TYPES OF CORRECTIVE LENS
Single vision lensesCalled single vision, these lenses feature one correction for a given distance: myopia, hypermetropia and/or astigmatism. They are known as single vision because the optical power is the same for the entire lens.
Progressive or varifocal lensesProgressive lenses do not have any visible lines so they are more aesthetically appealing.
The power gradually changes from the top to the bottom of the lens. It is a more functional lens because the person wearing this type of lens has “continuous” vision.
It makes it possible to focus on objects at variable distances whereas a bifocal lens only allows clear vision at two given distances.
Free Form Digital lensesAvailable on a wide range of lenses, Digital Free Form technology guarantees the highest level of visual performance with outstanding style. It results from an improved inner part of the lens with a significantly larger field of vision.
This has been achieved by bringing the optical surface of the eye closer, with progression and cylinder correction on the inner surface of the lens. This manufacturing process is a result of a reduction in peripheral distortion and an improvement in the field of vision compared with standard progressive lenses.
The result is a Digital Free Form lens based on the individual requirements of the user without the need for additional eye tests or specific opticians' instruments. Thanks to the new Digital Free Form technology, 98% of users who have taken part in acceptance testing have adopted these lenses very quickly.
Degressive or Occupational/Workplace lensesThe purpose of degressive or occupational/workplace lenses is first to correct near vision, then intermediate vision with decreasing power towards the top of the lens.
Four fixed degressions are possible from 0.75, 1.25, 1.75 or 2.25 dioptre depending on the needs.
The lens's lower correction allows the wearer to read (at 35 cm for example) like a progressive lens.
The degression power makes it possible to see clearly at an intermediate distance, on a screen for example. The more the wearer looks up, the clearer the distance view will be.
Except for special cases, this lens does not correct distance vision and is therefore not suitable for driving.
Bifocal lensesBifocal lenses are designed for people who require two prescriptions, one for distance and for near vision.
The upper part of the lens corrects distance vision and the lower area corrects near vision.
PolycarbonateThis lens is by far the most resistant of all.
Polycarbonate is 10% thinner than glass and 15% thinner than plastic.
But it is a soft plastic and is therefore easily scratched so an anti-scratch coating is applied as standard.
This material is particularly recommended for protection in the workplace.
Polycarbonate provides the added advantage of absorbing all ultraviolet rays up to 380 nm (99.99%).
CR39This is a plastic resin. Its advantages are robustness, 50% lighter, organic lenses are less likely to fog up and they absorb some ultra-violet rays.
On the other hand, they scratch easily and to prevent this an anti-scratch coating is required.
At equal power, they are thicker than mineral or polycarbonate lenses.
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