Els lents bifocals contenen dues prescripcions diferents a la mateixa lent. El propòsit principal dels bifocals és proporcionar l'equilibri òptim entre la visió a distà ncia i les necessitats de visió centrant-se d'aprop. Aquests lents estan disponibles amb els segments de lectura en una varietat de formes i amples, incloent opcions d'ulleres de sol. La forma dels bifocals llegir més popular és el Flat-Top (també coneguda com a recta superior o segment D), que és d'uns 28 mm d'ample. WLC ofereix una sèrie d'opcions per a l'usuari de lents bifocals.
How to view through a bifocal lens
SHAPES OF BIFOCAL LENSES
AVAILABILITY IN BIFOCAL
| INDEX |
|
Clear
|
Color
|
Type
|
Addition
|
Power Range
|
| 1.67 Plastic |
Clear |
D28 |
1.00 to 3.00 |
-15.00D/ +7.00D |
| 1.60 Plastic |
Clear |
C28 |
1.00 to 3.50&4.00
|
-15.00D/ +7.00D
-8.00D/ +8.00D |
| 1.60 Plastic |
Clear |
D28 |
1.00 to 3.00 |
-12.00D/ +8.00D |
| 1.59 Polycarbonate |
Clear |
D28 |
0.75 to 4.00 |
-12.00D/ +9.00D |
| 1.53 Trivex |
Clear |
D28 |
1.00 to 3.50 |
-8.00D/ +7.50D |
| 1.50 CR 39 |
Clear |
C28 |
0.75 to 3.50&4.00 |
-12.00D/ +10.00D |
| 1.50 CR 39 |
Clear |
D28 |
0.75 to 4.00 |
-8.00D/ +7.50D |
| 1.50 CR 39 |
Clear |
D35 |
0.75 to 3.50 |
-7.00D/ +7.00D |
| 1.50 CR 39 |
Clear |
RT28 |
0.75 to 3.50 |
-6.00D/ +7.50D |
| 1.50 CR 39 |
Clear |
Executive/RT 24 |
1.00 to 3.00 |
|
| Transitions |
|
Clear
|
Color
|
Type
|
Addition
|
Power Range
|
| 1.50 CR 39 |
1.53 Trivex |
C28/ D28 |
1.00 to 3.00 |
-8.00D/ +7.50D |
| 1.50 CR 39 |
Grey |
D35 |
0.75 to 4.00 |
-6.00D/ +7.50D |
| 1.53 Trivex |
Grey |
D28 |
1.00 to 3.00 |
-8.00D/ +7.50D |
| Polarised |
|
Clear
|
Color
|
Type
|
Addition
|
Power Range
|
| 1.50 CR 39 |
Grey |
D28 |
1.00 to 3.00 |
-6.00D/ +6.00D |
| 1.50 Polycarbonate |
Grey |
D28 |
0.75 to 3.50 & +4.00 |
-8.00D/ +6.50D |
| Drivewear |
|
Clear
|
Color
|
Type
|
Addition
|
Power Range
|
| 1.50 CR 39 |
Brown |
D28 |
1.00 to 3.00 |
-8.00D/ +7.50D |
| Sunlite |
|
Clear
|
Color
|
Type
|
Addition
|
Power Range
|
| 1.50 CR 39 |
Grey |
D28 |
1.00 to 3.00 |
-6.00D/ +6.00D |
| * Available upto 4cyl. only |
| Acclimates |
|
Clear
|
Color
|
Type
|
Addition
|
Power Range
|
| 1.50 CR39 |
Grey/ Brown |
D28 |
1.00 to 3.00 |
-8.00D/ +7.50D |
| Mineral |
|
Clear
|
Color
|
Type
|
Addition
|
Power Range
|
| 1.52 Glass |
White |
D28/ C28 |
0.75to3.50 |
-8.00D/ +6.00D |
| 1.52 Glass |
PGX/ PBX |
D28/ C28 |
0.75to3.50 |
-8.00D/ +6.00D |
| 1.52 Glass |
White |
RT 25/ RT28 |
0.75to3.50 |
-6.00D/ +6.00D |
| 1.52 Glass |
PGX/PBX |
RT28/ RT28 |
0.75to3.50 |
-6.00D/ +6.00D |
| 1.52 Glass |
White |
Executive |
1.00 to 3.00 |
-5.25D/ +4.00D |
| 1.52 Glass |
PGX/PBX |
Executive |
1.00 to 3.00 |
-5.250/ +4.00D |
| MAX. +6.00 CYL. |
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Lens Type
Based on your prescription, the optician will choose from the following lens types: single-vision or a lens with two, three—or an infinite—range of powers.
Single Vision: This type of lens features one power throughout the entire lens. It is typically for people between the ages of 1 and 40 as it is used either to correct problems with distance or for special needs, including magnification. A single-vision lens can also be used for reading only.
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Bifocal: A bifocal lens is equipped with two ranges of power—far and near. Bifocals are easily recognized by the line that separates the far range from the near range. For this reason, it is sometimes referred to as a line bifocal.
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Trifocal: As the name implies, a trifocal lens has three, separate ranges of power—far, intermediate and near—marked by two, distinct lines. Like the bifocal, it’s easy to see the lines that differentiate between the three ranges.
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Progressive: Blessed with an infinite number of focal points, this type of lens changes gradually so that it can adjust to a wide variety of distances. As a result, the user can see far, intermediate and near distances without any lines of demarcation.
