Understanding bifocal contact lens types and designs are essential for getting the right multifocal contacts for your specific vision needs. You will know strengths and weaknesses of each type and design. Once you learn the possibilities you’ll know what vision improvement to expect from from a specific type and design.
Based on the way powers distributed on the lens, the soft bifocal contact lens designs can be divided into aspheric or simultaneous, and concentric vision styles.
Multifocal and Bifocal Contact lens Types and Designs
1. Aspheric Contact Lens. In aspheric design, the lens power changes gradually from the center to the edge of the lens. Here both the distance and near correction are within your pupil area. It means that whenever you look at an object you will see two images, one clear and the other blurred.
If you wear simultaneous contact lenses your eyes will locate and adjust the proper power for the correct distance. And your brain will then learn to see the clear image and ignore the blurred one.
2. Concentric. In concentric vision contact lenses the design places both distance and near correction in several concentric rings. Each of the concentric ring’s circles provides different vision correction. In this design, the distance power is located in the center and the near power is on the periphery part of the lens, or vice versa. An extra ring for intermediate prescription may be added between the other two.
In a certain designs the intermediate and distance prescriptions are blended for a smooth transition from one to the next. These contact lenses work like progressive eyeglass lenses because the powers are finely distributed to different parts of the lens.
If you’re at an early stage of presbyopia, which means your near prescription is not too strong, this design might work well for you. But it isn’t suitable for you if you have large pupil diameters.
Choosing a Multifocal or Bifocal Contact Lens Type and Design
The suitability of a certain design of bifocal lenses to your vision needs depend on the following factors: age, type of work, lighting conditions, shape of eye and size of pupil or other anatomical issues. In this selection process the role of your eye doctor is vital.
An experienced eye doctor usually communicates about what to expect from multifocal lenses and adjust the factors to find the best fitting for specific vision correction needs. Sometimes one eye “fits” into one particular design or material, but the other eye may need a different design. He or she might say that the fitting is good, if you can perform about 80 percent of your main activities.
For example, your occupation requires you to see objects between reading distance and far distance. They are considered a good fit if you can read phone book and, at the same time, working on the computer comfortably.
Overall, multifocal lenses will not solve all of your vision needs. There might be fitting difficulties, longer adjustment period or even visual clarity issues. Your main goal should be getting contacts that are good for your main activity. Other than that, you have to accept compromise. If you’re looking for a perfect fit you may end up becoming a never satisfied patient.