In Australia they are known as fitover sunglasses,are available from optometrists and sunglass outlets, are a wraparound and sit comfortably in front of your glasses on your nose. They come in small and larger sizes, have two main eye lenses plus a smaller one at each side and give good glare protection. They also have a rubber strip along the top of the frame which is comfortable against your forehead and gives a good spalsh seal. I tie them on with a thin tube of wetsuit material.

the only way you are going to remain completely salt free is to go to diving goggles and they cost plenty for those needing prescription lenses. i used cheap safety goggles closing the air holes with tape but they didn't have the standard eye protection factor and your eyes really felt it at the end of a day on the water.

Fitovers are about $60Au, come with a velcro sealable softcase with a clip to go on a belt. I wish I had thought of them years ago.