Conjunctivitis (Pink Eye)
Conjunctivitis is an inflammation of the conjunctiva, the mucous membrane that covers the front of the eye and lines the inside of the eyelids.
6 million.
10% of the population will experience conjunctivitis at some point in their lives.
Low.
Symptoms
What causes conjunctivitis?
Infectious conjunctivitis is almost always caused by viruses and bacteria.
Viral cases, comprising 70-80% of pink eye, are usually due to the adenovirus family, which also sometimes causes colds, bronchitis, and intestinal infections. Less commonly (in about 1-5% of cases), the herpes family of viruses can cause a more severe conjunctivitis.
Bacterial cases are predominantly caused by the same bacteria that can be involved with ear and sinus infections.
Also, newborns are vulnerable to a different subset of causative organisms in the first two weeks postpartum, which is the reason most babies receive antibiotic ointment on their eyelids shortly after birth.
How is it diagnosed?
Symptoms include pink or red eyes, sometimes with eyelid swelling; a gritty, painful, or itchy sensation; and ocular tearing or discharge. Diagnosing conjunctivitis is not typically difficult, though determining what caused it can be.
Bacterial cases tend to have thicker discharge that persists throughout the day and spontaneously re-accumulates after cleansing.
Viral cases are sometimes associated with cold symptoms, like sore throat or cough, and are more likely to cause enlarged lymph nodes. Other distinguishing features are of variable accuracy in studies.
What other conditions might be confused for pink eye?
Allergic conjunctivitis is the most common condition that may look similar. It can be seasonal and may be associated with other allergy symptoms.
Red eyes can also be caused by injury or irritation (corneal abrasion, chemical conjunctivitis, capillary hemorrhage, and dry eye) or by deeper inflammatory or infectious conditions (keratitis, iritis, scleritis, and acute angle closure glaucoma).
What are warning signs for a more serious infection or condition?
Moderate-to-severe eye pain, sensitivity to light (photophobia), and reduced visual acuity are findings that are not typically seen with conjunctivitis and could be a sign of a more serious condition that needs an urgent ophthalmology consultation.
Herpes and zoster (the virus that causes chickenpox and shingles) should be suspected in cases of decreased facial sensation or facial pain on the involved side; a rash on the same side or the tip of the nose is another indicator. These conditions benefit from rapid diagnosis and appropriate treatment.
Is there a test for conjunctivitis?
Most cases of conjunctivitis don't require testing, and are diagnosed by history alone. However, there are tests available for adenovirus, the most common cause of pink eye.
One of these, a point-of-care test, has good diagnostic specificity, but has not consistently demonstrated high sensitivity—studies have shown it detects about 50% of cases. Therefore, medical offices and hospitals have not adopted it into widespread use. There are other more accurate tests, but the usual result turnaround time of three-to-four days is not fast enough to influence most treatment decisions.
Treatment
What’s the best treatment?
As with colds—which are predominantly viral—antibiotics won’t work for viral conjunctivitis. Therefore, management is directed toward symptom relief and preventing transmission (more on that, shortly).
Bacterial will respond to antibiotics (which can help speed up recovery), but it's worth noting that these cases are usually self-limited, meaning they don’t always require medication. About 40% of them will self-resolve by days six-to-ten.
Antibiotics should be used in cases of severe bacterial infection—indicated by thick discharge and/or significant discomfort—and among those who wear contact lenses, have preexisting ocular surface disease, or are immunocompromised.
What’s the downside to prescribing antibiotic drops if the infection is viral?
Indiscriminate use of antibiotics can lead to the emergence of harder-to-treat antibiotic-resistant bacteria.
A portion of those who use antibiotic eye drops will have an adverse effect, or potentially spread the infection to an uninfected eye.
Also, antibiotic drops may provide a false sense of security when the cause viral. Since the medication is having no beneficial effect, the opportunity for the infection to spread due to carelessness increases.
If antibiotics don’t help for most cases, why are they so often prescribed?
Many of those policies are antiquated and don’t match with current medical recommendations. The American Association of Pediatrics (AAP) has updated their public-facing information to advise antibiotics only when medically appropriate and to discourage excluding children with conjunctivitis from activities. These recommendations have not been adopted unanimously, however, so some schools and facilities may still follow older policies.
What are the best ways to alleviate symptoms and/or hasten resolution when the cause is presumed to be viral?
Compresses—warm or cool, depending on patient preference—are commonly recommended as a way of cleaning the eye of discharge and providing comfort. Artificial tears or antihistamines can help manage the symptoms of itching or gritty sensation. None of these interventions impact duration of the infection.
Prevention
How can people avoid infections?
Frequent hand washing decreases risk significantly. Perhaps just as important is avoiding both touching the face and sharing towels with any infected close contacts.
Unfortunately, adenovirus is relatively resistant to disinfectants and can live on surfaces for weeks. 10% bleach solution has been found to be significantly more effective at destroying adenovirus than alcohol swabs, so ophthalmology office equipment disinfection recommendations reflect that.
Should contact lens wearers do anything differently?
Most of the time, conjunctivitis in people who wear contact lenses is still viral, which means there isn't much to do.
However, if the infection is bacterial, antibiotic eye drops are more important for contact lens wearers than non-wearers to prevent more invasive eye problems. Also, the bacteria strains involved may be different for contact lens wearers, so the medication choice is different.
With both viral and bacterial conjunctivitis, contact lenses that have been contaminated (worn just prior to or during the infection) should be disposed of, and glasses should be worn until the infection resolves.
Useful Links
When to use antibiotics for pink eye (Choosing Wisely)
What are the ophthalmology preferred practice patterns? (American Academy of Ophthalmology)
Connect with our physicians
Jamila Schwartz, MD and Andrew Cunningham, MD are both members of the Galileo Clinical Team. Connect with one of our physicians about Conjunctivitis (Pink Eye) or any of the many other conditions we treat.