OKay, I'm no doctor,nor did I stay at a Holiday Inn Express last night, but here is what Wikipedia has to say.....
[edit] Symptoms
Eyes with conjunctivitisRedness, irritation and watering of the eyes are symptoms common to all forms of conjunctivitis. Itch and the closing of the throat is variable.
Acute allergic conjunctivitis is typically itchy. Sometimes distressingly so, and the patient often complains of some lid swelling. Chronic allergy often causes just itch or irritation, and often much frustration because the absence of redness or discharge can lead to accusations of hypochondria.
Viral conjunctivitis is often associated with an infection of the upper respiratory tract, a common cold, and/or a sore throat. Its symptoms include watery discharge and variable itch. The infection usually begins with one eye, but may spread easily to the fellow eye.
Bacterial conjunctivitis due to the common pyogenic (pus-producing) bacteria causes marked grittiness/irritation and a stringy, opaque, grey or yellowish mucopurulent discharge (gowl, goop, "gunk", "eye crust", sleep, or other regional names) that may cause the lids to stick together (matting), especially after sleeping. Another symptom that could be caused by Bacterial Conjunctivitis is severe crusting of the infected eye and the surrounding skin. However discharge is not essential to the diagnosis, contrary to popular belief. Many other bacteria (e.g., Chlamydia, Moraxella) can cause a non-exudative but very persistent conjunctivitis without much redness. The gritty and/or scratchy feeling is sometimes localised enough for patients to insist they must have a foreign body in the eye. The more acute pyogenic infections can be painful. Like viral conjunctivitis, it usually affects only one eye but may spread easily to the other eye. However, it is dormant in the eye for three days until patient shows signs of symptoms.
Irritant or toxic conjunctivitis is irritable or painful when the infected eye is pointed far down or far up. Discharge and itch are usually absent. This is the only group in which severe pain may occur.