I believe many people who wear cheap eyeglasses near me have encountered this situation. Why did I choose the same refractive index lens as last time, and why did I make the lens thicker this time?

At that time, because you chose a larger frame size this time, the lenses became thinner towards the middle and thicker towards the edges. The lens is such a small piece, thin in the middle and thick at the edges.

Under the same refractive index, the smaller the frame, the thinner the lens. For those with small pupil distances, do not choose a large frame, especially for those with height. Patients with hyperopia, on the other hand, have thick lenses in the middle and thin edges.

Let's talk about the lenses! How to choose a pair of lenses? The lens, the soul of a pair of glasses, can be said to be crucial. You need to understand some basic knowledge about lenses to choose a good pair of lenses.

The lens is divided into the refractive index, material, and Abbe coefficient. First, let's talk about lens materials. There are three common types of lens materials on eyeglass mart. Glass, resin, PC materials.

Due to the different functions of different materials, the choice of material for lenses should be determined based on guidance and personal needs. The advantages of glass lenses are thin lenses, high clarity, and good wear resistance.

Resin lenses are relatively light, not fragile, and highly safe. Their transparency is similar to that of glass lenses but thicker than glass lenses. PC lenses are considered the lightest among common lenses, have strong impact resistance, and are suitable for frameless frames and those who frequently engage in outdoor activities.

How to choose the refractive index depends on the prescription frame size, lens function, lens parameters, and one's own needs for wearing glasses.