bifocal prescription glasses

How do Bifocal Glasses Work

Been thinking to yourself "how do bifocal glasses work"? You aren't alone! Bifocal eyeglasses sound a lot more complicated than they are. Like we touched on above, a bifocal prescription allows wearers to get the benefits of two pairs of glasses in one lens. The distance vision prescription, which allows the wearer to see well while looking straight ahead, typically takes up more space than the reading portion of the lens and is situated at the top. The reading portion of the lens sits below the distance prescription with the separation between prescriptions indicated by a thin line that is also called the segment. If you struggle with intermediate vision as well, diagnosed with presbyopia, or wish to hide the visible magnification segment then you should buy progressive lenses.

Types of Bifocal Lenses

This is where things get a little complicated, but we'll break it down for you so that you can move forward with buying in confidence. Make sure when you're getting your lens prescription, your eye doctor should fill you in on what type of lens you need for your bifocal prescription glasses.

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Flat-Top Bifocal Lenses
On this type of lens, the segment designated to close up tasks such as reading is shaped like a capital letter D but flipped sideways. This portion sits in the middle of the bottom half of the lens, with the surrounding portion and top half of the lens designated to the distance prescription. This is the most popular type of bifocal.

Round Segment Bifocal Lenses
These are similar to flat-top bifocals, but the reading portion of the lens is instead shaped like a half-circle. The advantage to round segment bifocals is that the line separating the two lens portions tends to be less noticeable.

Ribbon Segment Bifocal Lenses
This type of bifocal has a more narrow reading segment that is shaped like a rectangle. This allows for some distance viewing capabilities toward the bottom of the lens in addition to the top portion.

Executive Bifocal Lenses
Executive bifocals are based on the original concept developed by Benjamin Franklin. The lens on this type of bifocal is split evenly between the distance prescription and the reading prescription, with the distance segment on top. While the larger reading area might seem ideal, the line between segments is much more noticeable.