If you require multiple prescription glasses for different uses, such as one pair for reading and another for watching TV or driving, then you should look into getting Varifocal Glasses. These glasses combine multiple prescription strengths into one set of lenses, so that you don't need to have more than one pair of glasses. Varifocal Glasses have lenses that change in strength - they gradually change from top to bottom, so depending on where you look in the lenses, you'll see differently. When you look straight ahead while wearing these glasses, you use the portion of the lenses that allows you to see clearly at a distance. When you want to look at something closer, such as a book, you lower your gaze and use the close up portion of the lenses. Varifocal Glasses are similar to bifocal glasses, but are different in how the lenses are constructed. With bifocal lenses, there is a visible dividing line between the two halves that separates the close up portion from the distance portion. With varifocal lenses, there is no line - instead, the change between powers is gradual, so there is no need for two pieces of lens to be joined together, as there is with bifocals. However, for some people, bifocals may be a better option, as the close up portion is easier to locate than with varifocals, and the edge distortion that varifocals have can be bothersome to some people. In the past, Varifocal Glasses have tended to require very large frames, because of the nature of the lenses. However, recent technology has allowed the lenses to be used in smaller frames as well, so you will not need to have large, deep glasses. These specialist lenses can also take some getting used to, as you need to learn where each area starts and ends, and train yourself to switch to looking through those areas automatically. Once you get used to them, however, the success rate for these glasses is very high, and most who try them prefer them to multiple pairs of single vision glasses.