让我先回顾下在印刷术之前的视力矫正是什么样的。

First let me back up a bit and talk about vision correction before the printing press.

youdao

但是书就不一样了…印刷和装订一本书很便宜。

But a book... a book is cheap to print and bind.

youdao

它有带编号的书页，目录，照片还有图片，跟一本印刷书没什么两样。

It can have numbered pages, table of contents, pictures and graphics, exactly like a printed book.

youdao