Not only must prescription eyeglass lenses be precisely cut, they must also fit the face correctly. Otherwise, the effectiveness of the prescription will be compromised. Eyeglasses that slip down the nose will not provide the wearer with the intended lens power and image size. For instance, farsighted individuals who let their eyeglasses slip down their noses will find that the effective power and image size are increased. Nearsighted individuals with slipping eyeglasses will find that the effective power of their lenses is reduced. In each case, the exact amount of change in power will vary with the prescription and the distance the lenses are allowed to slip. Proper fit ensures the effectiveness of one’s lens prescription. Eyeglass frames must fit properly on the bridge of your nose and stay in place whether you are looking up, down, or sideways. Frames are available in many styles, including wire-thin titanium, stainless steel, bold metals, and sleek-colored laminated plastics. The distance between your temples should determine the width of your eyeglass frames, while the temple-to-ear measurement ensures that the eyeglass frames will be placed correctly in front of the face, with lenses properly positioned.