Dark spots in vision when looking to the sides or up
When looking far to either side or upwards I notice two darker, circular patches in my vision (one with each eye open by itself). These patches correspond to where the blind spots in my vision are, which I was able to determine by moving around a sheet of paper with a dot on it, and when the dot is positioned where my vision is different, it disappears. I've found nearly a dozen stories online from people who notice the same thing in their vision, none of whom were diagnosed with anything when consulting with ophthalmologists or neurologists, nor did they receive an explanation as to why it happens. One thing I noticed that was common to almost all of the posters, was that these people suffer from anxiety, which I do as well. Is this something I should be concerned about, or is it common phenomenon when straining one's eyes that most people just don't notice?