Dear Doctors: My granddaughter got pink eye right before our family reunion. I worried everyone was going to wind up getting it. The doctor said because it was bacterial, antibiotic drops would help clear it up fast. Is bacterial pink eye very different from viral? Aren't they both contagious?
Dear Reader: Although most people have heard of pink eye, many don't realize that the familiar infection can have more than just one cause. Depending on which kind of pathogen is involved, medication may help clear the infection, or the person may simply have to ride it out.
For those fortunate enough to have no personal experience with it, pink eye is an inflammation of the conjunctiva. That's the thin, clear membrane that covers the white portion of the eye and lines the inner surface of the eyelid. The conjunctiva helps shield the delicate tissues of the eye from potential irritants and pathogens. It also contributes to the tears and mucus that keep the exposed surfaces of the eye from drying out. A dense network of threadlike capillaries delivers oxygen and nutrients to the conjunctiva. It also plays host to tiny lymphatic vessels, which are involved in immune response.
If the conjunctiva becomes infected by either a bacterium or a virus, the resulting inflammation is known as conjunctivitis. When this occurs, the immune system roars into action. It uses that network of capillaries in the conjunctiva to deliver nutrients and immune cells to the surrounding tissues. This leads to irritation and inflammation that cause the distinctive pink or red color. At the same time, the lymphatic vessels collect and drain away excess fluid and cellular waste.
Bacterial and viral conjunctivitis share many symptoms. These include red, swollen, itchy and weepy eyes. However, there is an important difference between the two: When pink eye is caused by bacteria, antibiotic eyedrops can be used. These can often help clear the infection and thus speed recovery. Unfortunately, the same is not true of a viral infection. When a virus is the cause, you have to wait while the immune system does its job. This typically takes one to two weeks, although some infections last longer.
You are correct that viral and bacterial pink eye are each quite contagious. If someone touches their own eye after coming into contact with the contaminated fluid or discharge from an infected person's eye, they can transfer the bacterium or virus. When someone with an active case of conjunctivitis coughs or sneezes, the tiny droplets they release can reach another person's eye and cause an infection. Pink eye can also be caused by debris in the eye or an allergy. In those cases, the condition is not contagious.
To protect yourself from pink eye, focus on hygiene. Wash your hands before touching your eye. Personal items, such as makeup, washcloths or eyeglasses should not be shared. Any eye drops or solutions used during an infection must be thrown away. If symptoms persist or include pain, sensitivity to light or blurred vision, please seek medical care.
(Send your questions to [email protected], or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)
