Don't look down on flat little boxes and ellipses. They are a form of eyeglasses online cheap progress. The edges and corners make the processing unnecessary and tight, ensuring that the lens does not rotate off-axis.

At this point, we are qualified to discuss the issue of stress and consider whether we can loosen it a little bit. Before that, haha, what kind of bicycle do we need?

The flattened and elongated shape also significantly reduces the area of the cheapest eyeglasses lens. It should be noted that the thicker the edge of the concave lens, the smaller the volume. So, the glasses have become lighter!

This was very important at the time because these materials were not used before they were applied. Glass, but it's very heavy! We all have experienced that the adaptation time of contact lenses (without astigmatism) is much shorter than frame glasses.

Even if the degree of the frame glasses remains the same, just changing the mirror angle and tilt angle (which some people are very sensitive to) can cause dizziness.

It takes at least one day to adapt. It usually takes three days for improvement. Because contact lenses have almost no aberrations. And frame glasses, every time the position changes, the aberration is different, and the brain needs to redesign the brain compensation algorithm!

We can use the edge of frame glasses to select a building and see that it is curved, but we are accustomed to it and do not feel dizzy because of the powerful brain compensation function. And if you put these glasses on someone who is not nearsighted, they will immediately spin around. It's just that the brain algorithm is different.