What Problems Do Bifocals Have
Bifocals have two different optical powers: one for the upper segment and one for the lower segment. They typically have a significant difference in optical power between these two segments of the lens.
The upper segment is for distance vision, and the lower segment is for near vision. The issue with bifocals is that when you look at a blackboard and use a computer, you use the distance vision part, which is the upper part of your eyeglasses.
So when you use a computer, you end up looking straight ahead as if you are looking at distant objects. However, you actually want to look at the near computer screen. Therefore, using the upper part for distance vision and the lower part for near vision can be problematic.
I don’t think there is a perfect pair of bifocals that allows your eyes to see what you want to see barely clearly. It might be better to prepare two or three pairs of eyeglasses to adapt to your normal routines and see things clearly. This way, you might be able to improve your myopia over time.
However, if we think carefully about this, if I were to design bifocals for myself, I would want the upper segment to be 175 degrees less and the lower segment to be 200 degrees less. This would allow me to use the upper segment perfectly for computer use and the lower segment for reading books or using a mobile phone. So, in some aspects, the concept of bifocals is innovative. The people who invented it understood how myopia works, but not completely.