What your mum says is reasonable. Smoking is very bad for your whole body health which may cause the night blindness. Smoking will cause the damage of your visual nerves. That is the reason to cause the damage of the night vision. You need to stop smoking and eat more food with vitamin A to improve the night vision. You should protect the eyes carefully.
I don't want to persuade you to listen to your mom, but I do have some warnings for you.
First of all, I guess you know that the night blindness is relevant to the health of liver and the intake of vitamin. Of course, there is a lot of dangers that smoking can bring, but what I want to aware you is that smoking can enforce the workload of your liver. Smoking frequently can influence the metabolism of your liver lipid, which will increase the bad cholesterol and decrease the good one so that will make your liver hard to detoxicate tne toxin. And a damaged liver means a bad blood provison which can cause vision recession and other eyes problems. At the same time, the nicotine and tar in the tabacco will consume plenty of several different vitamin. What's more, smoking can hinder the intake of vitamin and even destroy that you have taken in. That's why the smokers are easy to get scurvy. And once we are lack of the crucial vitamin and worse blood provision we can get the night blindness.
I have to confess that your mom is medically right.
Smoking is really bad for eyes but night blidness. Smoking in a long time may cause yellow eyes, irritated eye and eye pain. Sometimes allergies may also happen. Night blindness is a condition making it difficult or impossible to see in relatively low light. Night blindness often caused by vitamin A deficiency, pathological myopia and oguchi disease.