One of the prominent sign that you are developing a presbyopia is when you have to hold the newspapers, menus, and other reading materials a bit farther than usual distance in order for you to see it properly and clearly.
These bifocal contact lenses can be manufactured in both rigid gas permeable (GP) materials and soft materials. Some bifocal contact lenses can be worn on a disposable basis which means that you have the freedom to choose to have the convenience of throwing the lenses away at certain intervals (and in some cases, even daily) and replacing those contact lenses with fresh and new ones.
Some bifocal contact lenses can be manufactured as soft multifocal contact lens made of silicone hydrogel material. This type of lens is FDA approved and can be worn up to 30 days of continuous wear. These bifocal contacts lenses have 2 prescriptions in the same lens. They are Alternating Bifocal Contact Lenses and Concentric Ring Designs.
The Alternating bifocal (or translating bifocal) functions much like bifocal eyeglasses because they have two power segments with a line of separation between the distance corrections on top and near below. With bifocal eyeglasses, this type of mechanism is effective because the said lenses stay in its proper place even as you move your eyes, which can happen with contact lenses, too. Given that most alternating or translating bifocals are rigid permeable (GP) lenses, they are usually smaller in diameter than the soft lenses and these lenses are positioned on your eye above your lower eyelid. As a result, when your eyes shifts downward, the lens stays in its proper place letting you to see through the lower near correction part of the said lens.
The Concentric Ring Designs type of bifocal contact lens is characterized by a prescription in the center and one or more rings surrounding it. In general at least two rings are within our pupil area but this may vary as our pupil expands and contracts due to varying light.