Multifocal Contact Lenses
Multifocal contact lenses
Have you stopped wearing contact lenses because you need bifocals to read up close? If you have continued wearing contact lenses, have you been burdened with having multiple pairs of reading glasses in many locations so that you can read?
Are you wearing one contact lens for far and one for near and wishing there was a better way for you to see at both distances?
Multifocal contact lenses are special contact lenses used to correct distance and near prescriptions at the same time.
What are the advantages of the multifocal contact lenses?
Multifocal contact lenses offer an excellent option for those who need good depth perception as well as those who would like to see at intermediate distances such as computer distance.
Manufacturers have been continually developing new multifocal contact lenses with better materials and designs, available in both soft and
rigid gas permeable materials.
Here are three examples of designs of multifocal contact lenses: Concentric: This design has rings of distance and near focus. There is no intermediate distance correction. The center of the lens can be either near or distance vision, depending on the design. The patient sees both distance and near images at the same time, and the visual system ‘learns’ to select the clearer image. It may take time to adapt to this design.
Aspheric: This design has either a distance or near center and an aspheric progressive area that provides the Rx for intermediate and near or distance prescriptions, seeking to provide the most natural vision. The zones have a gradual change in power similar to a progressive pair of glasses as opposed to the jump in images seen with lined bifocal glasses.
Translating: This is an older design, more frequently used with gas permeable lenses because it is the ability to “translate,” or to move up and down to provide clear distance or near vision correction, that makes them successful. When the patient looks down while reading, the eye moves into the near vision area and sees clearly up close.
Why can’t you read anymore with your contact lenses? Did it seem like it happened all of a sudden?
In the above diagram, the following structures are represented by the numbers:
2. Crystalline Lens
3. Ciliary Body
The zonules are like elastic bands that shorten when you are focusing on a near object making the crystalline lens short and fat. When you focus far away, the zonules stretch out and elongate making the crystalline lens taller and skinnier. After age 40, these zonules become less elastic and less pliable to shorten and focus at near. Sometimes the decrease in elasticity of the zonules is gradual and hard to discern. Other times it seems like it happens all of a sudden!
Are you hurting your eyes by using monovision; i.e., one contact lens for far and one for near?
No. You are not hurting your eyes by using the monovision alternative. You can function comfortably with your dominant eye fitted for far and your non-dominant eye fitted for near.
There are also other viable options like fitting the dominant eye for far and fitting the non-dominant eye with a bifocal contact lens. This is called modified monovision and can help you see three distances: far, intermediate (or computer distance) and near.
The main disadvantage with the monovision modality is the decrease or loss of depth perception, especially noticeable when you need higher reading powers. This loss of depth perception is not acceptable for certain career fields such as pilots.
How do you know which is the best option for you?
What are your lifestyle needs? What are your occupational needs? Do you need good distance vision with excellent depth perception? Monovision is not the best option for you. Do you need to be in front of the computer most of the day? Do you need to read many smaller print documents? You will prefer multifocal contact lenses with better vision at near and with an aspheric periphery to correct your intermediate distance. What is your pupil size? Remember some of these designs have central zones of different sizes and you don’t want your pupil to be too small for that central zone. What is your add power? Some options work better with lower add powers. For example, higher add powers make monovision difficult to tolerate.
Consult your eye practitioner to find out if you are a good candidate for these lenses.
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