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Considering contact lenses? The basic types of contact lenses

Contact lenses can fulfil several functions. As a corrective solution for vision problems contact lenses can remove the need to wear glasses, either altogether or simply during sporting activity. Wearing contact lenses as opposed to glasses can also allow experimentation with a new style. Since the first contact lenses were introduced to the mass market in the mid 20th Century, the number of materials used to construct these products has grown, producing ever more variations with different benefits for the wearer to get a look at the range of contact lenses now available online, take a look at: visiondirect.co.uk. Here we will take a look at the basic types of contact lenses.

The original contact lenses were made from a type of hard plastic called PMMA (polymethyl methacrylate). This type of contact lenses are rarely used now, mainly because the material does not let any oxygen pass directly through to the cornea, which can potentially cause a range of problems. When these lenses are worn they move when the eye blinks, and thanks to this movement oxygen dissolved in the tear film can then reach the cornea. The main advantage of PMMA lenses are that they are very durable, and can produce better visual acuity (sharpness of vision) for wearers with some types of corneal astigmatism. However, PMMA lenses are the least comfortable of all the options, and have almost entirely been replaced by RGP (Rigid Gas Permeable) lenses.

Rigid Gas Permeable lenses, as the name suggests, do let oxygen pass through to the cornea. This can help prevent a range of issues from mild irritation to serious infection of the eye developing. RGP contact lenses were first introduced in the late 1970s, and since then the development of new materials has continued, producing more and more comfortable RGP contacts each year. Like PMMA lenses, RGP contacts have the advantage that toxic or allergic reactions to cleaning solutions are less common - than with some soft contact lenses - due to the fact that RGP lenses do not absorb preservatives and disinfecting agents in the solution.

Soft contact lenses are by far and away the most popular option today, with around three quarters of wearers using soft contact lenses. Soft contact lenses are made of advanced plastics that contain lots of water, and are generally regarded as the most comfortable contacts. A large part of the reason for this is that soft contacts mould to the shape of the eye, but this also means that these lenses cannot be used to correct all conditions. As this technology has developed, the possible wear time for some of the newer soft contact lenses has extended some continuous or extended wear contacts can now be worn for between a week and a month at a time without removal. However, many soft lenses still require daily removal and cleaning, and it is important to follow the guidelines provided by your eye doctor when taking care of these contacts. Many people who wish to avoid this process now wear daily disposable contact lenses, which are thrown away after a days use. More information on the safe wearing of contact lenses can be found here:http://www.nhs.uk/Livewell/Eyehealth/Pages/Contactlenssafety.aspx.

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