There is no standard for this. It depends on your own choice. If you want to be thinner, you can choose a high refractive index. If there is no requirement for thickness, you can choose a low refractive index. The higher the refractive index, the thinner the lens and the higher the hardness. If you are at 375 degrees, it is no problem to use the refractive index of 1.56. The reason why I think the lens is thick is mainly the shelf, because the myopia lens is a concave lens with thin middle and thick sides, so I choose it.

As for aspheric surfaces, there is generally no difference between spherical surfaces and aspheric surfaces within 200 degrees. If the temperature is above 200 degrees, it is still valid. Compared with spherical lens, aspherical lens has smaller peripheral aberration, which makes things more real, and at the same time, the deformation of your eyes is smaller and more beautiful when others look through the lens.