Designs of multifocal contact lenses
Modern people in their middle ages are more active than their counterparts living in several decades ago. A large number of people above 40 still participate in biking, jogging, exercising and playing sports regularly. Presbyopia is quite common among this group of people, who usually need multifocal lenses for adequate vision aid. Bifocal, trifocal and progressive eyeglasses have benefited millions of presbyopic patients. But during an active sport, wearing multifocal eyeglasses is inconvenient and sometimes risky. For athletes and sports enthusiasts, multifocal contact lenses can be a good alternative.
Bifocal and progressive contact lenses
A variety of multifocal contact lenses are available now, providing both convenience and best presbyopia solution. Bifocal contact lenses are the most common type, which offers only distance vision and near vision. Others are just like progressive eyeglass lenses, providing a smooth power transition.
Concentric bifocal design and two variations
Bifocal contact lenses are generally more popular than progressive contact lenses. There are mainly three designs of bifocal contact lenses. The first design is the concentric bifocal pattern, which means that different powers are arranged in different circles. Two variations are both feasible. One pattern has near correction in a small circle at the center, surrounded by a much larger circle for distance vision. The other pattern places near vision in the outer ring.
Alternating bifocal design
The second design is called alternating image design or translating design, which is available only in GP materials. This design is similar in power arrangement to bifocal eyeglass lenses. An alternating image multifocal GP contact lens has a top part for distance vision and a bottom zone for near vision, as well a nearly invisible line for proper fitting. The wearer looks through the lens for distance vision and looks down for near vision. The near zone can also be various shapes: half-moon, crescent or annular. Some alternating image multifocal GP lenses have truncated bottom edge for proper fitting. The alternating image design has only two powers and is unable to deal with intermediate vision.
Simultaneous bifocal design
The third design is simultaneous image design, meaning that distance and near vision can be provide simultaneously. Either in soft or GP materials, simultaneous image multifocal contact lenses have both distance and near vision portions in front of the pupil at the same time. This type of multifocal contacts requires adaption of the brain to choose the proper lens area.
Multifocal contact lenses through monovision
Another technology named monovision can be applied to contact lenses for situations that are beyond normal multifocal contacts. With monovision, your dominant eye wears a single-vision lens for distance vision and non-dominant eye has another lens managing near vision. Modified versions of monovision involve fitting a near-biased or distance-biased multifocal lens in one of the eyes, while leaving the other eye with a single-vision lens.
Soft, GP and hybrid multifocal contact lenses
Multifocal contact lenses come in either soft or rigid gas permeable type with a consideration to material differences. Soft multifocal contacts are more comfortable for part-time wear, while GP multifocal contacts are capable of providing sharper vision but require some time of adaption. Hybrid multifocal contact lenses combine the advantages of both soft lenses and GP lenses. This type of contacts contains a GP center and a soft periphery.
Daily wear and extended wear multifocal contacts
For wearing schedule, multifocal contacts are available both in daily wear and extended wear. In terms of replacement schedule, one-day disposable soft multifocal contact lenses offer the ultimate convenience.
Multifocal contacts for astigmatic patients
While GP lenses are always chosen to correct astigmatism, soft multifocal lenses in a toric design have been created to treat this eye problem. A toric soft lens has zones with unequal thicknesses and creates a prism ballast effect for proper fitting. Hybrid multifocal lenses can also be utilized to deal with astigmatism.
Multifocal contact lenses VS multifocal eyeglassses
It is true that multifocal contact lenses usually can not offer the same visual clarity as multifocal or progressive eyeglass lenses do. Successful multifocal contacts can offer acceptable vision for 80% of the wearer’s daily activities. In some cases, multifocal contacts can never provide satisfying vision for certain people. These unfortunate wearers can get a full or partial refund but the fitting fee is usually not refundable.
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