Technology using lenticular lenses has persisted for over a century. The use of these lenses in print means that a surface has many magnified lenses, allowing the image to be magnified differently depending on viewing location, as with a hologram. Recently, this technology has been utilised in 3D televisions and gaming systems. Manufacturers have also used lenticular technology in eyeglass lenses to combat extreme vision problems and help those who require two different corrective powers.
Lenticular Lens Design
When used with eyeglasses, lenticular lenses typically feature only two different magnifications. One area of the lens has one refractive correction power, while the other area of the lens features a different power. It is typical with lenticular lenses for a pupil-sized circle in the centre of the lens to be one power, while the outside edge of the lens is another. Which area has a stronger power depends upon the type of condition eye doctors wish to correct.
Lenticular "high-plus" lenses have a central area with a higher power than the outside of the lens. They often have a trifocal lens with 10-to-15 dioptres in the centre, making this area quite thick, while the rest of the lens remains thin enough to fit in the glasses frame. This design gives the wearer the appearance of having larger-than-normal pupils. High-plus lenticular lenses were most often used with people that had very poor nearsighted vision. They were also used to help cateract patients see before surgical implant lenses were available.
The inversion of high-plus lenticular lenses, high-negative lenses instead have a lower power in the centre of the lens and a higher power at its sides, making the middle of the lens thin and the outside thick. Consequently, a wearer's pupils look smaller than usual. These lenses are used for patients with extreme problems seeing objects at a distance, and thus require at least a minus-10 dioptre correction. Though some companies still offer these lenses, most patients can usually find an alternative that doesn't distort the appearance of the wearer's pupils.
Another kind of lenticular lens is the bifocal, invented in the late 1700s. These lenses are not necessarily for patients with extremely poor eyesight; instead, they are for patients with both near-sight and far-sight problems. Typically, the upper region of these lenses aids in seeing at a distance, while the bottom portion of the lens helps with nearsighted vision. Advances in technology have allowed for bifocal contact lenses and even lenses that can change power at the push of a button.
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