I asked my optometrist whether reading/watching in low light was really bad for one's eyes, and he said it really doesn't make much difference. he did also say that there's more nearsightedness now than in the days of say, hunters/gatherers because we have corrective lenses, and those with bad eyesights would've walked off a cliff and wouldn't have reproduced to pass on their genes.

Interesting theory, which I'm sure has something to do with more nearsightedness in the modern times.