Thanks PP . I leave mine on overnight but someone told me you shouldn't as it really impairs their vision ? So wasn't sure if I should start taking it off .
I used to religiously take them off but I have found this year the flies are quite bad late in the evening and early in the morning so I leave them on, and just check that they're not rubbing anything. They seem fine with it.
Exactly what skint1 says! Very late in the evening I have seen flies glued round my ponies eyes, I leave them on and check in the morning. I'm not sure about their vision, never really thought about that!