There have been many inventions, like the e-book reader, that allow to look at a steady screen for long hours without compromising the optical organs.
As more e-book readers are sold, the prices will lower to the point of being accessible like a cheap $15 cell phone. The Amazon Kindle is sold in USA for $60 .
If one wants to edit text or other high contrasting images(which are the most stressful for the eyes), e.g. a notepad file with a bunch of subtitles with their timings, like in my case:
The requirements are none. Just press «Shift»+«Alt»+«Print Screen» and you will prompted with a message asking whether you are sure to enter High contrast mode. Once you have clicked on «OK», the background which tends to be white will be black, and the text which tends to be black will be white. This is much easier on the eyes.
The other aspect you can change in your computer monitor and graphics card options is to increment the vertical update frequency to the maximum available for the hardware combination. Most modern monitors support 60Hz, but the high end ones may reach 120Hz and perhaps 240Hzs. The higher the frequency the less eyestrain you will experience.