, grey, purple and red, metallic and plastic, reflective or not. Buying a good pair of sunglasses has become more complicated; which one is the right choice? You need sunglasses made of different materials, for different purposes.

When it comes to lenses, a person can wish to change the colors around for fashion or health reasons. Brown, green and grey are considered the "standard" colors, mostly because they cause the least distortion to how you see colors. Blue and purple are for fashion purposes and have no medical use. Red, however, is good for lower light conditions because they enhance contrast. They do come with the side effect of color distortion, as do orange and yellow. The latter is used by golfers for its depth perception properties as well as color enhancement. In addition to the color of the lenses, special effects such as mirroring and polarization can be applied depending on the purpose of the sunglasses.

Polaroid lenses reduce the glare, and mirror lenses reflect some of the light, making it ideal for high light conditions. The lenses themselves can be made from either glass or plastic.

While the lens may the part more relative to the eye, some attention must be given to the frame itself as well. Plastic remains the most common choice and has no particular benefits or uncomfortable side effects. Metal frames are also very popular and have the same strength as plastic. Sometimes they come with small springs to increase flexibility and make them a little more comfortable and secure. The most flexible material is nylon and it is commonly used in sports due to its flexibility and light weight.

The way the frame holds the lens is also a choice you can make. Full-frame sunglasses are sturdier and more secure, but there is no doubt that frameless glasses are currently more fashionable. Some find the lighter weight uncomfortable and prefer to go with half frame glasses, a good mix of comfort and sturdiness. If you find yourself at a loss, consult with your optometrist or the person in charge of sales in your sunglasses store. In the end, the only thing that matters is getting a pair that suits your exact needs.