Contact lenses are popular nowadays that many people use them to correct vision defects as well as get natural appearance
. Some other contacts wearers simply get bored with eyeglasses. There are a huge variety of contact lenses on the market. But rigid and soft gas permeable lenses are the two chief types.
The old term hard contact lenses were used to describe contacts made from a certain semi-plastic compound. Nowadays, rigid gas permeable (RGP) lenses are more popular, which also allow oxygen to go through the lenses. Hard contacts are prescribed and worn less and less today. One advantage of hard contact lenses is worth mentioning that they are the best for vision correction.
Rigid gas permeable contact lenses are made of a special kind of flexible plastic. While allowing a certain degree of discomfort, rigid gas permeable contact lenses require a short time to adapt to. RGP lenses are now incorporated with gas permeable features. But they are still long lasting and hardy. The most important benefit of RGP lenses is sharper vision they can provide.
Another type is soft contact lenses. The material of soft contact lenses is special plastic consisting 80% water. With this composition, soft contact lenses are much more comfortable than RGP ones and require little time of adaption at the side of a wearer. This is the striking advantage of soft lenses. Soft contact lenses can be further divided into two types: extended ones and disposable ones. The former type allows wearers to keep lenses overnight. And the latter type should be discarded after a certain period.
There are still some special contact lenses for particular use. For instance, toric lenses in either RGP or soft type are exclusively designed for astigmatism correction. Moreover, bifocal lenses are extremely suitable for people with presbyopia. And novelty wear contact lenses without any pathological prescription are used to change the eye color.