Pink eye is an inflammation of the transparent membrane that lines the eyelid and eyeball. This membrane is called the conjunctiva. When small blood vessels in the conjunctiva become swollen and irritated, they’re more visible. This is what causes the whites of the eyes to appear reddish or pink. Pink eye also is called conjunctivitis.
Pink eye is most often caused by a viral infection. It also can be caused by a bacterial infection, an allergic reaction or — in babies — an incompletely opened tear duct.Though pink eye can be irritating, it rarely affects your vision. Treatments can help ease the discomfort of pink eye. Because pink eye can be contagious, getting an early diagnosis and taking certain precautions can help limit its spread.
There are serious eye conditions that can cause eye redness. These conditions may cause eye pain, a feeling that something is stuck in your eye, blurred vision and light sensitivity. If you experience these symptoms, seek urgent care.
People who wear contact lenses need to stop wearing their contacts as soon as pink eye symptoms begin. If your symptoms don’t start to get better within 12 to 24 hours, make an appointment with your eye doctor to make sure you don’t have a more serious eye infection related to contact lens use.
Most cases of pink eye are caused by adenovirus but also can be caused by other viruses, including herpes simplex virus and varicella-zoster virus.
Both viral and bacterial conjunctivitis can occur along with colds or symptoms of a respiratory infection, such as a sore throat. Wearing contact lenses that aren’t cleaned properly or aren’t your own can cause bacterial conjunctivitis.
Both types are very contagious. They are spread through direct or indirect contact with the liquid that drains from the eye of someone who’s infected. One or both eyes may be affected.
Allergic conjunctivitis affects both eyes and is a response to an allergy-causing substance such as pollen. In response to allergens, your body produces an antibody called immunoglobulin E (IgE). IgE triggers special cells in the mucous lining of your eyes and airways to release inflammatory substances, including histamines. Your body’s release of histamine can produce a number of allergy symptoms, including red or pink eyes.
If you have allergic conjunctivitis, you may experience intense itching, tearing and inflammation of the eyes — as well as sneezing and watery nasal discharge. Most allergic conjunctivitis can be controlled with allergy eye drops. Allergic conjunctivitis is not contagious.