Fatty eye ( or sometimes called ‘Pea-eye’) is a genetic condition in guinea pigs.
It causes the permanent protrusion of the ‘pink’ area of the eye (called the mucosa or conjunctival sac) to become enlarged and eyes look droopy.
This is usually a slow process and takes place over a couple of years and is usually only first noticed around 2 years of age.
It is also found in piggies with a heart condition, so if your piggie is showing signs of not moving around as much, or unusual behaviour in anyway, it is worthwhile to have this checked by an exotic vet.
Commonly piggies don’t notice this and it doesn’t cause any pain or discomfort. They can live happily with this.