How is Zhang Canzi blind?

There are many speculations about Zhang Zifan's eyes. One of them was the corpse ancestor General Zifan who invited him to save Li Xingyun at the cost of Zifan's eyes. Because Lin Xuan said in the play that he hasn't seen Zhang Zifan for more than half a month, is it possible for old Li Can to play dead and escape? Part of the reason is that Zifan gave his eyes to the general and asked her for help.

There is also a saying that Zhang Zifan should be inspired by the way of playing chess and gain insight into the world situation as an outsider. Therefore, he wrote to Shu Wang and others and said his own speculation about the future, including the northern expedition of the desert. It seems that the female emperor also learned the way of divination from playing chess, and can speculate on the future, but she was blind because her outdoor machine was attacked by herself.