Abstract: once children and adolescents develop high myopia, the length of ocular axis has exceeded 10% of normal eyes. With the growth and development and increasingly heavy learning tasks, the ocular axis will further elongate and the degree of myopia will continue to increase, which may lead to various retinopathy, serious damage to visual function and even the risk of blindness in these children, thus affecting life planning.
the prevalence of juvenile myopia in China ranks first in the world, and the prevalence of high myopia (myopia diopter I > 6.00D) is also rising. For example, a survey in Guangzhou in 2003 showed that the prevalence of high myopia among 15-year-old people has increased from less than 1.5% to 4.8%; It is also reported that the prevalence of high myopia among 18-year-old students in Taiwan has increased significantly from 9.2% in 1986 to 2L% in 2000; Some scholars reported that the prevalence of myopia among adolescents aged about 15 in China was as high as 78.4%, while the survey results of the prevalence of myopia in a larger sample showed that the proportion of high myopia accounted for 19.5%.
in terms of etiology, high myopia should be the result of the joint action of genetic factors and environmental factors. How to prevent and control the occurrence and development of high myopia has become a hot spot in the field of optometry.
I. should keratoplasty be performed? Children and adolescents with high myopia in the
families generally have early onset and rapid progress of myopia, while parents have stronger awareness and more urgent requirements for the prevention and control of children’s myopia, and often have taken a variety of corrective treatment measures early, such as wearing single focus Bifocal or gradient multifocal frame glasses, acupuncture, massage and traditional Chinese medicine treatment, the use of various so-called instruments and equipment for the prevention and treatment of myopia, eye exercises and various training, but most patients can not prevent the annual increase of myopia diopter by more than 1.00d. When it is found that many methods are basically ineffective, compared with surgical methods, most parents place more hope on corneal plastic surgery. Once children and adolescents with
develop high myopia, the length of ocular axis has exceeded 10% of that of normal eyes. With the growth and development and increasingly heavy learning tasks, the ocular axis will further elongate and the degree of myopia will continue to increase, which may lead to various retinopathy, serious damage to visual function and even the risk of blindness in these children, thus affecting life planning. For these children, actively taking all feasible means to slow down the development of myopia as much as possible should be an important issue in the field of optometry. Corneal plastic surgery is the most promising method of optical correction, so we think it is necessary to wear corneal plastic lens for correction as soon as possible.
2. Can corneal plastic surgery be performed
in recent years, with the development of corneal plastic technology, especially the close cooperation between lens design and high-precision NC machining, the clinical application scope of corneal plastic surgery has been greatly expanded. In order to maintain the stability of daytime visual effect, the adaptive range of the best myopia diopter should not exceed 5.00d, which is limited to patients with medium and low myopia. Some high-end fitting institutions and experienced fitting doctors have explored some fitting technologies for the treatment of high myopia ametropia through continuous research and good. It is reported abroad that for patients with myopia diopter of 6.00 ~ 10.00d, the newly designed corneal shaping lens can make the naked visual acuity reach 1.0 without keratoconjunctival complications above grade 2; Compared with frame glasses, the slowing effect of axial growth in moderate and high myopia after keratoplasty can reach 63% in 2 years. The corneal shaping lens designed for the curved surface of high corneal astigmatism ring has also achieved successful experience at home and abroad in promoting shaping effect and improving visual quality, and the effect of slowing down the growth of ocular axis can reach 52%.
summarize the current clinical experience. For patients with high myopia over 6.00D, compared with the use of frame glasses, after fitting corneal plastic lens, in addition to reducing the diopter and improving the naked vision, it does significantly slow down the development speed of myopia. After some patients insisted on wearing corneal shaping glasses for 2 ~ 4 years, the myopia diopter did not increase, and the change of ocular axis decreased significantly. In addition, some patients with amblyopia caused by high myopia, astigmatism or high anisometropia wear frame glasses to correct vision less than 0.6, and the covering and amblyopia training are invalid. After wearing corneal shaping glasses for a short time, the vision can be quickly improved to normal. The mechanism of these clinical effects needs to be further discussed.
III. how to perform corneal plastic surgery
for high myopia, the fitting of corneal plastic lens is very difficult and difficult to succeed. Those with clinical corneal astigmatism over 2.00d are often complicated with high myopia, which aggravates the complexity of fitting, reduces the success rate and increases the risk of keratoconjunctival complications. Therefore, in the early stage of corneal plastic surgery, we should not rush to receive patients with high refractive error. It is best to start with patients with the best indications, obtain hundreds of successful experiences and consider the challenges after systematic training. Although Beijing Beiyi optometry Research Center has more than ten years of experience in fitting corneal shaping lenses, it still can not boast that it has achieved 100% success. It still needs to continue to learn and explore and pursue higher professional skills.
compared with frame glasses, the higher the diopter of corneal contact lens, the better the imaging quality. As for how to select the type of contact lens, it needs to be comprehensively considered according to the specific situation of the eye and the needs of all aspects, and adjusted at any time. It is found that the myopia control effect of some patients with high myopia wearing rigid gas permeable contact lenses (RGPCL) is not good. After replacing the corneal shaping lens, a good effect of stably reducing the diopter of myopia and controlling the development of myopia can be obtained. However, not all patients with high myopia should choose corneal shaping lens first. The choice should also be determined according to whether the patient has high astigmatism, corneal K value, anisometropia, other eye conditions, difficulty of fitting and acceptance, adaptability and eye reaction after trying on the lens, patients’ conscious symptoms, etc. Some patients wear corneal shaping lenses for 1 ~ 2 weeks at the initial stage, although the visual effect is satisfactory, but due to repeated adverse reactions such as corneal spotting and insufficient comfortInstead of corneal plastic lens, it was replaced with RGPCL.
can learn from the methods of selecting and wearing various intraocular contact lenses:
(1) for high myopia with no more than 8.00d, the degree of compliance astigmatism is no more than 1.25d, there is no abnormality in the external eye, and the corneal radian, diameter and other parameters are in the normal and appropriate range, the method of wearing corneal shaping lenses at night can be considered, The diopter of myopia can be designed as 4.00 ~ 6.00D. If the corneal astigmatism exceeds 1.50D, the ring curved surface design is adopted. It depends on whether the daytime naked eye vision meets the standard and is stable. Sometimes it can be further improved with low-power frame glasses. If you can keep the external eye healthy, you can consider continuous use. At present, many successful cases have been reported at home and abroad.
(2) for ultra-high myopia above 8.00d, in order to maintain relatively stable visual effect and safety, it is recommended to wear the corneal shaping lens on a daily basis or elastic wear based on daily wear. Due to the higher requirements for vision and binocular vision when wearing glasses during the day, a comprehensive optometer should be used to comprehensively detect the refractive state and binocular vision of naked eyes and wearing glasses, so as to determine the additional refractive power. At the same time, it is necessary to maintain the appropriate activity of the lens and good tear circulation.
(3) for ultra-high myopia, astigmatism above 3.00d or irregular astigmatism, optometry RGPCL should be selected first. If it can significantly improve the visual quality and function, and has a good mitigation effect on the development of myopia, it can be used continuously; If the control effect of myopia development is poor, replace it with corneal shaping lens after the corneal astigmatism is reduced and more regular.
(4) for patients with high anisometropia, the combined application of one corneal plastic lens and the other RGPCL can be considered. If amblyopia exists at the same time, it is urgent to improve visual acuity. It is necessary to take the daily wearing method of corneal shaping lens, combined with cover therapy and amblyopia training. After the visual acuity returns to normal and stable, it can be replaced by night wearing corneal shaping glasses to gradually reduce the degree of anisometropia and slow down the development of myopia.
IV. how to evaluate corneal plastic surgery
corneal plastic surgery is characterized by improving visual quality and overall visual function. The corneal plastic effect is obvious. After wearing glasses during sleep time, part of the diopter can be reduced during the day, the naked vision can be improved to varying degrees, and the effect of controlling the development of myopia is obvious. Promoting myopic defocus in the middle peripheral region is the research focus to control the development of myopia. At present, the best way to obtain this exact effect is keratoplasty; In addition, keratoplasty can significantly reduce the adjustment lag and improve the adjustment sensitivity and amplitude, which is also an important factor in controlling myopia. At present, the main parameters to evaluate the therapeutic effect of keratoplasty are the change value of diopter and ocular axis. Although the domestic and foreign literature reports using strict simultaneous control research are basically aimed at patients with medium and low myopia, some scholars consider the improvement of defocus in the middle peripheral region of retina. The higher the diopter of myopia corrected by keratoplasty, the more obvious the tendency of myopic defocus, It is considered that the control effect of keratoplasty on medium and high myopia should be better, and the efficiency of slowing down the growth of ocular axis should be more obvious. At the academic conference of the American Society of corneal plastic surgery in April 2014, some scholars reported the changes of ocular axis after wearing corneal plastic lenses for 5 years in different myopia diopter arrays. The growth of ocular axis in 1.00d group (n = 45) and 2.00d group (n = 72) were 1.95mm and 1.20MM respectively, 3.00d group (n = 50) and 4.00d group (n = 47) were 0.25mm and 0.35mm respectively, while that in 5.00d (n = 36) group and 6.00D (n = 46) group were only 0.15mill and 0.05inn respectively, This result confirms the view that the higher the diopter of myopia, the more significant the effect of keratoplasty. Of course, this effect is related to the special design of keratoplasty for high myopia.
are used in patients with high myopia and astigmatism. When using keratoplasty, in addition to paying attention to the changes of myopia diopter, astigmatism and axial length, we should also pay attention to the follow-up observation of the overall corneal morphology (corneal topography) and ocular surface health, such as corneal thickness, the number and morphology of corneal endothelial cells, corneal biomechanical properties, intraocular pressure and fundus, To further evaluate the efficacy and safety of treatment. Naked vision, corrected vision, contrast vision, wavefront aberration, stereopsis and other indicators related to visual quality and visual function must be recorded, so as to ensure the sustainable treatment of stability and improvement as far as possible. Therefore, it is emphasized again that only under the condition of good medical environment and conditions, led by professional optometrists with rich experience and design ability, and with the close cooperation of professional teams, can it be possible to carry out the highly skilled work of corneal plastic surgery in the treatment of high myopia and astigmatism.
with the increasing prevalence of high myopia and astigmatism, clinical studies have confirmed that the most effective optical correction methods and myopia control methods should be taken in time for children and adolescents. That is, corneal plastic surgery is very necessary and feasible. Scientific and rigorous fitting process, use guidance and flexible and diverse operation methods can ensure high effectiveness and safety of keratoplasty. However, the matching doctor must have rich experience and a high sense of responsibility. Have the technical level of excellence; Attention should be paid to the overall visual development of patients during fitting; The risks of wearing glasses overnight and improper nursing should not be ignored, and its standardization and safety should be closely monitored. In the future, we need to continue to explore in practice and carry out more in-depth and lasting clinical observation and research, so as to further confirm and improve the understanding of corneal plastic surgery in the treatment of ametropia, including high myopia and astigmatism.