The key to finding the perfect pair of sunglasses is to pick the right features for your situation. Here are some of the most important features, in addition to the type of lens to choose from, to compare when you buy a pair of sunglasses:

• Lens darkness - What you plan to use the sunglasses for determines the darkness of the tint. For outdoor sports such as mountain climbing and snow-skiing, you want a tint that blocks most light. You can buy sunglasses that block up to 97 percent of light. For most purposes, like going to the beach or driving, look for a tint that absorbs or blocks 70 percent to 90 percent of light. Tints that offer less than 60-percent blockage are mainly good for fashion since they offer only mild protection.
• Special coatings or features - Anti-reflective, hydrophobic, oleophobic, mirror and scratch-resistant coatings improve the functionality of the sunglasses but also add cost. Many of the more expensive sunglasses use specific technologies including polarization, tinting and anti-reflective coatings to achieve increased clarity, better protection, higher contrast or to block certain types of light.