That is a hard contact lens, also called an OK lens.
Orthokeratology lens, also called an OK lens, is a new type of myopia correction method. Since the introduction of OK mirrors in our country in 1998, it has attracted quite a lot of attention. Only by correctly understanding OK mirrors and eliminating misunderstandings can this technology better serve mankind.
1. Can OK lenses cure myopia? OK lens uses the shape of the lens to quantitatively correct the curvature of the cornea, thereby temporarily reducing the degree of myopia of the eye. Generally, good vision can be maintained throughout the day after being worn overnight. People with myopia can get good distance vision without wearing glasses, which is the charm of OK Talk. However, if you stop wearing glasses, your eyes will slowly return to their original myopia degree. Under the current technical conditions, any claim that OK lenses can cure myopia or permanently reduce myopia is misleading.
2. How much lower can the OK lens reduce? This depends on the conditions of wearing the eye, including the curvature of the cornea, corneal eccentricity and axial length of the eye. If the wearing conditions are good, it is normal for the temperature to drop by 500-600 degrees, or even more.
3. Should OK glasses be worn at night or during the day? A few years ago, because the oxygen permeability of the lens material was insufficient, OK lenses could only be worn during the day. Facts have proved that due to constant blinking during the day and poor lens positioning, the correction effect of myopia is very unsatisfactory. Since the advent of highly oxygen-permeable materials (oxygen permeability coefficient greater than 120), OK lenses have been changed to be worn at night. Not only is the lens positioning stable, but the eyelids exert a certain pressure on the lens, and sufficient negative pressure is generated under the lens to achieve corneal shaping. A critical success.
4. Has it been approved by the US FDA? The U.S. Food and Drug Administration (FDA) never approves any medical treatment, only the effectiveness and safety of specific lenses or lens materials. The U.S. FDA has approved and registered a variety of OK lens materials that can be worn overnight, and has currently approved individual high-quality OK lenses for clinical verification.
5. How to wear regular OK glasses? OK glasses should be fitted by a registered optometrist or physician. During the wearing process, at least computer optometry, corneal curvature testing, comprehensive optometre testing, slit lamp microscopy testing, intraocular pressure testing, fundus examination and corneal topography examination are required. Therefore, if wearers of OK glasses find that the fitting unit does not have the above-mentioned inspection methods and the price of the lenses is very low, they should not rush to get glasses.
6. How to use the OK mirror correctly? 1． Within 3 months of wearing OK glasses for the first time, you must go to the optician's office for formal and comprehensive review at the prescribed time, at least 5 times. After wearing glasses for 3 months, regular reviews are still required. 2. While wearing glasses, you must maintain personal hygiene and wash your hands when handling the lenses. 3. When wearing the lenses, be sure to fill the inside of the lenses with eye moisturizing liquid before wearing the lenses. After wearing the lenses, be careful that there are no air bubbles under the lenses. 4． If redness or eye pain occurs accidentally while wearing glasses, don't be too nervous. You can stop wearing them for two or three days or ask a doctor to review and adjust the lens specifications.
Using OK lenses to treat myopia should be done with caution
Wang Fangrun, Department of Ophthalmology, Jinshan Hospital, Shanghai Medical University
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In the past year, many domestic ophthalmology medical units have introduced OK lens technology to treat myopia through different channels. Because of its own characteristics and my country's special social conditions, some areas are emerging. In this regard, it is necessary to conduct in-depth analysis and discussion on its role and significance.
The role of OK (orthokeratology) lenses in treating myopia is limited to wearing special hard contact lenses to shape the cornea, increase the radius of corneal curvature, and reduce the refractive power of the cornea, thereby reducing the diopter of myopia. , improve distance vision, so it is also called "orthokeratology". Clinical observation results of OK lens in treating myopia have initially shown that within a certain range, the treatment effect is obvious and rapid, and because of its non-surgical operation and reversible treatment effect, OK lens has become one of the current methods for correcting the diopter of myopia. However, the recent effectiveness of OK lens is only a superficial phenomenon and can sometimes cause misunderstanding. After more than a year of practice, people’s understanding of the treatment of myopia with OK lenses has become more calm and objective.
OK lenses have limited effect in reducing the diopter of myopia, and are mainly suitable for people with ≤-3 D. Changing the optical conditions of the cornea only serves as a symptomatic treatment (lowering the diopter), but cannot change the pathological process of myopia. Due to possible problems in lens design, production and wearing, as well as individual differences, the actual treatment effect varies from person to person and from time to time. It is difficult to make a random judgment based on existing experience. The therapeutic effect of OK lens is reversible and highly volatile. If you want a stable effect, you must wear glasses intermittently (some patients often reduce treatment compliance because of this). The treatment course of OK mirror is long, the follow-up is difficult, and the workload will continue to accumulate and expand like a snowball. Although OK lens technology has possible development prospects, there are many unknowns, such as the technical details in lens design and production, the ratio of the four arc diameters, the relationship between the curvature size and corneal morphology and refractive power, etc. There is no clear introduction in the data. . If we only rely on existing clinical data to evaluate OK lens technology, we still need comprehensive and in-depth observation and analysis to understand and grasp its regularity. There is a lack of effective and convincing explanations for the anomalies that sometimes occur. At the same time, it is difficult to estimate and judge which of the abnormal phenomena are inevitable, which are accidental, what are the regularities, the frequency and extent of abnormal phenomena, and the relationship between various factors. If you want to ensure the technical effects of OK lens treatment, the links and processes should include lens design, production and application. However, analyzing only one of them is one-sided.
The lens prescription can now be simplified to only the corneal curvature record, plus the subjective lens insertion power. Lenses are even sold as disposable items, regardless of their quality and effectiveness. However, the "personality" of OK lens technology far exceeds the "university". With different individuals, there are great differences in the effects and reactions during use, making the final treatment results difficult to control and master. Although distance vision can be improved after using OK lens treatment, it is difficult to determine whether the vision quality and other visual functions will be affected. Therefore, it is not possible to formulate a comprehensive and effective clinical treatment routine suitable for each individual.
The side effects of OK lenses in treating myopia are the issue that people are most concerned about. Generally speaking, the conditions are basically the same as those that may occur with other rigid contact lenses. However, the OK lens is a special design for treatment purposes, that is, the lens has a molding effect (part of it is close to the cornea), so its short-term and long-term effects may cause acute and chronic injuries and pathological changes in function and structure. should be ignored. It is known that many abnormal phenomena, such as double images, increased astigmatism, central islands and indentations in the cornea, can be related to a variety of reasons (mainly lens deviation from the center). At present, it is difficult to avoid abnormal phenomena by improving the design, production and application of lenses.
There are many issues worthy of discussion and analysis. Except for the effect that "OK lenses can effectively prevent the development of myopia", there is no strong evidence to confirm the role of astigmatism and the dynamic changes in astigmatism that occur during the treatment process. In addition to the unclear characteristics, rules and solutions, there are still many issues to be discussed. For example, is the design of the OK lens with fast action and corrective amount in one step (the therapeutic lens and the maintenance lens are the same lens) reasonable? With the development of technology, will this be necessary in the future? What is the role and necessity of trial lenses? Is it possible? Promotion? Are the current lens design parameters and production methods equally suitable for the anatomical and physiological characteristics of the corneas of yellow and white races? The efficacy of wearing glasses at night (whether eyelid tension has any effect), side effects (effect on oxygen exchange and metabolism of other substances) and daily What is the difference between wearing glasses? What are the differences in production, function and application between the two? What are the symptoms and signs (visual acuity and diopter, astigmatism detected by different methods, etc.) that appear during the treatment process that are out of sync or What rules can be found for contradictory phenomena? How to explain this exactly? What are the effects of lenses that are too tight and too loose and how to deal with them, especially when you do not have the conditions to change lenses at will? How to solve it? It can adapt to different patients to consolidate and What other methods can be used to maintain the effect? ??Foreign lens manufacturers only need the Chinese application market to provide simple eye examination parameters. Based on this alone, can high-quality lens design and production be guaranteed? Is the simplification of the design and production of OK mirrors an actual need, or is it for the convenience of promotion? Is the design and promotion of the "lens library" also caused by this?
Although a large number of OK mirror businesses have been carried out in our country, but Since foreign countries only supply lens materials and do not provide technical information, they are limited to applications and cannot comprehensively understand and effectively compare their technologies, thus limiting our in-depth understanding of them.
From a long-term perspective, this is a problem that needs to be solved. Maybe some problems are not difficult to solve, but there are definitely other or new problems that may be discovered that cannot be solved by existing knowledge and inspection methods. As for the long-term effects, it is unknown. All the above indicate the immaturity of OK mirrors in terms of materials, design, production and application. It is not difficult to understand why the U.S. Food and Drug Administration, although it has approved individual materials for orthokeratology, still has reservations about it. For example, the notice on September 25, 1998 warned professionals and their users to be cautious and not to use blindly (such as emphasizing that lenses are only for daily wear), requiring close follow-up and timely reporting of problems if found. In addition, people with myopia who receive treatment for certain special purposes (such as passing physical examinations) continue to enter society, engage in jobs that were previously restricted, or even be entrusted with important tasks. Due to possible instability of vision (including near vision) and other imperfections in visual function, which bring about some corresponding medical ethics issues. Should we pay attention to this under certain circumstances? The treatment of myopia is an important topic that meets the needs of medicine and society. Treat any new When exploring, one should neither blindly deny nor easily affirm. Due to the active participation of some businesses, which has promoted the development of OK glasses in various places, coupled with the attraction of obvious short-term effects, as well as the blind demand for distance vision in society and other factors, it is estimated that OK glasses may become popular in our country. This creates a passive environment for professional workers and administrative departments. At present, the commercial behavior of OK glasses is far ahead of academic research (such as the emergence of many brands and promotion methods in a short period of time, with various prices and obvious irrationality). We should be vigilant about this and not repeat the same mistakes (blindly introducing and promoting myopia). work passivity and adverse consequences caused by therapy). In view of this, ophthalmologists should, on the basis of further mastering information and in-depth observation, set up application and research sites respectively according to the principles of prudentness and standardization as appropriate, carry out special collaboration, and organize the demonstration and confirmation of the role and scope of application of OK lenses. . The subjects to be treated should currently be limited to the best adapted conditions (such as myopic anisometropia, etc. can be listed as the first choice. Some young patients who are eager to be treated may wish to try OK lenses first if they plan to undergo surgery). When receiving patients, you should not be vague and make random promises such as "taking off and wearing glasses". During the long-term treatment process, the significance of "functional vision" must be emphasized, and patients must be taught how to protect themselves seriously and responsibly.
The key to the technical work of OK lens is not the initial operation and prescription, but the follow-up observation during the entire treatment process and the specific design and correction of the lens. In fact, ideally wearing OK glasses is an art in itself. OK lenses are not simply commodities, and their use to treat myopia should be considered a medical practice. The inspection must be accurate, the operation must be standardized, and a prescription must be issued by a qualified professional before it can be prepared (for the lenses used, the provider should introduce the various properties, characteristics, and sources of the material in detail, and make various commitments for beneficial application and promotion) , and personally observe, ensure follow-up, and directly participate in the entire treatment process. Units that have no professional foundation or lack basic conditions (including routine optometry equipment and corneal topography, etc.) should not act blindly. Administrative departments must intervene reasonably and manage effectively. The news media must conduct scientific propaganda and provide correct guidance.
In short, OK scope has been used in clinical practice for a short time and has not yet been systematically summarized. There are many issues that need attention, including effect analysis, side effect observation and methodological discussion. With the selection of OK mirror production materials and improvements in technology, as well as active modifications and innovations in design and application, and with continuous efforts from all aspects, OK mirror technology will be able to continue to develop and improve, and strive to be selectively and formally applied in clinical practice.