Conjunctivitis, commonly known as pink eye, is the inflammation of the conjunctiva, the thin membrane covering the white part of the eye and the inner surface of the eyelids. Allergic conjunctivitis (AC) is considered a form of pink eye because it causes this inflammation and redness. The crucial distinction is that AC is an immune response to an allergen, such as pollen or pet dander, and is not contagious.
The Different Categories of Conjunctivitis
The various forms of conjunctivitis are classified based on their underlying cause, which dictates the appropriate treatment and the risk of spreading. The largest group falls under infectious conjunctivitis, primarily caused by viruses, with adenovirus being a common culprit. Viral conjunctivitis is highly contagious and frequently occurs alongside symptoms of an upper respiratory infection, like a common cold.
Bacterial conjunctivitis, while less common than the viral form, is also contagious and is caused by bacteria, often from the person’s own skin or respiratory system. The third major category is allergic conjunctivitis, which is not caused by an infectious agent but by the body’s immune system overreacting to a harmless substance.
How to Distinguish Allergic from Infectious Pink Eye
The most telling symptom of allergic conjunctivitis is intense itching. Allergic forms typically affect both eyes simultaneously, as exposure to airborne allergens like pollen is rarely limited to one eye. In contrast, infectious forms often begin in just one eye before possibly spreading to the other after a day or two.
The discharge also differs significantly: allergic pink eye produces a clear, watery or sometimes stringy, white discharge. Bacterial conjunctivitis is known for a thick, pus-like discharge that is yellow or green and can cause the eyelids to stick together, especially upon waking. Viral pink eye usually features a watery discharge, similar to allergies, but often includes a gritty or foreign body sensation. Allergic conjunctivitis is frequently accompanied by other symptoms, such as sneezing, nasal congestion, or a runny nose. Infectious cases, especially viral ones, may follow a cold, sore throat, or ear infection.
Practical Management and Relief Strategies
Management focuses on reducing exposure to the triggering allergen and providing symptomatic relief. A primary strategy is avoidance, which may involve keeping windows closed during high pollen seasons and using air purifiers with High-Efficiency Particulate Air (HEPA) filters indoors. Frequent hand washing and avoiding rubbing the eyes are also important, as rubbing physically worsens symptoms.
Non-medicated relief often starts with applying a cold compress to the closed eyelids, which helps reduce swelling and inflammation. Using preservative-free artificial tears is also helpful, as these drops can physically wash allergens and inflammatory substances from the eye’s surface.
For over-the-counter treatment, combination eye drops containing both an antihistamine and a mast cell stabilizer are highly effective. The antihistamine component, such as ketotifen, blocks the immediate effects of histamine to relieve itching quickly. The mast cell stabilizer works by preventing mast cells from releasing inflammatory chemicals, helping to control future symptoms. In cases of chronic or severe allergic conjunctivitis, a healthcare provider may prescribe stronger topical medications, including non-steroidal anti-inflammatory drugs (NSAIDs) or corticosteroids.
Warning Signs That Require Immediate Care
Certain symptoms suggest a severe issue that requires professional evaluation. Any sudden or noticeable change in vision, such as blurring, should prompt an immediate visit to a doctor. Intense eye pain that goes beyond irritation or itching is a serious red flag, as this can signal a complication like corneal involvement.
Extreme sensitivity to light, known as photophobia, can also indicate a more severe condition. If the redness, discharge, or discomfort worsens rapidly or fails to improve after 24 to 48 hours of treatment, medical attention is warranted. Contact lens wearers should immediately remove their lenses at the first sign of redness and seek care, as they are at a higher risk for serious corneal infections.