I developed ridges and grooves on my nails, as well as spaces under some of them, after I'd had Asian Flu when I was 17. I got all kinds of topical treatment from doctors who mostly thought it was a fungal condition. About ten years ago I bought a bottle of OPI Nail Envy and, to my astonishment, the spaces disappeared. More recently, a couple of nails have been peeling and splitting. I found a product that claimed to strengthen nails, called Nailtiques,Formula 2, Nail Protein. It worked well and, although I still have some ridges, I no longer need to wear coloured nail polish to hide the ugly mess they once were. I only wish it hadn't taken almost 60 years to sort out!