Negative spherical cheapest eyeglasses lenses are used to correct the vision of myopic eyes, which are the transparent bodies within the eye that allow light to pass through the refractive medium - the cornea, aqueous humor, crystalline lens, and vitreous body.

The negative spherical lens has a strong ability to bend light when the focal point falls in front of the retina. By using a concave lens to reduce the eye's refractive power, the focal point is focused on the retina, forming a clear object image. The center of the negative spherical lens is thin, and it becomes thicker towards the edge. It is best to have a frame model that is close to the actual pupil distance of the eyeglass online wearer so that the center shift of the glasses during processing is small.

A spherical lens is used to correct hyperopia and presbyopia. Hyperopia uses a convex lens to increase the eye's refractive power, so that the focus falls precisely on the retina, and clear images are transmitted to the brain through the optic nerve. The center of the lens is thick, and it becomes thinner as it reaches the edge. Try to choose small eyeglasses online for cheap frames.

Spherical prism lenses are used to correct astigmatism, and each direction and optical center on the lens has the same degree. Spherical prism lenses add a prism lens to the spherical lens, and the corresponding amount of prism lens is added in a specific direction. It is best to choose a full-frame lens.

It is recommended that the spherical lens has a small degree of deformation, is close to the actual object, and is easy for the eyes to adapt to. Made of injection molded plastic, it is not resistant to high temperatures. Once the glasses deform, they cannot be adjusted and are generally used as decorative glasses.