I have used this type for many years now. Before each swim I wash with a little Fairy Liquid and rinse, then wet with clean water before putting them on. I have just completed a 5k swim and they remained crystal clear throughout. I always have a spare pair of a different colour (so I know which is which!)because after a couple of years they will start to leak (not unreasonable!), and I don't want to be caught out at an event.