Hi, I just have some thoughts that might be of interest to you.
Do the dots move? Could they be described as looking like a swarm of small insects (the movement pattern)?
If so, i'm thinking that you may be seeing the white blood cells in your retinal circulation. This has an appearance similar to what you have described. It happens when white blood cells pass through your capillaries - the light can be seen through the wbcs, hence they appear as bright spots in contrast to the darkness when red blood cells are passing through. If this is the case it's totally normal to see these, especially on the backgrounds you've described.
Try this experiment....
Look at a blue sky/white paper (whatever is convenient) and look at the rate of movement.
Now do a few minutes of physical activity (enough to raise your heart rate and increase the rate of blood flow)
look at the same background.
If the spots are moving faster they are likely white blood cells.
Just a thought - another theory (hope it helps)
take care.
T.