Precautions for wearing contact lenses

　　When wearing contact lenses, attention should be paid to the following points:　　1. Before wearing contact lenses, it is important to ensure that the eyes are not congested or visibly dry, and that there is no discomfort. Only then can contact lenses be worn.　　2. Before wearing contact lenses, it is necessary to wash hands with soap and then take out clean contact lenses to wear. If there is a foreign body sensation or pain in the eyes after wearing contact lenses, be sure to remove the lenses and do not wear them temporarily. At this time, frame glasses need to be used to correct vision. We still need to go to the hospital for a check-up to rule out any issues such as keratitis.　　3. Contact lenses should not be worn for more than 8 hours during the day, as wearing them for too long can cause hypoxia in the cornea, which can easily lead to the shedding of corneal epithelial cells. Therefore, the time for wearing contact lenses should be shortened as much as possible.　　4. After removing contact lenses, be sure to clean them thoroughly and soak them in a care solution. Try not to wear contact lenses every day and minimize the time and days of wearing them.　　5. People with contact lenses need to prepare a pair of frame glasses for alternate use.

Common knowledge of contact lens production categories

　　Contact lenses have various classifications in terms of production materials, service life, moisture content, center thickness, etc. Due to the large number of lens parameters, more detailed classifications are also made to facilitate wearers to choose according to their needs. Today, we will introduce the types of contact lenses from three common categories: manufacturing materials, usage cycle, and water content.　　According to the production materials, contact lenses can be divided into hard contact lenses and soft contact lenses. Hard contact lenses have a harder texture and are less prone to deformation. They can be corrected by changing the shape of the cornea, also known as night wear lenses, and can be worn while sleeping. The texture of soft contact lenses is very soft. Due to their easy shape change and high water content, they are more comfortable to wear right away and do not require a long adaptation time. Soft contact lenses can be divided into hydrogel and silicon hydrogel according to their materials. As can be seen from the name, both materials belong to organic polymer substances, but silicon hydrogel belongs to the upgraded version of hydrogel, and its oxygen permeability is dozens of times that of hydrogel.　　According to the usage cycle, contact lenses can be divided into two types: long cycle and short cycle. Traditional lenses have a relatively long usage cycle, such as annual or semi annual lenses, while short cycles include daily or monthly lenses. The shorter the usage cycle, the less protein precipitation may accumulate, making it healthier. If possible, the editor suggests choosing short cycle contact lenses. Daily disposable contact lenses, also known as disposable contact lenses, are currently a safe and healthy type of contact lens.　　According to the moisture content, 30% -50% are low moisture contact lenses, 50% -60% are medium moisture, and over 60% are high moisture. The higher the water content of contact lenses, the higher the moisture content of the lenses, making them more comfortable to wear. However, its disadvantage is that the evaporation rate of water is faster, which can easily cause dryness in the eyes, making it unsuitable for people with dry eyes.

Basic issues with contact lenses

　　Today, I will talk to you about the selection of contact lenses for beginners. It is mainly based on my own experience and the advice of ophthalmologists. If there is anything wrong, I welcome myopic patients and contact experts to supplement and correct it.　　First of all, you need to do an examination　　Although the examination can be troublesome, if you are planning to wear an invisible baby, it is really necessary to go to a regular hospital for a check-up.　　Eye condition examination　　The doctor will comprehensively evaluate whether the condition of your eyes is suitable for wearing invisible lenses.　　For example, long-term conjunctivitis, glaucoma, diabetes, dry eye, etc. may suggest you not to wear stealth. Although regretful, do not sacrifice your health at the cost. Also, it is better to wear a frame if you are too young (primary and secondary school students).　　Optometry　　Next, you need to undergo optometry. Generally speaking, there is a difference between the degree of the same person's framework and the degree of invisibility.　　And invisibility generally does not have astigmatism, so for babies with high astigmatism, customization may be very troublesome. After the test, you can ask a doctor to measure the condition of the base arc for you.　　Important indicators of contact lenses:　　Those familiar with invisibility know that there are several very important indicators that directly determine whether you are comfortable and suitable to wear this invisibility. Doctors can help you measure indicators such as basal arc, while others are based on your own needs.　　Base arc　　This indicator is very important. It refers to the curvature radius of the surface behind the lens. Speaking of people, it means the flatness of contact lenses.　　The larger the base arc, the flatter the inside of the lens; The smaller the base arc, the greater the curvature inside the lens. So if it's too loose, it will slide, and if it's too tight, it will make the eyeballs feel tired from being caught. But the base arc does not necessarily mean a perfect match. Generally, a difference of 0.1 is not a big problem. For example, some people have an 8.6 base arc, and wearing an 8.7 invisibility is also okay. (I would rather be slightly larger by 0.1, but having smaller eyes can be tiring.) But I have also bought 8.4 and 8.8 base arcs at a young age, one slide and one tight eye　　Moisture content　　The moisture content of contact lenses refers to the proportion of water in the lens.　　The higher the moisture content, the more water is needed for this invisible product. Generally speaking, the higher the moisture content of the same material, the better its oxygen permeability, but try to avoid wearing invisible materials with high moisture content.　　The reason is that if worn for a long time, the lens will lose some moisture, so you will use your tears to replenish and maintain its moisture content. Soon my eyes felt uncomfortable.　　Oxygen permeability　　As the name suggests, oxygen permeability refers to the degree to which oxygen can pass through the lens. Lenses with high oxygen permeability can fully ensure the "breathing" of the eyes. Generally speaking, the higher the water content, the higher the oxygen permeability.　　But there is no relationship between the two. Because the oxygen permeability is also closely related to the lens material and center thickness. Some good materials can break the law that "high oxygen permeability and low water content cannot coexist", such as silicon hydrogel materials.　　Center thickness and diameter　　The thinner the center thickness, the higher the comfort, enhancing oxygen permeability.　　The diameter actually determines the size of the lens, and if it is not suitable, it can cause a foreign object sensation in the eyes. Generally, 14mm is more suitable.　　How to choose annual, semi annual, monthly, or daily selling?　　Basically, we distinguish invisibility based on its duration. Long term abandonment of lenses (more than three months) and short-term abandonment of lenses (less than three months), the four types mentioned in the question are relatively common, but later what seasonal or bi weekly abandonment appeared.　　The summary is as follows:　　Beginners are advised to choose monthly or semi annual throwing, as daily throwing is too soft and inexperienced, making it easy for beginners to not fit in. After becoming proficient, one can choose to sell on a bi weekly or daily basis;　　My personal suggestion is to throw it away in Kaifeng every 4-5 months and every 8-10 months. You don't have to wait for the expiration date, because even if you take good care of it, the lenses that are nearing expiration may have attached a lot of protein or even deformed. Will make the eyes uncomfortable;　　Be sure to pay attention to hygiene. Except for daily lenses, all other lenses need to be rubbed with care solution in the palm of the hand, then lifted and rinsed with care solution for 5 seconds. Nursing solution should not be expired or reused.　　Both daily and monthly selling are relatively expensive. Anyway, wearing invisibility is a dead end. For the sake of health and hygiene, it is advisable to choose short cycle disposable lenses as much as possible after adaptation.