A guinea pigs’ eyes should be bright and shiny. If they're not, there is an underlying problem.
Discharge builds up naturally in the corners of a guinea pig's eyes - just like any other mammal - and the GP will remove this with its paws. However, if you notice that the eyes are crusty, cloudy, protruding or ulcerated, there is a health problem that needs addressing. For example, crusty eyes and a runny nose indicates a respiratory infection or allergy. In these circumstances a trip to the vet is needed.
A healthy Guinea pigs' eyes are shiny and bright
If your guinea pig's eyes need cleaning, and yet they don’t seem able to do it themselves, this too may indicate a health problem. Ask your vet for advice.