What is "mirror eye distance"? What is it related to wearing glasses?

The definition of "lens to eye distance" is the distance between the inner surface of the lens and the vertex of the cornea.

The lens to lens distance of a contact lens is 0 because it is attached to the surface of the cornea. The effective degree of the lens is determined by its degree of contact. The eyeball is viewed through the optical center point to the maximum extent possible.

The visual effect hardly shrinks or deforms,
The closest imaging effect to reality,
Wide field of vision, just like naked eyes.

When we perform optometry, both the comprehensive optometer and the trial frame default to the degree of 12mm lens eye distance.

The board frame, as an integrated nose rest, should have a mirror eye distance of less than 12 millimeters when worn on the face.
The distance between the eyes of a metal frame is generally greater than that of a sheet frame

1) Contact lenses do not have any discrepancy issues, even if the degree difference between the eyes is significant, they can still be worn comfortably. This is because the distance between the lenses is almost 0, which is infinitely small. Even if the distance between the lenses is not that large, it will definitely be more comfortable. Especially for people with large differences in binocular powers and anisometropia, choosing a sheet frame is more comfortable than a metal frame because the distance between the lenses is small and the difference is small.

2) If we approach the window and look outside, the field of view will be very large, and the window frame will not be visible. If we take two steps back, the outside view will shrink and the window frame will also be visible.

Wearing glasses is the same principle,

The panel frame has a smaller eye distance, which broadens the field of view and allows for more comfortable viewing through the optical center point. It can be imagined that the distance between the mirror eyes is infinitely small, and can only be seen through the center point. The metal frame has a large distance between the lenses, and the field of view will inevitably shrink, making it easy for the human eye to see the edges of the lenses. The imaging effect of the edge part of the lens is very poor. You can pull your glasses far away, and the object you see is completely twisted and deformed, that's the reason.