Second, the classification of contact lenses Contact lenses are divided into transparent films and color films. Transparent film is our conventional contact lens, and color film is our conventional beauty contact lens. There is no difference between them except whether they print patterns or not.
transparency
colour film
I know that basically all primary school vendors are constantly trying to blur the relationship between cosmetic contact lenses and the third kind of medical devices, constantly brainwashing consumers, and making consumers feel that cosmetic contact lenses are a very common commodity, just like double eyelid stickers! However, it is not!
Legal cosmetic contact lenses and contact lenses must be registered on the website of the Food and Drug Administration. If you can't find it, it's three no products, even if the pattern is beautiful, don't buy it!
The production and manufacturing cost of inferior illegal contact lenses is very low, and the cost of a pair of contact lenses and beauty contact lenses may be only a few dollars. After wearing the eyes, the damage to the eyes is very, very great, ranging from dry eyes to blindness!
Third, the materials of contact lenses The materials of contact lenses mainly include hydrogels and silicon hydrogels.
Silicone hydrogel
hydrogel
At present, the over-touted non-aqueous ion on the Internet is actually a hydrogel material.
A very important concept to be mentioned here is oxygen permeability, which is the most important index to test the quality of lenses.
We all know that there are no blood vessels on the cornea, and all the oxygen comes from tears, eyelids and the outside air. Oxygen permeability determines the possibility of oxygen reaching the cornea through the lens.
People who often wear contact lenses should know that you can't sleep with contact lenses. If he sleeps carelessly with invisibility, his eyes will be particularly uncomfortable and blind after waking up. This is the problem caused by low oxygen permeability. The oxygen permeability of traditional hydrogel materials is about 20 days, which can only support oxygen in the open state. When you close your eyes, the cornea lacks oxygen, so something must have happened!
Traditional hydrogel contact lenses have low oxygen permeability, and they are basically thrown in seasons and years. Long-term wear can easily lead to dry eye, corneal thinning, conjunctivitis and other problems.
The oxygen permeability of silicon hydrogel is 6-8 times that of hydrogel material, which is more suitable for wearing for a long time. Take a nap in the middle school, and I personally think it's okay.
By the way, many foreign countries have banned the production of contact lenses that throw more than a month. Contact lenses have been worn for a long time, and the impurity corrosion is becoming more and more serious, and the oxygen permeability is getting lower and lower, which is more and more harmful to glasses! Therefore, it is not recommended that you buy contact lenses that have been thrown for more than one month.
At present, the longest silicone hydrogel contact lens and cosmetic contact lens is the moon-throwing. Personally, I suggest buying contact lenses and beauty contact lenses with silicone hydrogel as much as possible when the economy permits.
Let's talk about the classic marketing scam of contact lens industry in Korea: it is to add some silicon to hydrogel materials, so it is called silicon hydrogel! This is a big lie of a century! Adding some silicon to hydrogel is essentially hydrogel, which only improves the comfort of wearing, but can not improve the oxygen permeability at all!
Silicon hydrogel represents a revolution in contact lens materials, which is not as simple as adding silicon to hydrogel, but represents high oxygen permeability! At present, the patented technology of silica gel hydrogel is in the hands of four major companies, without Korea! Don't lick Korea too much, where is Korea's leading technology!
To judge whether a pair of glasses is a real silicone hydrogel, you can check the oxygen permeability in the product manual. If the oxygen permeability is lower than 120, it is a hydrogel! South Korea's so-called silicone hydrogel contact lens, can you show your oxygen permeability and see if it meets the standard!
You may have tried the invisibility of silicon hydrogel before, or you may have just bought a pseudo-silicon hydrogel material packaged by adding some silicon to the hydrogel!
IV. Selection of Silicone Hydrogel Contact Lens At present, there are four companies holding patents on silicone hydrogels, namely Alcon, Bosch Lomb, Johnson & Johnson and Cooper. Unfortunately, there are no Chinese, Korean and Japanese ones.
Bausch and Longbu
Kubo
At present, in addition to the four companies mentioned above, there are other brands that produce silica gel hydrogel transparent sheets, such as Merocon in Taiwan Province Province (there may be other brands).
The color film (beauty contact lens) brands that produce silicone hydrogel are Shikang and Merocon (there may be other brands).
I know that most contact lens brands are constantly trying to rely on silicone hydrogel materials, but it seems that the direction is wrong. Instead of trying to reach the standard of silica gel hydrogel in material technology, they made an article on packaging publicity.
To judge whether a pair of glasses is a real silicone hydrogel, you can check the oxygen permeability in the product manual. If the oxygen permeability is lower than 120, it is a hydrogel!
I declare here that as long as there is HEMA on the packaging material, it is a hydrogel material. No matter how gorgeous the packaging is, it can't change the fact that it is hydrogel.