If you only have eye pain when reading but not at other times, you may be suffering from refractive errors such as farsightedness, astigmatism or a large difference in refraction between the eyes, which can lead to eye pain.
The symptoms can be relieved with proper rest or correction with appropriate glasses. In addition, if you read books for a long time, you may also suffer from visual fatigue and eye pain. It is recommended that you take a relaxing look at the far end of the book for 10 minutes every 45 to 60 minutes.