I called 911 when it happened since I was losing vision and didn't want to risk driving to a hospital. By the time the paramedics got me to the proper hospital (the ambulance was turned away from the first one they tried since they didn't have an optometrist) the "nothing" had become neon...
I have an experience that might shed light on the issue.
Once I had a problem where I began to lose sight in my right eye while I was at home looking at my computer. When this happened, a black spot did not begin to grow where my vision was disappearing, rather-no input was received at all...