Spherical lenses refer to the cheapest eyeglasses online lenses with convex or concave shapes cut from a sphere. Due to the unavoidable occurrence of aberrations (especially astigmatism and image bending aberrations) in spherical lenses, a lens called nonspherical (single-sided nonspherical) has emerged to compensate for the shortcomings of spherical lenses.

Nonspherical lenses refer to rotating surfaces (such as parabolas) with the same noncircular cross-section on all meridians. Its biggest advantage is that there is no distortion of objects in the edge field of view, and the edges of the lens are thinner than ordinary spherical lenses.

Nonspherical lenses are indeed closer to the naked eye's vision, with less deformation at the edges and a larger field of view, making them a mainstream configuration. Moreover, nonspherical lenses are already very mature, and the price difference is very small. But not everyone can adapt, and it cannot be ruled out that some people's eyes can only adapt to spherical discountglasses lenses.

So, there is no saying that nonspherical surfaces are superior to spherical surfaces, it depends on individual adaptation. What is special about double-sided aspherical lenses? Double aspherical lenses have a high Abbe number, similar thickness and weight, higher clarity, and a wider field of view.

The popularity is not yet high. In the future, double aspherical lenses will become mainstream, and the prices of spherical, single aspherical, and double aspherical lenses will become increasingly close.

Before the invention of eyeglasses, people's lifestyles and professions were constrained by their visual abilities. As people's reading time increases, the demand for good eyesight becomes stronger. The continuous increase in consumer demand has promoted the development of lens technology.