Like Betsy has said piggies tend to produce a milky looking cleaning fluid from their eyes. They wipe it away themselves but occasionally you will catch sight of it before they do. How long have you had your piggy and has their eye changed at all? Is is watery constantly? If there has been any sudden change then it is always worth a health check at the vets as it is impossible for us to diagnose a piggy. One, we aren't trained. Two, its just a photo and we haven't had a chance to handle and inspect the piggy