Explanation: The other answer said that it was something that someone who is approaching death may see, but what about someone with schizophrenia or someone who is used to hallucinations. Who is used to seeing what is not there? It may not be the right answer but its something to think about.
The reason why people use folic acid supplement is to prevent Anemia, stroke, and heart disease . Consuming the supplement before the child is born could also enhance the development of brain and spinal cord of the infants. The supplement cannot prevent blindness.
It depends on what causing it. the only thing I can say is to drink plenty of fluids but I would recommend to go see a doctor, if you are unsure or worried.