I was sent an email asking for advice on eyestrain. I am so not the person to ask. Yesterday I started work at 9am and worked through until 1.30am and I felt as though I had eyes on stalks by the time I went to bed. My computer screen is set to shut down every forty minutes and the idea is that I get up and do something different for at least ten minutes. But there is so much work on the new book that I cheat - I can't help myself - I just press the button and keep going. Eyestrain is not so much a problem for me as dry eyes and sometimes styes - it seems I don't blink enough. So, at night and in the morning I bathe my eyes with hot water and that helps a great deal. I don't use eye-drops. My mother who was a professional cloth burler and mender used to have problems with dry eyes and styes just the same. So, my advice is to blink - and to relax your eyes - gaze into the distance every half hour or so. But, this is not the advice given in the 17th century when it was:
Sitting at worke cast not aside your looke,
They profit small that haue a gazing minde:
Keepe cleane your Samples, sleepe not as you sit.....
Maybe you have some helpful advice to offer us?