80% of the women’s feet I see, are wearing polish on their toenails. Unlike fingernail polish which rarely lasts more than a week, toenail polish is often left on for weeks at a time, sometimes until it wears off completely. Toenails need air to thrive and prolonged toenail polish can cause a surface type of fungus to inhabit.
These are pictures of surface toenail polish fungus, before and after the coarse side of an emery board files it away. If left unchecked, it can contribute to a worse type of fungus which can’t be filed away.
Dr. Jenny Sanders Shoe Blog 
Hello Dr. Jenny, after seeing these photos and reading your analysis, I am astonished to note that this has happened to me – and I filed away the fungus, not knowing what it was! You are giving me an advanced degree… You are terrific!
OMG! I have had this problem with my toenails for 3 years! I thought I had the pretty much incurable toenail fungus that so many people complain about and even went to my doctor and was given Lamisil to try and treat it. Lol It didn’t work. After reading this and seeing that my problem toenails looked strikingly similar to the pics in this post, I filed the top of my nails and I am happy to say the problem is gone! Even though I feel like an idiot, I’m so happy I saw this and realize I don’t have the more serious, almost incurable type of toenail fungus! Oh, and I learned my lesson about the dangers of nail polish. More people should know about this! Thanks 🙂