Conjunctivitis
OVERVIEW
- Symptoms:
Pink or red eyes, itchy or burning eyes, watery eyes, unusual fluid (discharge) coming from the eyes
- Diagnosis:
Eye exam, lab tests
- Treatment:
Medicine (eye drops or ointment)
CAUSES
Most of the time, pink eye is caused by an infection — a virus or bacteria. Viral pink eye is the most common type. Pink eye that’s caused by an infection can spread very easily, so avoid passing it to others by washing your hands often and not sharing items like pillowcases, towels, or makeup.
You can also get pink eye from an allergy or eye irritation.
Viral pink eye is most often caused by a common virus called adenovirus, but other viruses can also cause pink eye. If you have viral pink eye, you may also have a cold or sore throat.
Bacterial pink eye can be caused by many different types of bacteria. Some common types are Staphylococcus aureus, Streptococcus pneumoniae, or Haemophilus influenzae.
It’s also possible to get pink eye from a fungus or parasite, but it’s not common.
SYMPTOMS
- Pink or red eyes
- Itchy or burning eyes
- Watery eyes
- White, yellow, or green fluid (discharge) coming from your eyes
- Crust along your eyelids or eyelashes, which may keep your eyes from opening when you wake up
- Swollen eyelids
- A feeling like something’s stuck in your eye
- Sensitivity to bright light
- Blurry vision
- A lump in front of your ear
If you wear contact lenses, you may notice that they feel uncomfortable or don’t stay in place.
TYPES
Bacterial Conjunctivitis
Although more rare, bacterial infections can also cause conjunctivitis. Types of bacteria that cause pink eye include:
- Staphylococcus aureus
- Streptococcus pneumoniae
- Haemophilus influenzae
- Moraxella catarrhalis
- Chlamydia trachomatis
- Neisseria gonorrhoeae
Bacterial conjunctivitis also spreads easily by touch, either through hand-to-eye contact or hand-to-nose contact. It can also thread through improper contact lens use.
According to the Centers for Disease Control (CDC) and Prevention, this type of pink eye is more common in adults than kids and occurs most frequently during the winter months (November through February).
Viral Conjunctivitis
Viral infections cause nearly 80% of all conjunctivitis cases. Many different viruses, such as adenovirus, which typically leads to the common cold, can be the source of infection. Viral conjunctivitis spreads easily via touch from person to person, making outbreaks common among children in schools or daycare centers.
Allergic Conjunctivitis
Allergic reactions occur when your body responds abnormally to an allergen that is otherwise harmless. In this case, mast cells in your eye recognize allergens as foreign invaders and release a chemical called histamine as a defense mechanism. In turn, the histamine causes inflammation and swelling that leave your eyes red, teary, and itchy.
Allergens that cause a runny nose or sneezing can also affect your eyes. These allergens include pollen, dust, pet dander, mold, or smoke. Certain types of perfume, skin care or eye care products, or medications can also trigger eye allergies. For example, some over-the-counter or prescription eye drops have preservative chemicals that can cause allergic reactions.
