Contact lenses can be worn most of the day and some may even sleep in them. Although you have the convenience of not needing your glasses to see, a pair of glasses should be available for use. Sometimes, you may not feel like wearing your lenses. But, there are other reasons for having a pair of glasses. For example: if you tear a lens, have allergies that affect your ability to wear lenses, or if you lose a lens. Glasses are also a fashion accessory.