Optimal wearing contact lenses in the daytime, and at night they should be removed. But there are times when you simply need long wearing, including at night. For example, young children or older people, travellers, young people who attend Nightclubs.
To do this, and were invented konechnye use extended wear lenses that can be worn at night. They assume continuous use for up to 30 days.
But it is necessary to bear in mind the fact that the lens prevents the full coloradoonline eyeball with the environment, which can lead to swelling of the cornea. That's why the lens extended wear with high gas permeability, and the center of the lens must have a small thickness.
Choosing lenses should be deleted too steep landing. The mobility of the lens on the eyeball needs within 0.5 -1 millimeters that will keep underneath the required amount of lacrimal fluid.
Contact lenses to be worn for a long time are of two types: silicone-hydrogel and rigid gas-permeable.
The first type is very soft, combines comfort and kislorodoprovodov silicone. In addition, the silicone prevents protein deposits on the lenses, which increases its safety.The first silicone hydrogel lenses were supposed to wear them for up to 7 days continuously. Modern lenses are allowed to be used for 30 days.
The second type is also allowed for long-term use, they are very well allow oxygen, but rigid in its structure and not quite comfortable. There in their use and limitation is their individual intolerance, which may be caused by the stiffness of the material, giving the feeling of a foreign body.
Pros lenses extended wear:
- Do not need every day to change lenses;
- Affordable price;
- Unlike glasses - do not affect a person's appearance;
- Do not scratch and do not sweat;
- You can use people with a difference in the eyes of more than 2.0 diopters;
- Peripheral vision is not limited.
Disadvantages in wearing lenses for a long time:
- Upon contact with the cornea can cause diseases;
- You need regular visits to the ophthalmologist;
Together with the lens in the eye can get the mote, which will bring discomfort. Have to re-wear the lens;
- Inability to use colds and other diseases.
And yet, no matter how safe and convenient it was not wearing lenses extended wear, be sure to contact your doctor.