Well, in my opinion, reading too much can just lead to astigmatism, so you should be careful about it. Generally speaking, we know that astigmatism is merely a visual condition of the eye that is caused by its shape. And according to some researches, it can result in an eye that has two different powers, and also it splits the focus point into two different partial focus points. So if you read too much, it can just cause eye strain. And then eye strain can lead to astigmatism. At this moment, it also may lead to blurry vision, which is the most common symptom of astigmatism. By the way, you need know that shadow images, eye muscle spasms, eyestrain, and headaches can be possible too. Anyway, you should pay more attention to it.