Single Vision Lenses (SV)
Single vision lenses have the same focal power throughout the entire lens and can be used to correct myopia, hyperopia, and astigmatism. Single vision lenses are usually used by eyeglass wearers under the age of 40. At Broadbent, we provide a wide range of single vision lenses that will not only meet your needs but offer you the utmost in cosmetic appeal.
Bifocal lenses used to be the only option for people with presbyopia who also require a correction for myopia, hyperopia and/or astigmatism. They are lenses that carry two distinct optical powers in each lens, separated by a visible line. Midrange vision (at arms length) is compromised as there is no set correction for that distance in a bifocal. A trifocal includes a section dedicated to midrange vision. The bifocal is an old technology as progressive lenses are now the new option for better aesthetics and comfort.
Multifocal (Progressive) Lenses
Progressive lenses are also designed to counter presbyopia – a condition that usually develops around the age of 40, where one has difficulty focusing on near objects. They correct the effects of presbyopia with a gradual change of power from near to distance vision, restoring natural vision without the unsightly segmentation lines or image jump experienced with standard bifocals. Progressive lenses offer comfortable vision at all distances.
LENS MATERIALS AND COATINGS
Among the high index materials developed for eyeglasses, there is one material that has a number of very unique properties and that also provides special benefits to eyeglass wearers. It carries the generic name “polycarbonate” but is sometimes referred to different manufacturer trade names. It’s great for sports eyewear, protective, a “must” for kids, and includes Scratch and UV Protection.
The benefits include:
- Impact Resistance – Polycarbonate lenses are 10 times more impact resistant than plastic lenses
- Lighter – Polycarbonate lenses are up to 35% lighter and thinner than standard plastic lenses for greater comfort
- UV Protection – Polycarbonate lenses shield your eyes from virtually 100% of the sun’s harmful UV rays
- Scratch Resistance – PolyCarbonate lenses are hardcoated for excellent durability and scratch resistance
- Easy care
After polycarbonate comes the “high index” materials. These are all plastic lenses with indexes of 1.6, 1.67, 1.7 and up to 1.74. 1.74 is the thinnest plastic lens available. Typically, the higher the index of the lens material, the more expensive it is, but cosmetically more attractive. When opting for hi-index lenses, it is recommended to choose a full rim plastic frame. This is a tip for those who are near sighted seeking to reduce edge thickness. While not actually reducing lens thickness, by choosing a plastic frame much of the thickness can be hidden. Compared to a thin metal frame or rimless style, a plastic frame can provide quite a bit of camouflage at the edges.