At present, myopia is becoming more and more serious among young people in China, and the trend is towards a younger age. Many students and parents are worried that myopia will get deeper and deeper as they grow older, so a significant number of people choose to have myopia surgery for the sake of higher education and employment. In this case, to control myopia or treat myopia, keratoplasty can be the ideal choice.
Orthokeratology is a type of contact lens that is highly permeable to oxygen and has a shaping function, its full name is “Orthokeratology”, formerly known as “OK” lenses, is a kind of digital precision calculation design and processing of multi-arc reversal geometry type Orthokeratology, formerly known as “OK” lenses, is a geometric, multi-arc reversal contact lens designed through digital precision calculation. Originated in the United States, it has been developed over the past 50 years and is used in 34 countries worldwide. The lens is worn only at night and slowly changes the shape of the cornea through hydrodynamic forces between the tears and the inner surface of the lens, flattening the curvature of the cornea and gradually reducing myopia and astigmatism, resulting in clear, all-day vision. It is known as the “technology that controls and corrects myopia while sleeping” because there is no risk of surgical trauma and irreversible post-operative sequelae. For each wearer, we adopt a standardized fitting procedure: pre-fitting examination (naked eye vision, computerized optometry, subjective optometry, slit lamp examination, corneal curvature, corneal topography, corneal thickness, intraocular pressure, lens fitting, fluorescence evaluation, and lens fitting). Regular review including the above mentioned items is done on the first day, second day, first week, second week and monthly thereafter, especially the fluorescence evaluation of the lenses, primary optometry, and corneal topography examination are the deciding factors for lens replacement. Due to the regular review and complete examination equipment, the entire treatment process can be carried out safely without irreversible side effects. 70-80% of people can reduce their myopia by 200-300 degrees within the first month, with an optimal reduction of 400-500 degrees, and after the treatment is completed, the reduction can be maintained basically by consolidating the lenses.
Corneal shaping lenses can be used in a wide range of conditions, with adolescents with less than 600 degrees of myopia being the main treatment group; in addition, monocular myopic refractive aberrations can be reduced by wearing frame glasses to promote the formation of binocular monovision; myopic patients who often participate in recreational and sports activities and do not want to wear glasses during the day; corneal shaping lenses are also particularly suitable for patients with low to moderate myopia who are engaged in special occupations and need good vision. They are also particularly suitable for people with low to moderate myopia who are in special occupations, who need good vision and are not allowed to wear glasses or are unwilling to perform myopia surgery, such as police officers, soldiers, deep-sea divers, pilots, etc. It is also a beautiful “weight” for myopic patients who love beauty and are timid and do not have the courage to step into the operating room; however, it should be reminded that the corrective effect of keratoplasty has a certain degree of reversibility, and the shape of the cornea will gradually return to its original shape once the wearer stops wearing it, and the speed of its return is related to the refractive condition of the eye and the length of time the lens has been worn.
Changes in corneal topography after good fitting
Not suitable for wearers: 1. patients with severe dry eye, conjunctivitis or other eye diseases; 2. people with corneas that are too flat or too steep (corneal curvature less than 38D or more than 48D are not suitable); 3. people with astigmatism greater than 200 degrees; 4. people with axial myopia (i.e. pathological myopia, congenital myopia) caused by the growth of the eye axis; 5. people who cannot keep up with follow-up examinations within one month of wearing the lens and cannot comply with the wearing time; 6. people younger than 10 years old who cannot take care of themselves after wearing the lens. Those who are younger than 10 years old and cannot take care of themselves; 7. Those who have undergone keratoconus surgery, have worn contact lenses or other OK lenses should ask the doctor for guidance.
Comparison between OK lenses and keratomileusis
OK lenses
Keratomileusis
Legitimacy
Not approved for registration by SFDA
Registered by SFDA
Material
Low oxygen permeability, does not meet the requirements for night wear
High oxygen permeability to 100, DK value >90 (ISO standard)
Design
Four zones and four arcs, poor anastomosis
Machining process Low machining precision
Four zones and seven arcs, good fit
Latest CNC machine, high precision
Function
Principle
Based on the mechanical pressure of the lens on the cornea
Based on the hydrodynamic effect generated by the uneven distribution of the tear layer between the lens and the cornea
Production
Unorganized production at home and abroad
Fitting process No standardization
The only domestic custom-made production of strict fitting and re-inspection of the standard operating procedures
After-sales service
Service
Confusion
National standardized management