Fatty eye is a genetic condition in guinea pigs. It makes the ‘pink’ area of the eye ( called the mucosa) become enlarged and eyes look droopy. This is usually a slow process and takes place over a couple of years.
It is also found in piggies with a heart condition, so if your piggie has laboured breathing, or is not wanting to move about much, it will be worth checking this out.
There have been cases where vets have rectified this droopy look surgically, but this option is extremely dangerous to the piggie as with any anaesthetic. Fatty eye will not harm the piggie in any way and it does not affect their eye sight.