The center (the position of the eyes is the eyepoint) is the thinnest when it comes to lenses with myopic power, and it gets thicker as the distance from the center increases.
The area diagonally downward from the portion of the eyeglasses by the ear is the thickest (if there are no effects of astigmatic power) because it is in the farthest position.
This change in thickness rapidly increases as if forming a parabola rather than being directly proportional to distance. The thickness increases at an accelerated rate as the power increases so even small differences in distance increases thickness greatly.
This is why eyeglass shops recommend selecting smaller frames.

In order to have lenses that are even just a little thinner; (1) frame sizes can be decreased, (2) thin lenses can be chosen, or (3) lenses with thin designs can be chosen.
Therefore, please note that even if you choose thin lenses or lenses with thin designs with the same power, there is the possibility that you will get thick lenses if the size of the frame you choose is larger than your previous one.

An indication of the optimal type of thin lens is in the refractive index.
Spectacle lenses bend light and change focal length so lenses with higher refractive indexes that have strong bending force can be made thinner even if the same power is chosen.
The refractive indexes of our single-focus plastic lenses are 1.50, 1.60, 1.70, 1.76 (thinnest in the world), and those of our glass lenses are 1.604, 1.705, 1.807, 1.892.

There are also lenses with aspheric designs offered as lenses with thin designs that have been designed to be made thin while suppressing distortions in the surrounding parts.
Aspheric designs include double-sided aspheric lens designs and (single-sided) aspheric designs, so thinness comes in the order of double-sided aspheric lens designs, aspheric designs, and spheric designs.
Our plastic lenses come with refractive indexes of 1.50 and 1.60 with spheric designs, all refractive indexes with aspheric designs, and indexes of 1.60, 1.70, and 1.76 with double-sided aspheric lenses.
The spheric designs of glass lenses are compatible with all materials and 1.807 and 1.892 are compatible with aspheric designs.

There are advantages and disadvantages whether you choose from plastic lenses or glass lenses.
Most people today find plastic lenses appealing because of the advance in how thin they can be made and how resistant they are to scratching, but some still choose glass lenses because they can be made thin with more power.

One way to choose is by checking the thickness that is right for you by lens type at your eyeglass shop ahead of time after deciding on your power and frame.
Most shops exchange information with manufacturers online. Although this may take time when considering settings and the transmitting of information, we feel that this can serve you very well.
Please see this information as reference data that serves only as rough indications because it is based on calculations of thicknesses at certain portions.