Avoiding eyestrain often requires changes to the way you work; in particular, how you use digital devices.
Eyestrain can be minimised by taking a short computer break every 20 minutes. Also, you should be mindful of not sitting too close to digital screens.
If it persists you should see an optometrist. The symptoms might indicate there is an underlying problem with your eyes.
In this case, optometrists usually prescribe reading glasses or even glasses with special coloured lenses to eliminate eyestrain.