■Foreword: Color contact lenses are not a generic name for a product, they are a registered trademark exclusively owned by Johnson & Johnson (registration number: 4233189). The correct product name for "color contact lenses" as understood by ordinary consumers should be "color so

■ Foreword: Color contact lenses is not a generic name for a product, it is a registered trademark exclusively owned by Johnson & Johnson (registration number: 4233189). The correct product name for "color contact lenses" as understood by ordinary consumers should be "color soft contact lenses". To facilitate readers’ easy understanding, “color contact lenses” in this article refers to “color soft contact lenses”.

During the normalized prevention and control stage of the epidemic, everyone wears a mask most of the time when going out, with only half of their face exposed. Eyes have become a key area of ​​beauty makeup, and colored contact lenses have also become a popular consumer product.

At the same time, more and more young people with myopia are using colored contact lenses to correct their vision. They may think that since I have to wear glasses anyway, contact lenses with myopic power can make me more beautiful!

Picture source: Tuchong Creative

After noticing this phenomenon, " Consumer Report " launched a consumer survey on color contact lenses, and conducted a survey on the oxygen permeability of 6 brands of color contact lenses and ordinary contact lenses of the same brand. Compared.

Color contact lenses from Kerala, Bausch & Lomb, Hailien each have low oxygen permeability and are not recommended for long-term use.

A healthy cornea has no capillary distribution. When the eyes are open, the cornea maintains basal metabolism. The required oxygen 80% comes from the outside air, 15% comes from the corneoscleral blood vessels, and 5% comes from the aqueous humor. When we wear contact lenses, it is equivalent to adding a "barrier" between the cornea and the air, blocking the transmission of some oxygen. So in theory, the higher the oxygen permeability of contact lenses, the better.

From a classification point of view, both cosmetic lenses and ordinary contact lenses belong to "contact lenses". For the sake of eye health, we also need to focus on the oxygen permeability indicator when choosing contact lenses, and have a basic understanding of the difference between oxygen permeability coefficient and oxygen permeability.

This time, "Consumer Reports" compared 6 popular contact lenses on the market with the corresponding ordinary contact lenses sold by their respective brands on the parameter of oxygen permeability.

From the data, some contact lenses have low oxygen permeability. The oxygen permeability of one color contact lens from , Bausch & Lomb, Kerala is less than half of that of ordinary contact lenses from their own brands.

Optometry product salesperson Li Hua (pseudonym at the request of the interviewee) revealed to reporters that compared to ordinary contact lenses, color contact lenses have more pigment layers, and the oxygen permeability is usually not very high. However, the reporter found that the oxygen permeability of Johnson & Johnson , moody, and Haichang color lenses can be at least equivalent to that of ordinary contact lenses.

At present, my country’s national standards do not set requirements for the minimum oxygen permeability of contact lenses/contact lenses.

In 1984, after experiments on a large number of hydrogel contact lenses and silicone lenses, Brien Holden and George William Mertz, pioneers in the field of modern optometry clinical research and vision care research, discovered that if daily wear is adopted, corneal edema will not occur if corneal edema is not caused. , the minimum oxygen permeability Dk/t value of contact lenses should be 24×10-9 (unit is (cm/s) [mLO2/(mL·mmHg)], the same below). More importantly, Holden and Mertz found that in order to keep corneal edema below 4% by wearing lenses overnight, the minimum oxygen permeability Dk/t of the contact lens should be 87×10-9.

A subsequent study pointed out that when people sleep without wearing glasses, the average corneal edema rate is 3.2%. According to the regression curve analysis of oxygen permeability and corneal edema by Holden and Mertz, wearing glasses overnight has the lowest rate of contact lenses. The oxygen permeability Dk/t should be 125×10-9.

While these values ​​are not mandatory limits, they are recognized by optometry industry organizations such as the International Association of Contact Lens Educators.

In other words, When consumers choose contact lenses or contact lenses, it is best to choose products with oxygen permeability Dk/t value above 24×10-9; if there is a need to wear them overnight, it is best to choose Dk Products with /t value above 125×10-9.It is worth reminding that the reporter noticed that in the instructions for contact lens/color lens products, the unit of oxygen permeability is generally (cm/s) [mLO2/(mL·hPa)]. To judge whether the value meets the above recommendations, you need to The unit is converted into (cm/s) [mLO2/(mL·mmHg)].

Oxygen permeability indication on the product manual of color contact lens

Unit conversion:

1(cm/s)[mLO2/(mL·hPa)]=0.75(cm/s)[mLO/(mL·mmHg)]

Wearing oxygen permeability Low dosage or long-term wearing of contact lenses/contact lenses may cause corneal hypoxia. Eye hypoxia will cause conjunctival congestion , and corneal epithelial cells will also be affected, weakening the resistance. If there is long-term lack of oxygen, surrounding tissue will grow new. Blood vessels enter the cornea and supply the cornea with blood, which is " corneal neovascularization ".

Picture source: Lilac Life Research Institute

In addition, Shi Weiyun, the director of Shandong Provincial Eye Hospital, once publicly stated that he would encounter a large number of eye complications caused by wearing colored contact lenses in clinical practice. Because the contact lenses are worn on the cornea, there is a risk of the cornea becoming infected. Once infected, the cornea may become cloudy and the vision may be irreversibly reduced. It may also cause corneal hypoxia. He particularly emphasized that it is not recommended for young people to wear contact lenses, especially low-quality contact lenses. After being soaked in tears, the toxic coloring materials are harmful to the eyes.

At the same time, he suggested that people who wear contact lenses or contact lenses should pay attention to eye hygiene, especially when wearing glasses. When necessary, you can follow your doctor's advice and use artificial tears or antibiotic eye drops to reduce the complications of wearing glasses.

If you want good oxygen permeability, you can give priority to silicone hydrogel contact lenses/color lenses

In fact, If you want to get higher oxygen permeability, consumers can focus on silicone hydrogel products , there are many tiny oxygen channels in the matrix of silicon, its main component, which allows oxygen molecules to pass through the lens relatively freely, maintaining good oxygen permeability; on the other hand, it is hydrophobic, so that the oxygen permeability of the lens does not have to be affected Moisture content limitations. For ordinary hydrogel lenses, the water contained in them is the main carrier of oxygen. Theoretically, the higher the water content, the higher the oxygen permeability. However, in order to maintain moisture content, the lenses need to absorb water from tears, which can easily cause dry eyes when worn. Some studies have pointed out that silicone hydrogel lenses can significantly improve dry eye syndrome caused by hydrogel lenses.

Generally speaking, silicone hydrogel products have better oxygen permeability than ordinary hydrogel products. Consumer Reports also collected some information about silicone hydrogel products on the market. They generally have high oxygen permeability, but the price is correspondingly higher.

It is worth mentioning that compared with ordinary hydrogel, silicone hydrogel is relatively hard, and some wearers may need some time to adapt.

Color contact lenses belong to the "third category of medical devices", and the product packaging is printed with the "Medical Device License Number"

Li Hua said that many contact lens agents and consumers have not established the basic understanding that "color contact lenses are medical devices" . They think that contact lenses are just cosmetic products, and they just need to look good.

In fact, the product names of cosmetic contact lenses on the packaging are generally "color soft hydrophilic contact lenses" and "soft corneal contact lenses". According to the medical device classification catalog of the National Medical Products Administration , it belongs to the third category of medical devices.

Colored soft hydrophilic contact lenses and soft corneal contact lenses belong to the third category of medical devices

According to the provisions of Article 4 of the General Provisions of the "Measures for the Supervision and Administration of Medical Device Operations", according to the degree of risk of medical devices, medical device operations are subject to classified management. The operation of Class I medical devices does not require licensing and registration, the operation of Class II medical devices is subject to registration management, and the operation of Class III medical devices is subject to licensing management.

In other words, cosmetic contact lenses are not ordinary cosmetics consumer products, they belong to the third category of medical devices with a higher degree of risk.Consumers must pay more attention when purchasing. They must first confirm whether the product they want has the " medical device registration certificate number". This number is usually printed on the product packaging, and then log on to the official website of the State Food and Drug Administration to check this number. Does it correspond to the product you purchased and whether the number is within the validity period.

State Medical Device Administration Medical Device Query Column

Enter the product registration certificate number to query detailed information

The eyes are the windows to the soul. More than 80% of external information is input to the human body through the visual pathway. Therefore, we must be kind to our eyes.

For consumers, "Consumer Reports" does not recommend wearing contact lenses for a long time at a time, nor does it recommend that people use contact lenses as a tool to correct vision for a long time. Before purchasing contact lenses/color lenses, you should go to a regular medical institution for an eye medical examination to confirm whether you are suitable for wearing such products. Before fitting, the corneal curvature and corneal diameter need to be measured to confirm the base arc and diameter of the adapted lens.

For manufacturers of contact lenses, Consumer Reports calls on them to clearly indicate the oxygen permeability of contact lenses on the packaging box or on the promotional page. Because most products are only labeled on the inner box or instruction manual, and the products themselves are packaged in plastic, it is difficult to give consumers clear guidance when purchasing.