Updated December 15, 2014.
When most parents think of pink eye (conjunctivitis), they are thinking of a bacterial infection of the eye. There are a lot of causes of red eyes though, including viral infections, allergies and irritation.

Symptoms

When caused by a bacteria, children with pink eye will have green or yellow discharge from their eyes and the white parts of their eye and the inside of the lower eyelid will be red. In addition to being matted when they wake up, with bacterial conjunctivitis, you will have to frequently wipe away the drainage from your child's eyes.
In addition to bacterial infections, children can have pink eye from allergies (allergic conjunctivitis), which will cause their eyes to be red, itchy, and tearing.

Viral infections can also cause pink eye. In addition to being intensely red, children with a virus that causes pink eye will have tearing and a white discharge.

A scratched eye or corneal abrasion can also cause tearing, redness and pain in a child's eye. While most infections affect both eyes, an abrasion would be expected to just cause symptoms in one eye.

Diagnosis

Although cultures can be done, the cause of pink eye is usually diagnosed by a physical examination and the pattern of symptoms.

Treatments

Bacterial causes of pink eye require an antibiotic, either topical drops or ointments or an oral antibiotic if your child has another bacterial infection (like an ear infection).
Allergic conjunctivitis can be treated with typical allergy medications, and topical drops, like Patanol and Alocril.

Viral causes of pink eye do not usually require treatment.

Pink eye can also be caused by irritants, like smoke and dust.

Whatever the cause, you should usually wipe away any eye discharge with a warm moist cloth and wash your hands frequently in case it is contagious.

Over the counter can also often help with the redness and irritation in older children.

What You Need To Know

• pink eye is probably overdiagnosed. With an upper respiratory tract infection, many children have reflux of their nasal drainage through their tear ducts and into their eye. These kids will usually have a runny nose and cough and a little drainage from their eyes, especially when they wake up. They will not have continuous eye drainage throughout the day and their eyes will not be red. This pattern of eye drainage is usually not pink eye and doesn't require treatment.
• for bacterial infections, eye ointments are typically used for younger infants, while older children usually do better with eye drops.
• unless caused by an allergy or irritation, most causes of pinkeye are contagious.
• if your child with pink eye doesn't respond to typical treatments, or if he also complains of pain or vision problems, an evaluation by a Pediatric Ophthalmologist might be a good idea.