In fact, it is really difficult to tell bacterial and viral keratitis for a common people. Easily speaking, we can tell both of them by the reason why your eyes have the keratitis. That is to say, your keratitis can be caused by both the bacterial and viral, and however, when you go to see doctor, the doctors often give you some antibacterial. Of course, apart from the reason, you can also get your answer by the sign of the two diseases. As usual, when you get the bacterial keratitis, your eyes often are getting red and also you always want to rub your eyes. In the mean time, you will notice that you both of your eyes will get affected. However, when you get the viral keratitis, usually, only one of your eyes will affect. And of course, you will find that the viral keratitis will cause excessive eye watering, sometimes, you also can notice your eyes have light discharge. In a word, no matter what kind of the keratitis you get, you should ask for help from your doctor because he will help you tell them and give you some useful pills.
There is the difference between the bacterial and viral keratitis. When the violation of pathogenic bacteria is more than the host defense function or host defense function damage, such as dry eyes, long-term use of corticosteroids and so on, it can cause the eye conjunctival inflammation and purulent seepage which should be suspected bacterial conjunctivitis. Usually the bacterial conjunctivities could be cured for about a week by using the eye drops with anti-inflammation role. And the viral conjunctivitis will have 5 ~ 12 days after the incubation period of symptoms, including conjunctival congestion, watery discharge, eye stimulation, waking up eyelid and sticking eyes symptoms. It usually starts at many patients with contact conjunctivitis. Suffering from respiratory infections bulbar conjunctiva and palpebral conjunctiva congestion, the palpebral conjunctiva appear conjunctival follicle. It could be treated for more than a week by killing the bacterium and infection in the eyes. In a word, their causing reason is different and their symptom on the eyes problems is different too. And their treatment time is different too.
Well, it seems that you would like to distinguish between two of them. Anyway, as far as I know, both of them are quite serious diseases and would give rise to a lot of symptoms, leading to some terrible consequences if not properly treated. Generally speaking, bacterial keratitis would generate more eye discharge, while virus one does not. Anyway, you should consult a doctor and take an eye exam then tackle the problem.