Generally speaking, anxiety will easily leads to insomnia, but it may not cause poor vision. Poor vision can be caused by overuse of the eyes, incorrect posture when people are reading or watching TV, eye degeneration such as cataracts, malnutrion in the eyes, over exposure to the ultraviolet rays, and many other eye diseases. If you feel your vision falls down sharply, you should go to the ophthalmologist for an examination to see what the exact problem is and get correspondent treatment.
Well, yes, anxiety can just cause poor vision in your eyes, so that is why some people get photophobia, when they are anxious. Generally speaking, when you have anxiety, it will lead to high blood pressure. In that way, it will just have some effect on your eyes, making your vision become poor. For example, photophobia may occur because of it. And you need to know that photophobia is eye discomfort in bright light. And if you get it, it can be dangerous and annoying. By the way, severe photophobia may occur with eye problems and can cause severe eye pain even in relatively low light. Anyway, just be careful about it.