Yes, poor light can cause eyes strain.When you are in a poor lighting, your eyes will do a lot of job to adjust the light. First, the rod and cone cells on the retina begin to produce more light-sensitive chemicals. Second, the iris muscles relax, which causes the opening of your eye, the pupil, to become very large. So when your eyes are working this hard for a long period of time, it will cause eye strain.
Yes, the poor lighting will cause your eye strain because of the not right position on the retinal on your eyes. Your eyes will get the weak reaction under the poor lightning. You should take great care of your eyes. You'd better be in the room with bright light when you see something. Or else, your often eye strain will cause your eyes problems.
It can definitely cause eye strain, but reading in excessive light may also be harmful.
When you are reading with poor light, your eyes need to operate harder. Your pupils need to extent or shrink more frequent than the normal time. This is the reason of the eye restrain.
By the way, reading in poor light for long hours causes headache and strain and pain in the eye. However, these are just temporary discomforts that go away once you sleep or take a break.
But do not keep this bad behavior for long, which would make your eyesight dropping and put your health in danger.