I just found a virtually invisible hair splinter on the palm of my hand using a jeweller's loupe. It's been bothering me for days but I couldn't see it. Within a minute of using the loupe I had located and removed it as well as a few stubborn ingrowing hairs I'd been stalking.
Deffo worth the investment of a few quid, but use with care. I could easily have lost a few hours examining myself.