Conjunctivitis is an inflammation of the membranes that line the eyelid or the eye. When the condition occurs in babies younger than 4 weeks old, it is called neonatal conjunctivitis.

What is going on in the body?

The conjunctiva is a mucous membrane that forms the outermost layer of the eye. Any type of irritation to the eye can cause the blood vessels in the conjunctiva to enlarge. This makes the eye appear red. Irritation also causes the eye to produce more tears. When the eye is infected, white blood cells and mucus are seen on the conjunctiva. This appears as a thick, yellow-green discharge from the eye.

What are the causes and risks of the disease?

Conjunctivitis in newborns is often caused by bacteria acquired during birth. The baby gets the bacteria from the mother's vagina during delivery. These bacteria often come from a sexually transmitted disease, or STD. An infant can also be infected if his or her eyes are touched by contaminated hands or objects.

Conjunctivitis caused by gonorrhea used to be the leading cause of blindness. It shows up at birth or within the first week afterward. In 1981, healthcare providers began putting silver nitrate in the eyes of newborns. This prevents the infection.

The bacteria that cause chlamydia, an STD, also cause conjunctivitis in newborns. About half of infants born to infected mothers get the eye infection. Symptoms from this type of the disease show up several days to weeks after birth.

A rare cause of conjunctivitis is the Pseudomonas aeruginosa bacterium. Since it is generally found in hospital settings, newborns and hospitalized people are more at risk. The bacteria can get into the infant's bloodstream. From there, the infection can travel throughout the body. The result can be shock and death.

Staphylococcus and other bacteria can sometimes cause neonatal conjunctivitis. These infections are similar to those caused by chlamydia.