Vet at FirstVet answers:
If your dog is not showing any signs of squinting and is not trying to get to its eyes, you can try to treat them at home. Start by cleansing the eyes daily with saline to help remove the goo and then apply lubricating eye drops (purchased at your vets). If there is no improvement within a couple of days you should consult a veterinarian.
Please observe that it can be difficult to see the difference between an uncomplicated, superficial, irritation in the mucous membranes of the eyes and a deep inflammation of the eye (such as glaucoma, uveitis and corneal ulcers). If in doubt, you should always consult a veterinarian.