There are contact lenses of various types. However, some people can not wear certain ones due to their special eye conditions. Usually, which ones are to wear will be decided by the eye doctors who have a much better idea about this. Different lenses vary a lot in materials, duration, transparency and functionality.
If judged from materials, contact lenses can be fallen into two groups, say, soft lenses and hard lenses. The former type is gas permeable and can maintain sufficient moisture. The moisture in it also varies a lot. On the contrary, the later type is made from durable materials and can let gas through as well.
Of course, different lenses can be worn for different duration. Such as, the hard series can be worn for several months if maintained and cleaned properly. On the contrary, the soft series can be worn for much shorter time- some of them must be replaced daily, weekly or monthly. Or there are still some lenses that can be slept in at night, which are still in need of careful maintenance.
Usually, lenses can be designed in three major forms, namely, toric, spherical and multi-focal. Each of them is suitable for wearers with particular vision problems. Such as, toric is used for astigmatism correction; spherical lenses is for short or long sightedness; multi-focal for presbyopia. Therefore, people should consult with their eye doctors before deciding which ones to buy.
The reason why people use lenses varies a lot, including optical, therapeutic, cosmetic and decorative purposes. If people have some vision problems to be rectified, optical lenses are ideal. If people are receiving medical therapy, therapeutic lenses are suitable. If people want to change their eye color, cosmetic lenses can be used. As for decorative lenses, they are mainly used for fun and entertainment. Therefore, people should consult with their eye doctors if they really want to wear lenses, so as to avoid mistakes, which may lead to serious eye damage.
In a word, people are strongly suggested to consult with their eye doctors in determining which lenses to buy, according to their personal needs. In addition, it is urgent to know something more if they really want to wear lenses.