What Causes Flashing Lights At The Periphery Of Eye?

Hello. I am a 65year old male. Last night in the dark in my garden I noticed flashing lights on the periphery of my right eye (as if someone was using a laser pointer near me).This evening after using the computer, this occured again with more frequency. This seems to occur more if I move my head from right to left, left to right rather than up and down I have not injured my eye in any way. Kind regards Ray Quinn