What are keratoplasty lenses? Orthokeratology lenses, also known as “O.K.” lenses, are “specially designed rigid contact lenses” that are made of different materials and designed differently than what we usually call “contact lenses”. It is a hard, breathable contact lens. The keratoplasty lens has a unique inverse geometric design, the central curvature of the lens is flatter than the central curvature of the individual cornea, and can be worn at night to change the curvature of the central anterior surface of the cornea, thereby temporarily reducing or even eliminating myopia. What is the principle of correcting myopia and controlling myopia progression? Corneal shaping lenses temporarily reduce myopia by changing the curvature of the anterior surface of the cornea. Compared to frame glasses, they not only correct the refractive state of the central retina, but also correct the hyperopic defocus of the peripheral retina, thus effectively controlling the excessive growth of the eye axis in children. In recent years, several research results at home and abroad have confirmed that keratoplasty can reduce the growth of eye axis length by 50% compared to monofocal frame glasses, multifocal frame glasses, soft contact lenses and RGP by observing the growth of eye axis length for two years. The hyperopic defocus in the retinal periphery was more pronounced in children with axial myopia wearing frames. Therefore, children with axial myopia who have rapid axial growth are better candidates for keratoplasty. What are the age requirements for keratoconus? Generally speaking, the age of onset of early onset myopia is between 6 and 8 years old, so it is important to detect and intervene in children with myopic tendencies as early as possible. The age requirement for keratoplasty lenses can start at 8 years old. As long as there are no eye contraindications, such as conjunctivitis, keratitis, cone cornea, corneal degeneration, dry eye, glaucoma, etc., they can be worn by adults and preschoolers alike. Myopic children can slow down the rate and magnitude of myopia development by wearing keratoconus; adults can improve their daytime vision, avoid the trouble of wearing glasses during the day, and improve their quality of life. What degree of myopia is suitable for people with keratoconus? Traditional keratoplasty lenses are suitable for patients with myopia below -6.00 and astigmatism below -1.50D. With the continuous improvement of lens materials, design and technology, more and more people with high astigmatism can wear keratoplasty lenses to improve and enhance their vision, for example, Toric design and double bridge design lenses can be used for patients with astigmatism greater than -1.50D and less than -4.00D. Good lens positioning can be ensured, which in turn ensures corneal shaping. Are keratomileusis lenses suitable for children with long eye axes? Most people believe that only people with steep corneas are better suited to wear keratoplasty lenses to control the growth of myopia, and that children with long eye axes have limitations. In fact, the growth of myopia is more related to the growth of the eye axis. Compared to frame glasses, the correction of keratoconus is not a single arc, but a multi-arc design, corresponding to the aspheric surface of the human retina, which can not only correct the refractive state of the central retina, but also correct the hyperopic defocus of the peripheral retina, which is the principle that can effectively control the excessive growth of myopia in children. After examination, the optometrist believes that the child’s longer eye axis is compatible with myopia, and that the myopia is within the corrected range to be fitted with keratoplasty lenses. Do highly myopic patients have the opportunity to wear keratomileusis? The maximum number of keratomileusis lenses approved for registration by the State Drug Administration is 600 degrees. Patients with myopia above 600 degrees who wear keratomileusis lenses at night will have residual myopia during the day and will need to wear lighter frames to achieve optimal vision after the shaping effect has stabilized. A recent study by the Hong Kong Polytechnic University confirmed that this method can also control the growth of myopia in patients with high myopia, but the treatment period for patients with high myopia will be longer, usually ranging from 1 month to 3 months, to reach a stable refractive state, and the time and speed will depend on the individual’s myopia, corneal elasticity and wearing condition. Once the refractive error has stabilized, you can be fitted with the appropriate lighter frames.