Without a photograph or more extensive history it is hard to answer your question. In most cases, assymetric eyes can be made to be more symmetrical. If one eye is becoming bigger, it needs to be urgently evaluated by an Oculoplastic Surgeon. Very often, this is a sign of thyroid eye disease. Another cause of an eyelid becoming bigger is a growth or inflamation behind the eye. Sometimes, the larger eye is actually normal and it seems bigger beause the other eye is becoming smaller. The bottom line is to see your eye specialist and discuss the appropriated course at that time.