Which feature helps differentiate bacterial conjunctivitis from viral conjunctivitis?

• A. Purulent or mucopurulent discharge with eyelid crusting
• B. Watery discharge
• C. Itchy eyes with watery discharge
• D. Photophobia

Answer: (A)

Discharge quality is the key clue when telling bacterial from viral conjunctivitis. Bacterial infections tend to produce thick, purulent or mucopurulent discharge that sticks to lashes and crusts the eyelids, especially after sleep. This crusting reflects pus-forming bacteria and remains a hallmark of bacterial conjunctivitis. Viral conjunctivitis, on the other hand, usually has watery to mucoid discharge and is often accompanied by a concurrent upper respiratory infection; the discharge isn’t the thick pus with crusts seen in bacterial cases. Itchy eyes with watery discharge points more toward allergic conjunctivitis, while photophobia can occur with corneal involvement and isn’t specific to bacterial versus viral forms. So, the presence of purulent or mucopurulent discharge with eyelid crusting best differentiates bacterial from viral conjunctivitis.