Contact lenses can be divided into hard contact lenses and soft contact lenses according to the material. What are the similarities and differences between these two types of contact lenses?
Hard contact lenses are mainly made from polymers such as fluorosilicon, which have good oxygen permeability, do not deform, and have a long service life. But according to the experience of wearing, it is not as comfortable as soft mirrors, so it takes a long time to get used to. Rigid speculums usually need to be put on at night during sleep and removed the next morning, as they can change the curvature of the cornea and maintain a corrective effect.
Materials for soft contact lenses are mainly divided into two types: hydrogel and silicone hydrogel. Both hydrogel and silicone hydrogel are organic polymers with high hydrophilicity, they are soft and easy to deform, making them more comfortable to wear. However, the oxygen permeability of hydrogel lenses will be limited by their water content, so wear time must be controlled to avoid corneal hypoxia. Silicone hydrogel lenses are designed by adding hydrogel-based silicon molecules, so there is a breakthrough in oxygen permeability. The biggest disadvantage of silicone hydrogel may be that the lens is slightly stiffer and the foreign body sensation is more obvious, resulting in a corresponding increase in the time it takes for the eyes to adapt.
The material of a contact lens is very important, it can directly determine the oxygen permeability of the lens. Generally speaking, the higher the noted DK value, the stronger the oxygen permeability of the lens. Therefore, if you wear contact lenses for a long time, it is necessary to choose lenses with the highest possible oxygen permeability.
Another thing to note is that no matter what kind of contact lenses you wear, you must pay attention to cleaning and care so as not to affect lens life and eye health.