I believe that you may have occular migraines? The white I think is what is called the aura. It not not have to be followed by a migraine. My dad gets these.I want to say he got thim from working on tiny objects WHILE wearing his glasses? I will ask him tomorrow. But if that IS what is happening, don't worry. I don't know what you can do for it, but at least you can look it up! I hope this helps!!!
Take care and good luck :)