Bifocal lens vs. Multifocal lens: What's the Difference?
Learn how bifocal contact lenses work

Bifocal contact lenses are designed with the purpose of giving good vision to people who have a condition called presbyopia. The primary symptom of presbyopia is the need to hold reading material, like a menu or newspaper, farther from your eyes to see it clearly.
Bifocal contact lenses are available in both soft and rigid gas permeable materials. Some can be worn on a disposable basis. This has the advantage of having the convenience of throwing the lenses out at specified intervals and replacing them with fresh, new lenses. In addition, one bifocal brand is available in a special silicone hydrogel material.
Bifocal contacts lenses have two prescriptions in the same lens. Multifocal contact lenses have a range of powers similar to spectral lens in each lens. The word multifocal is also used as a blanket term for all lenses with more than one power, which includes bifocals.
Translating Bifocal Contact Lenses
Translating bifocals are very similar to bifocal eyeglasses in function. Bifocals have two power segments, with a line of separation between the distance correction on top and the near correction below. Depending on whether you're looking far or near, your pupil looks through either one or the other.
This mechanism works with bifocal eyeglasses because the lenses stay in place as your eye moves. That may happen with contact lenses, too. Bifocals are smaller in diameter than soft lenses, since most translating bifocals are GP lenses, and they ride on your eye above your lower eyelid. Therefore, the lens stays in place when your gaze shifts downward, allowing you to see through the lower, near-correction part of the lens.
Knowing whether Bifocal Lenses Work for You
Until recently, bifocal lenses were not very popular, even though they have been around for many years. Older bifocal designs didn't satisfy customers and led to frustration among wearers and prescribers alike.
Today, however, new technology has produced more successful designs, as well as a greater variety of designs. If one design doesn't work for you, another design might. Your doctor may also try these related techniques: monovision, the first technique, involves using single-vision lenses to put your near prescription on one eye and your distance prescription on the other. Modified monovision, on the other hand, uses a single-vision lens on one eye and a multifocal lens on the other.
Figuring Out Which Bigocal Lenses work for you
Your eye care practitioner will consider two major factors when choosing a bifocal contact lens: the first is your pupil size and the second is your "add," or near prescription.
Although there are no hard and fast rules with what your eye practitioner may choose to recommend, in general, low adds are better suited to an aspheric multifocal. High adds may be better suited for alternating vision, accomplished with a translating bifocal. However, aspheric multifocal lens may not be right for those with larger pupils.