I'm with saw101. Storage conditions for any media are paramount to it's functional lifespan. Optical media stored in conditions that are consistently comfortable for human beings have a very, very, very long functional life. I have several CD-Rs and CD-RWs that are decades old now that still function exactly as they did when first burned.
They've been stored in a desk drawer, indoors, with the same climate controls that keep the residents of the house comfortable. For a good chunk of the spring, parts of summer, and early fall that means no artificial climate control.
I hasten to add that I doubt that a coating of clear (or even colored) fingernail polish on the outer edge of optical media would do any harm. It's quite far enough away from the end of the readable area. I have no idea if it has any benefit, though, and doubt that it would unless the media were stored in less than ideal conditions. In addition, depending on the maker, there were lots and lots of writable optical media where the carrier layer is right on the top of the disk itself. I have an old Hi-Val brand CD-R right in front of me that's no longer functional because it was stored where things were "sliding along" its upper surface when a vehicle was in motion and where there are now "blank areas" where the reflective media scratched off. (And, yes, they were ultra cheap and intended as disposable.) I have a number of others from this batch which were stored with a bit more care and they still work just fine.
Brian AKA Bri the Tech Guy (my website address is in my profile) Windows 10 Home, 64-bit, Version 1709, Build 16299
Here is a test to find out whether your mission in life is complete. If you’re alive, it isn’t.
~ Lauren Bacall