Tell the Difference Between Bacterial & Viral Conjunctivitis - Check both eyes. Bacterial conjunctivitis often spreads to both eyes, while viral conjunctivitis often only affects one eye, according to AllAboutVision.com. With strict hygiene (and no touching of the affected eye), the spread of the viral type of conjunctivitis can be easily prevented.
Evaluate the discharge. Bacterial conjunctivitis has a heavier discharge than viral conjunctivitis. When the eye is experiencing a bacterial infection, the discharge is often thick and greenish in color, according to AllAboutVision.com. Viral conjunctivitis is characterized by excessive watering, rather than heavy discharge.