What should You Know about Hard Contact Lenses?

For years, contact lenses were known as hard contact lenses. They first entered the market in 1940s and were made of organic glass. At present day, this material is rarely used even though organic glass is firm, rather cheap, and characterized by a good transparency. The main drawback of this material is low oxygen permeability. In modern eyesight improvement hard gas-permeable lenses are used. These hard lenses are more flexible, characterized by a good transparency and a high oxygen permeability which is the most important criteria for people choosing contact lenses.

A fundamental defect of contact lenses is long adaptation period and possible discomfort at wearing them. As a result, most of patients who chose hard contact lenses at first have rejected wearing them later. However, if the person got used to hard contact lenses, he/she may benefit from using them, as, contrary to soft contact lenses, hard contact lenses enable to see better, they are cheaper, more longeval and they require less daily attention. Hard contact lenses life time is 7 years and more. Hard contact lenses, as opposed to soft ones, can be polished in case any scratches appear and may be corrected in case a patient gets new prescription from his/her doctor.

At first, hard contact lenses are felt as a foreign body in the eye. If hard contact lenses are chosen and fit properly, this discomfort disappears little by little. During the first weeks of wearing hard contact lenses you may have overwetting in the eyes and you may see indistinctly, but you will forget about it soon.

Most patients get used to hard contact lenses – to feel comfortable they wear them every day. If you wear hard contact lenses for 12 hours a day and then make a break for a while, you will have to adapt to them again. Firstly, hard contact lenses are worn 4 hours a day, then, this time is increased.

If you wear hard contact lenses more than 14 hours a day, you may face different problems related to oxygen supply of cornea. As opposed to other organs, cornea is deprived of blood vessels. Cornea is highly dependent on oxygen and cornea prevents oxygen supply. Partially, this problem is solved in the following way: with every wink, hard contact moves and a new tear rich of oxygen enters the space between the lens and the cornea. However, this is not enough to supply cornea with oxygen to full extent. After wearing hard contact lenses for several hours cornea cells start swelling because of oxygen shortage. Cornea edema causes discomfort which leads to the cloudy visibility. As a result, a patient can refuse wearing hard contact lenses and start wearing glasses again.

Discomfort and cloudy visibility are ruled out with the hard gas-permeable lenses mentioned above. The material they are made of can absorb oxygen and other gases. One can wear lenses of the kind all day long – without any discomfort or bad visibility. Due to high moisture content of their material, gas-permeable hard contact lenses are easily adjusted to and, therefore, are more welcomed by the patients.

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