I have practiced the Visualization skill these days,the first few days I can't see any thing when I colsed my eyes,then after some trying I can see some light spots in the center of my closed eyes.I can't tell what kind of color of the light,so I try to make the light brighter and try to change its shape,after some trying I can make it brighter ,but the light spots constantly flicker and can't be changed shape.I think I should find some methods to stop its flickering ,it is such annoying,I can't focus to change its shape.