On March 22, we did an issue on solutions for correcting vision and had mentioned OK lenses. After the publication of the newspaper, many readers asked questions about OK lenses through Weibo and WeChat of the weekly newspaper. What kind of people are suitable for wearing OK lenses? In this issue, we have invited ophthalmologist Chen Yan to help you learn more about OK lenses and answer your most important questions. Let’s take a look. Orthokeratology (Ortho-k), also known as OK lenses, is a method of temporarily and reversibly reducing myopia, improving naked eye vision, and delaying the development of myopia to a certain extent by changing the shape of the cornea through specially designed lenses. OK lenses are generally used for children or adolescents over the age of 8 who are experiencing rapid myopia growth, and can also be worn by adults who have a need for lens removal or naked eye vision. The ability to wear OK lenses depends on eye parameters, refractive error, cooperation and compliance with follow-up visits, and the speed of myopia progression. A detailed examination by an experienced ophthalmologist at a regular hospital is required to confirm the suitability of OK lenses. Unlike general contact lenses, OK lenses are worn at night and can guarantee clear vision during the day without glasses. This is because OK lenses are a special reversed geometric design that reshapes the cornea through the direct pressure of the lens, the mechanical massage of the eyelids and the hydraulic principle of tears, flattening the central zone and thickening the paracentral zone, so that vision can generally be maintained for a full day after removal. The degree of flattening is precisely designed to match the degree of myopia. After lens removal, the naked eye vision is basically the same as before with glasses. However, because the cornea has a memory, the flattened form will slowly recover over time, so if you want to maintain continuous clear vision, you must insist on wearing them at night. Special reminder: Corneal shaping lens is a Class III medical device, a medical tool for ophthalmologists to implement myopia correction, customized by ophthalmologist prescription, under the guidance of ophthalmologist standardized use and must follow medical advice, close follow-up. Hum Age: 10 years old Wearing time: half a month Hum is a 10-year-old boy, myopia 125 degrees last year, the first check at the beginning of the year, the degree has deepened to 375 degrees, the mother is very anxious, which took her son to the hospital to try a trial with OK lenses. After a detailed pre-wear examination and communication, the doctor chose the parameters of the trial piece for Hum, and after trial wear and deployment, finally determined the custom prescription for OK lenses. Hum experience: At the beginning, it felt like there was a foreign body in my eyes and it was a little itchy. After wearing it for one night, I got used to it. The first day or two, my eyes did not recover quickly and I still needed to wear a frame during the day. After that, I could see much more clearly and didn’t need to wear rimmed glasses. The mother said: At first, she was worried that wearing OK lenses would affect her cornea and that the child would be too young to tolerate it. Later, she went to the hospital and carefully learned from the doctor about the principle of OK lenses for vision correction. After returning home, I did everything the doctor told me to do. In addition to going to the hospital for regular reviews, I also helped my son take care of his glasses every day. The boy likes to play basketball, and wearing OK lenses makes it easier for him not to wear glasses during the day. The child is also in a good mood, even teachers say he has grown handsome. Experts say: children’s myopia, congenital genetics is one aspect, and later in life may be related to eye hygiene, environment. After a week of wearing OK lenses, he came for a review and his corrected visual acuity was 1.0. What kind of people are suitable for wearing OK lenses? There are conditions for OK lenses to be used for myopia treatment: good health, no eye disease, good personal hygiene, children with some self-care ability and parental supervision, able to cooperate with contact lens wear, myopia below 600 degrees, cis-ruled astigmatism below 150 degrees, retro-ruled astigmatism below 75 degrees, myopia/astigmatism >2, corneal K value between 39.5 and 46D, etc. 46D, etc. (Corneal K value is the value of corneal curvature, which is one of the indications for wearing OK lenses.) What tests are required to wear OK lenses? The fitting of OK lenses requires a thorough examination of eye health and eye parameters, without which it is impossible to successfully complete the customization of OK lenses. A perfect fit for OK lenses should ideally include: slit lamp examination of the anterior segment, tear film examination, corneal curvature, corneal topography, medical optometry, IOP examination, corneal thickness, corneal endothelial cell count and axial length measurement. It is roughly estimated that the cost of the required instruments and equipment is more than millions. Therefore, OK lenses are not something that can be performed by random institutions, but must be performed by a professional optometrist at a regular hospital. How long can I wear a pair of OK lenses? A pair of OK lenses can generally be worn for 1-1.5 years, with the extension of time, the lens wear, aging and other conditions occur, need to be replaced regularly. If the original lenses have good and stable vision after removal and the fit is ideal, new lenses can be made according to the original lens parameters without stopping wearing them. However, if you want to know the exact refractive index, it is better to stop wearing the lenses for more than 3 weeks to allow the corneal shape to return to its original level, and then re-measure the prescription and curvature. In addition to the assessment of post-lens vision, corneal topography and intraocular pressure, a fluorescence assessment is also required to ensure a safe and healthy wearing condition. The more expensive OK lenses are, the better the results? At present, there are several brands of OK lenses in China that have the license certificate issued by SFDA, such as Mondial (Optronics/Hefei), EUCLID (Euclid/USA), Elite Vision (USA), etc. Various brands of OK lenses have different materials and designs, the oxygen permeability of the lens material, manufacturing and processing processes may also vary, all have their own advantages and disadvantages, suitable for different situations, not necessarily the more expensive the better. The actual lenses are not necessarily expensive, but they can be tried and chosen according to the specific conditions of the wearer’s eyes. Are the results of OK lenses really that amazing? OK lenses are designed to reduce the original myopia to as low or no level as possible, but theory and actual practice sometimes differ, for example, children with higher prescriptions, larger astigmatism, and deviations caused by too loose or too tight eyelid tension can cause slightly poorer daytime vision. The ultimate measure of the effect of OK lenses is not the daytime naked eye vision, but the change in the growth of the eye axis and the effect of myopia control after the child wears the lenses regularly. Therefore, parents do not have to be too concerned about whether the vision is 1.0 or 0.8. Of course, it is certainly better to achieve the best vision, and if not, it is acceptable as long as the child can maintain useful vision for class and life. In general, OK lenses can correct myopia up to 600 degrees, more than 600 degrees of myopia may remain after removal of the lenses. Doctors do not recommend pressing the cornea too tightly or too flat in order to unilaterally correct the height, which can easily lead to accidents, such as corneal hypoxia, irregular astigmatism, etc. Do OK lenses affect eye health? Many people are concerned about the safety of OK lenses. Orthokeratology lenses are contact lenses and in theory will still have the complications of contact lenses. However, as long as OK lenses are fitted correctly, scientific wear methods are strictly followed, regular reviews are conducted, and problems are seen in a timely manner, complications can be minimized, and most problems can be recovered by suspending wear. The main problems found with OK lenses are: overly broad indications, irregular fitting, untimely follow-up, and improper lens removal and care. These problems can be corrected with timely medical attention.