Ring focus lenses blue light lenses 1.60 index defocus lens Delay myopia progression prescription resin lenses CR39 astigmatism
Ring focus lenses are the fourth generation of multifunctional lenses, also known as defocus lenses, or face-controlled lenses. The diopter gradually decreases from the center to the edge of the lens to reduce the shape deprivation in myopia, correct the focal phenomenon at the edge of the visual field, control the growth of the eye axis, and delay the development of myopia. The relative progressive multifocal lens not only changes the upper and lower diopter of the lens, but also changes the left and right luminosity, making the afocal lens more suitable for the prevention and treatment of juvenile myopia; especially for juveniles (4-16 years old), the prevention and treatment effect of myopia is remarkable. The earliest is Zeiss in Germany, which was developed and produced around 2010. By 2018, the technology has spread, and many lens factories have produced such lenses. Costs fell, and the market responded favorably.