I have this random blindness?!?

sometimes i will go slightly blind in one eye its really weird, its only like one part of one eye though and i have no wats up. i dont have perfect vision either and i have a lazy eye in one eye, but thats not the eye thats get the "blind spot" i guess you could say. Its similar to when you look at the sun for a few seconds but longer and happens randomly. Usually it happens in school earlier in the day.