Seeing Blue Lights

I have been seeing flecks, sparkles and flashes of light for the past few years.  The intensity has increased a bit over time, but they are mostly small and last for a fraction of a second.  They are often blue, sometimes white.  Sometimes they appear almost as tiny orbs, but mostly like sparkling sand.  I remember when I first started to notice them.  They mostly appeared to my left at first, and at a distance.  Now I see them from time to time on both sides.

They're not what's known as eye floaters - those spots you may sometimes see moving across the surface of your eye that appear within your field of vision.  I've seen those from time to time and they're quite different, being dark grey or black in tone and have a symmetry of movement that can be observed for several minutes and is easily predictable.  These light flashes are different.  They are intense enough that they get my attention every time, forcing me to look at them before I realize that I'm looking, and by then they're gone.  Several friends have told me that they see these kinds of lights occasionally as well.  There's an interesting forum page in Pavlina where people share some possible explanations.

Update: June 2010 - See update in post "More Blue Lights" as these appearances have started to increase for me once again.