Contact lenses, a comparatively frequent vision accessory now, are being increasingly used by people who have simply got bored or too tired using spectacles. Among the different kinds of contact lenses, the chief types are rigid and soft gas permeable contact lenses. However, the earlier ‘hard’ contact lenses are not frequently prescribed by physicians today, and yet less is their use today.
1. Hard Contact Lenses: Contact lenses made from a certain semi-plastic compound, but those which still allow oxygen to permeate through them are called RPG lenses or Rigid Permeable lenses. They are being used less and less today. But there is one thing about Hard Contact lenses today; they are best equipped for the treatment of certain optical problems, namely the correction of vision problems. For the user longing for clearer vision, hard contact lenses are still the best option.
2. Soft Contact Lenses: These are another type of contact lenses, newly developed, for specialized purposes. They are commonly made up of a type of plastic consisting of 80% water. The striking feature of these lenses is the level of comfort they offer. They are extremely soft, and this is what precisely contributes to the comfort-but their softness can also lead to accumulation and retention of impurities such as grime with long periods of wearing them. Among these lenses, there are two types: Extended ones allow the user to wear them overnight, and the Disposable contacts are to be thrown away after a specified period of wearing, and the user has to take a new lens. This means when he is using them, he is kept supplied all the time with a fresh set of lenses.
Among the RGP contacts, the eye-piece is made of a special kind of flexible plastic, which allows a certain degree of discomfort when they are initially worn, but the eye rapidly adapts itself to the unease and gets accustomed. As mentioned before, they provide sharper vision in most cases than soft contacts, are much more long-lasting and hardy. This means that they are more expensive per lens too. Extended contacts are also available in the RGP form, allowing for overnight wear.
For astigmatism, Toric lenses are needed, and they can be had both as RGP and soft contacts. The specially designed lenses are equipped with a sort of curvature which lets them to be fixed at one particular eye-region. Toric lenses work best in treating astigmatism- they are successful even in the most extreme cases, but there are other lenses to treat astigmatism too.
Bifocal lenses can also be had as both RGP and softer makes. The aim of these lenses is to simulate the bifocal vision offered by glasses i.e. a part of the lens works for nearer vision and the other part for viewing distant objects. The eye has to be given some time to adapt itself to such lenses, but in case they still do not seem suitable, the bifocal effect can be simulated by using one lens designed for distant vision and one for nearer vision purposes.
Novelty Wear contacts that are worn without any pathological prescription are designed to give a certain color to the eye-sapphire, blue, green, brown and many more.
Extended Wear contacts are those lenses that could be worn for long stretches of time without having to remove them at all. For best results, they should be changed annually with regular visits to the opticians for vision correction. They are available in both RGP and soft lens varieties.
