Allergic or bacterial pink eye (conjunctivitis)?

February 11, 2004

Yes. When a patient came for an allergy injection recently, she asked me if we had any samples of allergy eye drops she could have. She had been using over the counter eye drops, unsuccessfully, to relieve her symptoms.

I noticed that one eye was a deep consistent pink. The other eye appeared normal. I asked her if she had a discharge from her eye and she said it was matted shut in the mornings. During the day she often had thick purulent drainage from the eye. These symptoms had been present for several days, and she was starting to develop symptoms in the other eye as well. She had assumed it was caused by her allergies.

Instead of allergy eye drops, our physician prescribed an antibiotic eye drop. Her symptoms were consistent with bacterial conjunctivitis, or pink eye. After a couple of days of treatment with antibiotic eye drops, her symptoms were almost gone.

The over the counter eye drops may or may not have contributed to her conjunctivitis. But eye drops and tear-replacement products are listed as one of the causes of eye infections.

Eye drops can easily become contaminated with bacteria by touching the eye, fingertips, or any other substance, with the tip of the dropper. When the dropper is placed back in the bottle, bacteria begin to grow. Care should be taken to keep the dropper from touching anything, not even the eye.

Sometimes just opening and closing the bottle and having the dropper and liquid exposed to the atmosphere can allow droplets containing bacteria to contaminate the drops. Never use eye drops beyond the expiration date, or longer than the recommended "after-opening" time on the bottle.

Using over the counter drops can also delay needed prescribed treatment for conjunctivitis.

Often symptoms of pink eye caused by allergies and pink eye caused by bacteria are similar, but there may be subtle differences.

Usually allergic pink eye is seasonal, and it usually occurs in both eyes simultaneously. The drainage is usually clear, and it usually does not produce matting of the eye. Itching is very common in allergic pink eye. The redness may not be as pronounced in allergic pink eye as in bacterial pink eye.

Bacterial pink eye often begins in one eye and spreads to the other eye. It usually produces a thick yellow pus that drains from the affected eye, sometimes spilling out of the eye during the daytime and matting the eye shut at night. The pinkness or redness is often very deep in color. Eyes may feel scratchy, as if something is in them, but they usually do not itch.

Viral pink eye usually causes a more clear drainage than bacterial pink eye. Like bacterial pink eye, viral pink eye often occurs in one eye first. This is because bacterial and viral pink eye are often caused by direct contact with infected fingers.

Notice I used the word "usually" and "may" a lot. Sometimes even the physician cannot determine for sure which form of pink eye the patient has at first.

If you have pus draining from your eyes or your eyes are matted you should consult your physician. If your symptoms worsen or are not relieved within 24 hours, you should consult your physician. If your symptoms are accompanied by eye pain or sensitivity to light, you should consult your physician immediately. You may have a more serious eye disease requiring immediate treatment.

Never allow others to use towels or washcloths used by a person with pink eye. Always wash your hands carefully to avoid spreading the disease. Allergic conjunctivitis is not contagious, but viral conjunctivitis and bacterial conjunctivitis are highly contagious.

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