Those who wear contact lenses for a long time know well how tired their eyes are towards evening. This happens, first of all, because of poor access of oxygen to the cornea. Silicone-hydrogel lenses solve this problem completely - unlike conventional soft hydrogel lenses, they allow the eyes to fully participate in oxygen exchange.
The best brands producing silicone-hydrogel lenses
The water content of hydrogel and silicone-hydrogel contact lenses is approximately the same, but the index Dk / t is the ratio of oxygen permeability to lens thickness in the center - the latter can be several times higher. For example: PureVision lenses from Bausch & Lomb from silicone hydrogel have Dk 110, and hydrogel lenses of the same American firm, but from the series SofLens 59 can boast a coefficient of oxygen conductivity of only 16.5. Both those and other lenses are designed for a monthly replacement.
The most high-quality lenses from silicone hydrogel are available from large manufacturers:
- Ciba Vision;
- Alcon;
- Bausch & Lomb;
- Cooper Vision;
- Zeiss.
They have a line of one-day silicone-hydrogel lenses and lenses for long-term wearing. Due to the high Dk values, it became possible to continuously wear contact lenses for several months. Now you can not remove the lens at night without any damage to the eyes. The solution for silicone-hydrogel lenses does not differ from usual.
Color silicone-hydrogel lenses
Due to the fact that the tinted contact lenses contain a pigment, their ability to conduct oxygen is significantly reduced. Even by adding silicone to the hydrogel, the problem can not be completely solved - color lenses can not be worn for longer than 12 hours in a row. Nevertheless, they are much more pleasant before our eyes. The most popular color lenses from silicone hydrogel - Air Optix Color from the American company Alcon.