The bifocal glasses is convenient because they eliminate the need to switch back and forth between two pairs of glasses, that is to say, one for distance vision and another for reading. And they only have one pair of prescription lenses instead of two, which can be cost effective. Additionally, they are protective anti-UV coating and anti-glare coating to protect eyes in any light. On the contrary, the bifocal glasses present a main shortcoming that is the image would be jumped when the visual axis passes from the far vision glasses to the reading segment.
The bifocal glasses are the combination of the common eyeglasses, which allow you see near and far things clearly. They have two functions for the users to use which will make it convenient to use, not to change in the limited situation. However, due to the sudden change from far to near vision part, the wearer will feel a little dizzy because of the maladjustment. Nowadays, the progressive eyeglasses are created to make up this disadvantage.