Ethel's link is another instance of history repeating itself. It seems we never learn. Back in the 1950s, when more and more people were buying TV sets for the first time, the newspapers were full of advice about not watching TV in a dark room. The use of something like a small table lamp to illuminate the wall behind the TV was invariably recommended.
Incidentally, TV screens had rounded corners in those days. It was said that this allowed more eye movement, and helped prevent eye strain caused by the viewer's eyes becoming locked to the screen. Where are such screens today?