When I had my Lab Joe, he got them quite a bit when he was younger and digging constantly. I had a bottle of saline and washed his eyes out everytime I saw him digging, and it helped, but he still got a lot of them. His rheumatoid arthritis put an end to his digging. I guess even a crippling disease has a benefit.
Right now, King and Molly both are just getting over eye infections. King's came up suddenly. I noticed nothing when I looked at him before I went to bed, and 8 hours later, his left eye was glued shut. I took them both to the vet, since they had shots due anyway. Her eyes got all snotty the next morning, of course. The vet did exactly what I expected, put the green stuff in his eyes to check for scratches, etc, and then, because he's getting close to 11, checked his eye pressure, which was great. My wallet spasmed, as usual. Just when I got the vet paid off, of course.