In my opinion, the salt water will not damage your sunglasses. And you can wear them when you go to swim. As we know that the lenses of sunglasses are made of special material which can resist much damage. Especially, since sunglasses are usually used in the beach or ocean, the designer and the producer have definitely considered of this kind of problem. So you don't need to worry about it too much. But on the other hand, when you go and swim with your sunglasses, you should also pay more attention to care and clean them for there are many other dirty objects which can damage your sunglasses.
I think the salt water will damage the glasses especially itâ€™s made by resin. The raw material resin is containing calcium, magnesium, potassium etc. They are the mineral and natural substance. From the chemical action, we know the acid-base neutralization will be happened when the salt meet the mineral substance. Apparently, the salt water will truly damage the resin glasses when they meet.
As a matter of fact, salt water, I mean, if properly made, will not damage sunglasses, because you are just using it to wash it, right? And salt water will not cause chemical reactions with glasses. Perhaps in this way, sunglasses could be much cleaner. So, you can just ease your mind and use it whenever you want, ok? But you should not get them soaked in salt water for too long.
Generally speaking, it doesn't matter. We even often use saline solution to get our eyeglasses disinfected, don't we? But to make sure the dirt and grim left by ocean water won't stay, you had better wipe your sunglasses with a drop of mild dish soap with warm water. If you spend a lot of time in or on the ocean, get in the habit of rinsing your sunglasses off periodically under the tap. It will extend the life of your lenses.