It may be eyestrain. Eyestrain can be caused by excessive use of vision. I can recommend you some methods to deal with sore eyes. First, adjust the light. When you read books in din light, it will not hurt your eyes, but if the light does not provide enough contrast, it will make your eyes fatigue. So you should use the sift light with clear/dark contrasts.
Second, timely rest, if you work in front of the computer for 6-8 hours, you should have 2-3 hours' rest or just let your eyes away from the computer for 10-15 minutes.
Third, adjust the brightness of the computer screen. The fonts and figures on the computer screen like a small light bulb, which directly beat your eyes. Therefore, you need to adjust the brightness. Fourth, let your eyes have enough rest.
Finally, blink frequently. Eyelid is your private eye masseur. Blink 300 times a day can help clean the eye and give the eye a massage.