I'm not expert on this, and would love other input if others disagree, but I took this question to heart years ago because my day time work was all computer, and then my night time scholarly pursuits were all computer. ~ 12-15 hours / day of computer.
What I remember reading online was that computer monitors don't emit any (really) harmful radiation. It's not UV, or anything like what comes from the sun. I remember reading that it is recommended that you look away from the monitor, at least briefly, every so often.
In regards to strain, that is actually one reason I *do* prefer computer monitors over books. I have no control over the font size of a book, and good lighting is usually an issue. Both of these issues are negated with my computer screen. I can control both the font and the light output.
Again, someone with more expertise, feel free to refute. But I remember looking this up out of concern, and being quite relieved that I wasn't being zapped with harmful radiation. Just need to remember to give the eyes a break.
Like Tim Jenney, I had gone to purchasing most books in digital format with Accordance being my preference by far. However, I am moving more to read books again because of the risks to the health from screens.
Here are some issues:
1) The flicker effect from computer screens, etc. has a deleterious effect on the mitochondria. The flicker effect will lead to melanopsin dysfunction.
2) The blue light from computer screens, tablets, smart phones, etc. will also lead to melanopsin dysfunction.
Retinol is loosely bound to melanopsin. When that bond is broken, the free retinol will do major damage to photoreceptors in the body creating a cascade of health effects.
The artificial blue light from the screen will also lower ocular dopamine and ocular DHA.
Blue blocking glasses do help when working with Accordance.
Iris Software also has a product that will cut the blue light from the screen thus making Accordance safer.
3) Non-native electromagnetic fields (nnEMF) emitted from a computer also has health effects.
When I measured my Macbook Pro, I found there were extremely high magnetic fields (plus RF as well).
To help mitigate, I use a wired keyboard and mouse to give distance from the screen and don't charge the laptop while I'm using it. It is also good to have some ambient sunlight while using the laptop.
The printed price of this Aramaic lexicon is quite reasonable and I did buy it. But it doesn't have the capacities of use like with Accordance.