Green eye droppings in one eye of a dog may be caused by improper diet, foreign matter in the eye, or not paying attention to hygiene. You need to clean up the eye secretions in time, and then put some anti-inflammatory eye drops on it. Feed the dog some light food and observe it for two days to see if it improves. If not, it is best to take the dog to the pet hospital for examination and treatment to avoid aggravation of the condition.