Most frames are categorized as either metal or plastic. Metal eyeglass frames usually have nose pads which an optician can adjust to conform to the bridge of your nose for a customized, comfortable fit.
Many of today's new metal frames are made of titanium. Titanium is stronger and lighter than stainless steel and (like titanium) titanium is hypoallergenic.
Plastic frames are making a comeback because of their ability to add color to complement your skin tones and because they can more dramatically change your appearance. One drawback of plastic frames, though, is that they are typically not as durable as many metal frames. Also, plastic frames usually don't have adjustable nose pads. So if you have a flat, large, or very narrow nose, they may not fit as well as a metal frame with adjustable pads.
If you get new eyeglasses and they don't feel comfortable on your face, this problem can usually be solved by returning to your optician for a minor adjustment of the frame. When you pick up your glasses, an optician should always custom adjust your frame to your facial contours. The optician uses special tools to bend the temples, nose pads, frame front, and other parts for optimal comfort and stability. Otherwise, they may slip or cause soreness due to pressure points on your nose or behind your ears. Proper adjustment is especially important if you have a high prescription or you wear multifocal lenses (bifocal and progressive designs).