The Truth About Contact Lenses Materials: Hydrogel, non-ionic, and silicone hydrogel
Apr 11,2022 | Lensweets
As a girl who loves makeup, colored contact lenses are indispensable on the dresser. Sometimes we buy the same type of colored contact lenses as our friends, only to find our eyes are dry and red after wearing them for a day, but our friends do not have the same discomfort! This is because we do not know enough about the materials of the contact lenses and choose product that is not suitable for our eyes.
The material of the colored contact lens is closely related to oxygen permeability, and the suitable material can make you have a comfortable wearing experience. So, what are the differences between different materials? This article will answer your questions.
The Most Widely Used Hydrogel Material
Our eyes, like our bodies, cannot live without water. Hydrogel is a soft material that loves water, so it is ideal for making contact lenses. “HEMA” that marks on the packaging or instructions of many products is traditional hydrogel material. This material is soft, comfortable, and affordable. It has various applications, such as daily, monthly, and yearly disposable contact lenses.
Hydrogel materials need to transmit oxygen through water, so the higher the water content, the better the oxygen permeability. Meanwhile, the ability of protein resistance will be worse. Therefore, the water content of the yearly disposable lenses is basically between 38% and 42%, which can reduce the protein deposition and prolong the service life.
However, the higher the water content, the better the oxygen permeability, which does not mean that high water content is better. If you are a person who has less tear secretion, faces the computer for a long time, or lives in a low-humidity area, your eyes will feel dry after wearing it for a long time. This is because the water in the contact lenses will evaporate quickly during the day’s use and even absorb the tears secreted by the eyes in reverse. In this case, you should try to choose lenses with a lower water content to reduce dry eyes after long-term use.
It is worth noting that the non-ionic material that many people think is a brand new material is actually a kind of hydrogel. Due to the addition of a monomer called NVP, the hydrogel material becomes a non-ionic hydrogel. It is relatively lighter, thinner, and more resistant to protein precipitation.
Preference for Sensitive Eyes: Silicone Hydrogel
If your eyes are particularly sensitive, then silicone hydrogel lenses will be more suitable for you. Since silicone is polymerized based on hydrogel, the silicone hydrogel material has both the softness of hydrogel and the high oxygen permeability of silicone.
Unlike hydrogel lenses, the oxygen permeability of silicone hydrogel lenses depends on the amount of silicone used, not the water content. The oxygen permeability of silicone hydrogel lenses can reach 5 to 6 times that of hydrogel lenses. But also, because of the strong adsorption capacity of silicone hydrogel, oil and protein are more easily deposited on the lens. Therefore, silicone hydrogel is not suitable for cycle use. Currently, there are only daily, semi-monthly, and monthly disposable silicone hydrogel contact lenses.
The short usage cycle and the high price make the cost of using silicone hydrogel lenses very high. If your eyes are not particularly sensitive, then FDA-approved hydrogel lenses are good enough to meet your needs at an affordable price.
In a word, there is no best material, only the most suitable material. Through the study of this article, I hope that you will no longer blindly pursue a specific material but choose according to your own eyes situation.