Bifocal eye glasses work by accommodating eyes that are both nearsighted, or myopic, and farsighted, or hyperopic. This means a person requiring both prescriptions is presbyopic. Bifocal vision means a person needs two separate prescriptions, one to see clearly at a distance and a different one to see up close. The person is both nearsighted and farsighted.
bifocal glasses have two different areas.The top area is used for seeing distant and the bottom area is used for viewing near.If you want to see distant objects, then hold your head up and look through the upper part of the lens.If you want to view near, like reading newspaper, then just look through the lower part of your lenses.Hope this helps you.