The Pros and Cons of Bifocal Glasses

Bifocal glasses have many aspects and can be quite advantageous and convenient for many. These glasses incorporate lenses meant for both near and far vision.
These can be used by those with eyesight problems, without the need to constantly shift glasses or lenses. Those suffering from both presbyopia and myopia can use these glasses without the need to switch between special reading glasses and glasses for long distance vision, as is the case with single vision glasses. Simply by tilting the eyes to look at that part of the lens, objects far or near can be viewed, they are thus a very useful type of prescription glasses. 

However, one issue with bifocal glasses is the image jump that the viewer experiences as their vision moves across the line between the two types of lenses. This problem persists with bifocal or trifocals but can be alleviated with progressive lenses. These constitute a gradient of power from top to bottom. These glasses give a more natural view with a gradual change from one type of power to another. However some people experience an area of blurred vision on both sides of the lenses. Because of this, some people reject these glasses. On the whole, these glasses have advantages and disadvantages. These need to be carefully weighed in choosing which type of glasses to adopt.

(Source:http://www.glassestribe.com/2013/12/the-pros-and-cons-of-bifocal-glasses.html)