Are you sure it is an infection and not hay poke (a bit of hay getting into the eye and scratching the eyeball)? Or possibly even just a blocked tear duct?
From the photograph you have added the eyeball itself looks okay from what I can see, but the eye is watery and squinted. Usually that is more indicative of a blocked tear duct, or minor hay poke.
Lift up the eyelids and check for any bits of hay trapped between the eyelid and eyeball. If there isn't any hay in the eye then take a cloth with a bit of warm water and massage the inner corner of the eye, this will help if it is a blocked tear duct. You can use the saline drops as long as they are sterile drops meant for use on eyes.