If there is clear, watery discharge from the eye, the chinchilla may have gotten dust or some other foreign material in it. Remove the dust bath for a week, and see whether the condition improves. Watery discharge can also be a sign of corneal abrasion or ulcer, a scratch on the surface of the eye. A vet can put fluoricine dye in the eye and use a fluorescent lamp to see the ulcer. The usual treatment is antibiotic eye ointment. I have also noticed that one of my chinnies gets watery eyes if I'm a day or two late changing the cage. Some chins may be more sensitive to products of urine breakdown, such as ammonia. In this case, change the cage more often, and see whether your chin's eye gets better. If there is opaque white or yellow discharge from the eye, this most likely indicates an infection. Take the chinchilla to a vet, who can diagnose the cause and give you the proper antibiotic ointment.