What is the build up around guinea pigs eyes?

Crusty eyes (a sign of a bacterial infection)

Bulging eyes (infection, injury, or tooth root problem)

Sunken eyes (may be a sign of dehydration)

Cloudy eyes (treat eye injuries promptly to prevent eye loss)

NOTE: Some guinea pigs develop a condition called "pea eye" in which the white conjunctiva is visible. Seek treatment if there is tearing, crustiness or redness (inflammation).