Make sure your glasses or contacts prescription is up to date and good for looking at a computer screen.
If your eye strain won’t go away, talk to your doctor about computer glasses.
Move the screen so your eyes are level with the top of monitor.
Choose a comfortable, supportive chair. Position it so that your feet are flat on floor.
That lets you look slightly down at the screen.
Try to avoid glare from windows and lights. Use an anti-glare screen if need.