The annual wearing cost is tens of thousands of yuan. Are OK glasses a “magic weapon” to prevent myopia?

The reputation of the "magic" anti-myopia "OK" glasses, which can be worn at night and taken off during the day, is mixed. What is the principle of OK glasses? Is it really that magical? Why are they so expensive?

Written by reporter Zhao Ling, Photo and text editor Chen Yongjie

New Media Editor/Li Yunfeng

Interview experts

Song Hongxin (Deputy Director and Chief Physician, Ophthalmology and Optometry Center, Beijing Tongren Hospital)

Before the new semester started at the end of February, CCTV reporters found that it was hard to get an appointment for the OK lenses in the ophthalmology clinic of Beijing Tongren Hospital. The description of "wearing glasses at night and taking them off during the day" makes people curious. What are the effects of OK lenses? Are they really OK for everyone? What is the controversy about them? Why are there so many descriptions of OK lenses "ruining lives" on a certain search engine?

▲OK lenses have a certain effect on preventing myopia

(Photo source/gintereyecarecenter.com)

▪ ▪ ▪

Can prevent myopia in sleep

The "OK" in "OK lenses" does not mean "good", but the abbreviation of OrthoKeratology. The medical name is "orthokeratology". It temporarily reshapes the surface of the cornea through physical principles, so that light enters the eye and forms an image before the retina (myopic defocus), thereby controlling the rapid development of myopia. Before understanding the working principle of orthokeratology lenses, we must first know how myopia is formed.

The human eye is like an advanced camera. When parallel light from the outside world enters the eye and is formed on the film (retina) through the camera lens (cornea), a clear image will be formed. Myopia means that when parallel light from a distance enters the eye, the focus no longer falls on the film, but can only converge in front of the retina, resulting in a blurred projection on the retina. Myopia can be divided into two types, one is refractive myopia (the curvature of the cornea or lens is too large), and the other is axial myopia (the front-to-back diameter of the eye becomes longer).

▲The principle of myopia (Photo source: Science Popularization China)

Among them, the most common myopia in clinical practice is axial myopia, which refers to myopia caused by the elongation of the eye axis. "The eye axis is simply the distance between the eye camera lens and the film, that is, the length of the eyeball, which will become longer with the growth and development process. When the eye axis grows, the curvature of the cornea and lens is within the normal range, and the focus of the image is in front of the retina, axial myopia is formed." Song Hongxin, deputy director and chief physician of the Ophthalmology Optometry Center of Beijing Tongren Hospital, introduced.

Theoretically, the process of eye axis lengthening is irreversible. "Whether it is frame glasses, OK lenses, or myopia surgery, they all change the refractive state of the eye so that the objects received by the human eye can be clearly imaged on the retina," said Song Hongxin.

As a kind of rigid gas permeable corneal contact lens, OK lens is generally worn at night, and is worn for 8 to 10 hours when sleeping. It is taken off after getting up in the morning, and you can have clear naked eye vision all day long. Some advertisements simply and crudely say that "OK lens can flatten the corneal curvature", but Song Hongxin said that it is not achieved by "pressing", otherwise myopia will rebound soon after taking off the lens in the morning, and it is impossible to maintain clear vision all day long.

It turns out that there is a layer of epithelial tissue on the surface of the cornea, which, like the epithelium on the surface of the skin, will continue to regenerate and renew. What OK lenses want to do is to rearrange the corneal epithelial cells through the physical effects of negative pressure suction and positive pressure compression, flatten the curvature of the front surface of the central cornea, and steepen the peripheral cornea. In this way, the light passing through the center of the cornea is imaged on the retina, temporarily reducing the myopic refractive power and improving naked eye vision. Because the peripheral cornea becomes steeper, the light around the cornea can be imaged in front of the retina (myopic defocus), and the eye receives a signal that the "eye axis does not grow". This mechanism can control the growth of the eye axis and slow down the rapid development of myopia. "For example, myopia that originally increased by 100 degrees a year may only increase by 30 degrees after wearing it," said Song Hongxin.

▲Principles of wearing OK glasses (Photo source: Science Popularization China)

Many people are worried about whether long-term wearing of OK lenses will damage the cornea, or whether myopia will rebound significantly after removing the lenses. Song Hongxin also gave everyone a reassurance: "First, there is a layer of tear protection between our orthokeratology lenses and the cornea. If the parameters of the orthokeratology lenses are appropriate, the safety of wearing the lenses is still very high. Secondly, the corneal epithelium has the function of self-repair. It will generally be replaced naturally once every 24 hours, and there will be a major renewal every 7 days. Therefore, if the corneal epithelium is damaged, as long as it is handled promptly and correctly, the cornea will be repaired quickly. Because orthokeratology lenses control the development of myopia through physical principles, after stopping wearing OK lenses, the corneal epithelial cells will be redistributed evenly and restored to the corneal shape before wearing the lenses, and there will be no retaliatory rebound."

▪ ▪ ▪

Reputation has been like a roller coaster for 20 years

There was a time when there was a lot of negative news about OK lenses, and cases of "OK lenses ruining a life" were heard everywhere. In fact, there was a time difference between them.

As early as around 1998, OK lenses were introduced into my country and quickly became popular across the country. They can be seen in every regular hospital and every individual ophthalmology clinic.

However, around 2000, cases of corneal damage, ulceration, and even near blindness caused by wearing OK lenses appeared in many provinces and cities across the country, and the resulting lawsuits have been pending for many years. With doubts and criticism, OK lenses disappeared for a time.

In 2010, an ophthalmologist said in an interview that doctors prefer to call this technology "orthokeratology lenses". "This is not out of concealment, but because we are afraid of misunderstanding by patients. After all, OK lenses had a bad reputation at the time."

In 2022, the department that fits orthokeratology lenses has once again become popular. When interviewed by CCTV, patients said, "It's not easy to get an appointment, and it took about two or three weeks."

Why has the reputation of OK lenses experienced ups and downs like a roller coaster over the past 20 years?

"It's not the problem of the OK lens itself, there are too many external factors," said Song Hongxin. The domestic OK lens market was very chaotic at that time. On the one hand, OK lens products were copied in large quantities and could even be bought in street shops. A large number of institutions and individuals without medical qualifications participated in the market. On the other hand, consumers did not follow the standard methods to care for the lenses and did not meet the requirements of disinfection and antibacterial.

Song Hongxin said: "At that time, many people sold OK lenses as ordinary commodities and ignored their medical properties, which led to some tragedies."

While the OK lens disappeared in China, the orthokeratology lens in Europe, America, Japan and other regions thrived with strict medical supervision and good myopia control effect. In 2005, after in-depth exchanges with foreign counterparts, Chinese ophthalmologists gradually realized the charm of orthokeratology lens and reintroduced it to China.

This time, for the sake of safe application, orthokeratology lenses have been given the "high-end" identity of Class III (the highest category) medical devices, and have strict fitting specifications: that is, they must be fitted in a regular medical institution, under the guidance of an ophthalmologist, by a strictly trained optometrist.

Moreover, this return makes it clear that orthokeratology is not a panacea and is by no means OK for everyone. It has strict indications: it is generally recommended for people over 8 years old, with myopia below 600 degrees, astigmatism below 400 degrees, normal corneal morphology, and no organic ophthalmic lesions. OK lenses need to be individually fitted and "customized to the eye". After wearing them, you should have regular checkups according to the doctor's advice and maintain good hygiene habits. It is generally recommended to replace the lenses once a year to a year and a half.

Song Hongxin said that although OK lenses can indeed slow down the rapid development of myopia, the procedure for wearing and removing them is relatively complicated, and the cleaning process also requires relatively high sanitary conditions. It is not recommended for relatively young children with poor cooperation or children with low myopia and slow myopia growth. For people who already wear orthokeratology lenses, care is very important. They must use regular care products for care and rinse the lenses with physiological saline instead of using domestic water to contact the lenses, so as to ensure that no microbial pathogens come into contact with the eyes.

▪ ▪ ▪

Why are OK lenses so expensive?

For children and parents, wearing OK lenses is a gradual process of becoming proficient.

Mrs. Toothpick is a mother whose daughter Xiaohei has been wearing OK glasses for 15 months. After hurting her child once, she felt like she was in a battle with glasses every day. Fortunately, she is now able to wear them skillfully.

In fact, these troubles are only after wearing them. For a wider group of people, the price of OK lenses is the biggest "stumbling block". At present, the price of OK lenses is generally between 7,000 yuan and 12,000 yuan, and they need to be replaced every one to one and a half years. Daily care solutions and eye drops are also expensive. Someone did some calculations and said that it basically costs about 20,000 yuan a year.

The reason why the price remains high is mainly because the domestic OK lens market has long been monopolized by foreign brands, and the materials of domestic brands are all imported from abroad. The high cost of imported production equipment and the experimental approval of Class III medical device-related certificates have jointly led to higher sales prices.

Although OK glasses are expensive, parents still pay for them, and they spare no effort for their children's eyesight. Just like Mrs. Toothpick said: "After school, other people ask their children 'Did you have a good day?' When I pick up Xiao Hei, I ask 'Do you often go out of the classroom to look into the distance?' If the answer is no, I will be depressed for the whole day." In this regard, Song Hongxin suggested: "Myopia prevention is more important than treatment. Looking into the distance more often and doing outdoor sports are of great benefit, but we must also keep a calm mind and do not become a burden in the hearts of parents and children."

Produced by: Science Central Kitchen

Produced by: Beijing Science and Technology News | Beijing Science and Technology Media

Welcome to share to your circle of friends

Reproduction without authorization is prohibited