This is a simple trick that opticians use to align plastic reading glass frames with a hair dryer. There are many reasons why you would need to straighten eyeglasses. For one, nobody is perfectly symmetrical and this varies from person to person. Thus, one brand new eyeglass frame will fit a little different for each person. Using this technique will assure the perfect fit with very little effort. Also, with time, no matter how careful we are, the frame gradually changes shape. This is due to many factors, such as slight but prolonged stress on certain areas of the frame and storing them in hot or humid environments.