Avoid Micro-Focus Adjustments
Items within a couple of inches in depth do not require your eyes to refocus. Use this to your advantage by keeping everything at your worksite at the same depth.Switch Depth Slowly
Rapidly switching your focus can cause a lot of eye strain. When you have variety of depth in your task make sure the transition back and forth is slow. In other words you want to stay at one distance for a while before switching to another. A change of at least 20 seconds is good. And only one change every couple of minutes is better.Eye strain can be caused by something as insignificant as dry eyes. Dry eyes can be caused by something as insignificant as not blinking enough. Make sure your viewing angle is comfortable and that you blink and take breaks. If your eyes are still dry then try some artificial tears. Note that red eye reducers are not artificial tears.