I find that a low helmet visor keeps most rain off. I ride all winter, at night, in the rain, and Ive never had any problem with regular glasses.
Most people try to avoid deep scratches in their eyewear, but the real problem is from micro scratches which come from rubbing them clean. These cause any point source of light to flare. I wash my specs under running water with detergent, then dab (not rub) dry.