What causes pink eye in adults

What is Pink Eye (Conjunctivitis)?

Pink eye, medically known as conjunctivitis, is a common condition characterized by inflammation of the conjunctiva. The conjunctiva is a thin, transparent membrane that lines the inner surface of the eyelids and covers the white outer surface of the eyeball. When the conjunctiva becomes inflamed or infected, it can cause the white part of the eye to appear reddish or pink, hence the common name "pink eye." This inflammation can lead to a range of symptoms, including redness, itching, burning, a gritty sensation, and discharge from the eye.

Common Causes of Pink Eye in Adults

The causes of pink eye in adults are diverse, ranging from infectious agents to environmental factors and underlying health conditions. Understanding these causes is crucial for effective treatment and prevention.

Infectious Conjunctivitis

Infectious conjunctivitis is further divided into viral and bacterial forms, both of which are highly contagious.

Viral Conjunctivitis

Viruses are the most common culprit behind pink eye, particularly in adults. Often, viral conjunctivitis occurs alongside other viral illnesses, such as the common cold or flu. Adenoviruses are frequently responsible, but other viruses like herpes simplex virus and varicella-zoster virus can also cause it. Symptoms typically include watery discharge, redness, and a feeling of grittiness. It often starts in one eye and can spread to the other. Viral conjunctivitis usually resolves on its own within one to three weeks without specific medical treatment, though supportive care can alleviate symptoms.

Bacterial Conjunctivitis

Bacterial conjunctivitis is caused by bacteria such as Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae, and Chlamydia trachomatis. This form of pink eye often produces a thicker, pus-like discharge (often described as yellow or green) that can cause the eyelids to stick together, especially after sleeping. It can affect one or both eyes. While some cases may resolve spontaneously, bacterial conjunctivitis typically requires antibiotic eye drops or ointments prescribed by a healthcare professional to clear the infection and prevent complications.

Allergic Conjunctivitis

Allergic conjunctivitis is not contagious and occurs when the eyes react to an allergen. Common allergens include pollen, dust mites, pet dander, mold spores, and certain eye drops or contact lens solutions. The immune system releases histamine and other chemicals in response to these allergens, leading to inflammation. Symptoms usually include intense itching, redness, tearing, and swelling of the eyelids. It characteristically affects both eyes simultaneously. Unlike infectious conjunctivitis, allergic pink eye is managed by avoiding allergens and using antihistamine eye drops or oral medications.

Irritant Conjunctivitis

Exposure to irritants can also cause inflammation of the conjunctiva. These irritants can be environmental, such as smoke, smog, chlorine from swimming pools, or dust. They can also be chemical, like shampoo getting into the eyes or exposure to harsh cleaning products. The body's response is to flush out the irritant, leading to redness and watering. Symptoms are usually mild and resolve once the irritant is removed. If symptoms persist or are severe, medical attention may be needed.

Other Causes

Contact Lens-Related Conjunctivitis

Improper contact lens hygiene is a significant cause of conjunctivitis in contact lens wearers. This can include overwearing lenses, sleeping in lenses not approved for overnight wear, or inadequate cleaning and disinfection of lenses and cases. This can lead to bacterial infections, allergic reactions to lens solutions, or a condition known as giant papillary conjunctivitis (GPC), where small bumps form under the eyelid, causing irritation and discharge.

Fungal and Parasitic Conjunctivitis

Less commonly, fungal or parasitic infections can cause conjunctivitis. Fungal infections are more likely in individuals with weakened immune systems or following an injury involving plant matter. Parasitic infections are rare in developed countries but can occur from contaminated water or soil.

Underlying Health Conditions

In some instances, conjunctivitis can be a symptom of a more systemic health issue. For example, certain autoimmune diseases like rheumatoid arthritis or Sjögren's syndrome can affect the eyes. Additionally, conjunctivitis can sometimes be associated with sexually transmitted infections like gonorrhea and chlamydia, particularly in newborns but also possible in adults.

When to See a Doctor

While many cases of pink eye resolve on their own or with simple home care, it's important to seek medical advice if you experience any of the following:

• Severe eye pain
• Vision changes, such as blurred vision or increased sensitivity to light
• Symptoms that worsen or don't improve after a few days of home care
• A weakened immune system (due to illness or medication)
• Symptoms suggesting a more serious condition, like a corneal ulcer
• Thick, pus-like discharge that prevents you from opening your eye

Prompt diagnosis and appropriate treatment are essential to prevent potential complications and ensure a speedy recovery.