If you need to read menu, newspapers from a further distance, you have probably developed presbyopia. Bifocal memory metal eyeglasses are the solution to this vision problem. Bifocal flexible memory metal eye glasses are available in soft and RGPs types, disposable type as well as silicone hydrogel extended type up to 30 days.
Multifocal contacts refer to lenses with more than one focal point or power. In this consideration, bifocal contacts are a sub-set of multifocal contacts. Lens design groups multifocal contacts into two categories: alternating vision lenses and simultaneous vision lenses. The latter one still has two types: concentric ring designs and aspheric designs.
With alternating bifocals or translating bifocals, your pupil looks through either the top section or the bottom section of the lenses for different powers in order to get respectively distance vision or close vision. The switching process requires the movement of your eyes, rather than the automatic adjustment of the lenses. Most alternating bifocals are RGPs, and their smaller size performs well during these shifts.
Concentric ring bifocals have a prescription in the center and one or more power rings around. These multiple rings alternate automatically for distance or close vision. The ring number is decided by your pupil size and light condition, while two rings are the most common. Different materials of bifocals bring different rings structures. GP bifocals always feature center-distance while soft bifocals feature center-near. Exceptions of soft bifocals include designs that are center-near on dominant eye but center-distance no non-dominant eye.
Aspheric multifocal contacts function similarly with progressive lenses which have multiple powers. They are the most popular multifocal contacts since they are also concentric and can simultaneously adjust to your vision needs at every moment.
Thanks to technological advancements in bifocals such as monovision and modified monovision, a large number of bifocal contacts are available for your selection. These technologies have helped bifocal contacts gain popularity. In detail, monovision allows your eyes to take a near prescription and distance prescription respectively, both using single lenses. Modified monovision combines single lenses and multifocal lenses on one person.
During bifocal contacts trials from your ECP, two elements are decisive: pupil size and near prescription. Bifocal contacts' fitting is more complex and time-consuming, so you may be charged for the process. Some codes may be obeyed in choosing proper types of multifocal contacts: aspheric contacts fit low near prescription but reject large pupils, and alternating contacts suit high near prescription.
Article Source:http://vision.firmoo.com/contact-lenses/presbyopic-patients-with-varifocal-contact-lenses.html
Multifocal contacts refer to lenses with more than one focal point or power. In this consideration, bifocal contacts are a sub-set of multifocal contacts. Lens design groups multifocal contacts into two categories: alternating vision lenses and simultaneous vision lenses. The latter one still has two types: concentric ring designs and aspheric designs.
With alternating bifocals or translating bifocals, your pupil looks through either the top section or the bottom section of the lenses for different powers in order to get respectively distance vision or close vision. The switching process requires the movement of your eyes, rather than the automatic adjustment of the lenses. Most alternating bifocals are RGPs, and their smaller size performs well during these shifts.
Concentric ring bifocals have a prescription in the center and one or more power rings around. These multiple rings alternate automatically for distance or close vision. The ring number is decided by your pupil size and light condition, while two rings are the most common. Different materials of bifocals bring different rings structures. GP bifocals always feature center-distance while soft bifocals feature center-near. Exceptions of soft bifocals include designs that are center-near on dominant eye but center-distance no non-dominant eye.
Aspheric multifocal contacts function similarly with progressive lenses which have multiple powers. They are the most popular multifocal contacts since they are also concentric and can simultaneously adjust to your vision needs at every moment.
Thanks to technological advancements in bifocals such as monovision and modified monovision, a large number of bifocal contacts are available for your selection. These technologies have helped bifocal contacts gain popularity. In detail, monovision allows your eyes to take a near prescription and distance prescription respectively, both using single lenses. Modified monovision combines single lenses and multifocal lenses on one person.
During bifocal contacts trials from your ECP, two elements are decisive: pupil size and near prescription. Bifocal contacts' fitting is more complex and time-consuming, so you may be charged for the process. Some codes may be obeyed in choosing proper types of multifocal contacts: aspheric contacts fit low near prescription but reject large pupils, and alternating contacts suit high near prescription.
Article Source:http://vision.firmoo.com/contact-lenses/presbyopic-patients-with-varifocal-contact-lenses.html
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