Conjunctivitis is a medical term for inflammation of the inside of the eyelids and the front part of the eye.  Viruses are responsible for the majority of eye infections and bacterial infections occur less commonly.  Most eye infections resolve without treatment.  Bacterial infections may require antibiotic eye drops.  Eye redness may be caused by other non-infectious causes such as allergies, eye trauma, foreign bodies, or chemical irritation.  Tear duct blockage is a common cause of excessive tears and eye discharge in an infant.

What causes eye infections?

In neonates:

• Chlamydia trachomatis (transmitted by the mother at birth)
• Neisseria gonorrhoeae  (transmitted by the mother at birth)
• Staphylococcus aureus

Bacterial:

• Haemophilus influenzae
• Streptococcus pneumoniae
• Staphylococcus aureus
• Pseudomonas

Viral:

• Adenovirus
• ECHO virus
• Coxsackievirus
• Herpes Simplex

What non-infectious things can look like an eye infection?

Allergic - eye itching, eye redness, eyelid swelling, and excessive eye watering are the major symptoms.  Yellow eye discharge (pus) is usually absent or mild.  Significant eye itching may help diagnosis an allergic cause.

Eye trauma - eye pain and discomfort may be severe.  Redness, eyelid swelling, sensitivity to light and excess eye watering are also common.

Foreign body - children often will tell you "something is in my eye."  Symptoms may be worse with eye movement.

Chemical irritation - smoke and chemical fumes may cause eye redness and excessive eye watering.  Eye medicines can cause irritation in some children.  Even antibiotic eye drops used to treat a possible eye infection can cause worsening redness and irritation in the eyes.

Eyelid swelling - swelling of the eyelids may be the first sign of kidney or other fluid balance problems.

Glaucoma - increased pressure within the eyeball.

How is an eye infection diagnosed?

Usually the symptoms make diagnosis easy.  A sample of the eye discharge may be cultured to determine if the cause is bacterial, although this is usually not necessary.

How is eye trauma or a corneal abrasion diagnosed?

Often the child remembers something contacting the eye or having a sensation of something stuck in the eye.  A physician can use flouroscein dye in the affected eye along with an ultraviolet light to look for a scratch on the eyeball surface (example - corneal abrasion).

How is an eye infection treated?

Most cases of viral conjunctivitis will resolve within a few days without treatment.  If a bacterial eye infection is suspected, antibiotic eyedrops are often used for 7-10 days.

 Photo - Conjunctivitis.  CDC/Joe Miller 1976.  Used with permission.