Does bright environment strain eyes more than dim?

Question

I'm trying to figure out how to modify my working conditions so that I can program longer without harming my eyes. Because doing so experimentally hasn't given conclusive results so far, I decided to ask for studies in this area.

Does looking at a bright screen in a well lit room strain eyes more than looking at dark screen in a dark room for prolonged periods of time? Or is there a middle ground somewhere in-between that is most harmless? Or is it a combination of contrasting screen/background?

I'm not asking for medical advice here. I already went to several doctors and they gave me different, sometimes contradicting answers, so I'm just looking for research.

Answer 1

I think the principle is "everything in moderation". Environment should be not very bright and not very dimmed. Also, the contrast should be moderate too, i.e. having bright screen in dark room is not good. Also, he type of work should not be very constant, i.e. you should sometimes change looking at the screen to looking in the window and similar.

Remember, that the light is required for stimulating the brain activity.

Answer 2

Here's a link from the Oklahoma State University's Environmental Health and Safety suggestions on office ergonomics. It's got the following:

If the light in the work area is too bright or too dim, the human eye has to work extra hard to compensate for these harsh environmental factors. People may not even be aware that their eyes are under duress, but over time they may develop symptoms of eyestrain.

Solution: Use indirect, ambient lighting and an adjustable light source at the desk, where extra illumination is required.

Most sources seem to discuss the effect of too much brightness, although there's a good chance that's a function of the fact that we often need interior lighting. Where there are suggestions, it's usually to achieve some level of parity, such as from here:

Adjust the brightness of the display so it's approximately the same as the brightness of your surrounding workstation. As a test, look at the white background of this Web page. If it looks like a light source, it's too bright. If it seems dull and gray, it may be too dark.

As a side note, I would recommend f.lux. It's a piece of software that, outside of daylight hours, adjusts your screen's color. I can barely look at another computer after dark anymore.