Pink eye, medically known as conjunctivitis, is the inflammation of the conjunctiva, the thin, clear membrane covering the white part of the eye and the inner surface of the eyelids. Inflammation causes the tiny blood vessels to become more visible, giving the eye a characteristic pink or reddish appearance. While often contagious and uncomfortable, the condition is typically temporary and resolves completely. Understanding the different causes of conjunctivitis is important for distinguishing a common annoyance from a serious threat to vision.
Understanding Conjunctivitis
Conjunctivitis is a general term for inflammation, and its cause determines its severity and contagiousness. The three primary causes are viral, bacterial, and allergic.
Viral conjunctivitis is the most common form, often caused by adenoviruses responsible for the common cold. It is extremely contagious, produces a watery discharge, and typically clears on its own within two to three weeks without specific medication.
Bacterial conjunctivitis is less frequent and is characterized by a thicker, pus-like discharge that causes the eyelids to crust over, especially after sleeping. This contagious form may require antibiotic eye drops to speed recovery.
Allergic conjunctivitis is non-contagious and occurs when the eyes react to allergens like pollen or dust. Symptoms include intense itching and tearing in both eyes, often managed with cool compresses and antihistamine eye drops.
Assessing the Risk of Vision Loss
For the vast majority of cases, conjunctivitis is a self-limiting condition that resolves without causing lasting damage to the eye or vision. Typical viral and allergic forms do not affect the cornea, the clear outer layer responsible for focusing light. Permanent vision loss is an extremely rare outcome, associated almost exclusively with severe complications when the infection spreads beyond the conjunctiva.
The primary risk to vision comes from keratitis, which is inflammation of the cornea. If a severe bacterial infection or certain viruses penetrate the cornea, it can lead to scarring and permanent visual impairment. Aggressive forms of bacterial conjunctivitis, such as those caused by Neisseria gonorrhoeae or Chlamydia trachomatis, are particularly dangerous and can lead to rapid vision loss if not treated immediately. Corneal scarring from keratitis is the mechanism by which complications can affect the ability to see clearly.
When to Seek Immediate Medical Help
While most cases of pink eye are minor, certain “red flag” symptoms indicate the infection may have progressed to the cornea, requiring immediate medical evaluation. If the infection threatens vision, the symptoms will be significantly more intense than typical irritation.
You should seek urgent care if you experience severe eye pain, which is distinct from general scratchy irritation. Other major warning signs include sudden or progressive blurry vision, increased sensitivity to light (photophobia), or the feeling that something is lodged in the eye that cannot be flushed out. Additionally, seek care if symptoms worsen significantly after 24 to 48 hours rather than showing improvement. These symptoms suggest possible keratitis or a corneal ulcer, necessitating prompt intervention to prevent permanent damage.
Standard Treatment and Prevention
Management for common cases focuses on symptom relief and preventing the infection from spreading. Since viral conjunctivitis is the most common, treatment involves supportive care, such as using cold compresses to soothe inflammation and artificial tears to lubricate the eye surface. Antibiotic eye drops are reserved for confirmed bacterial infections and are ineffective against viral causes.
Preventing transmission is crucial for contagious viral and bacterial types. This involves meticulous hygiene, including frequent handwashing and avoiding touching the eyes. Infected individuals should use separate towels and pillowcases and avoid sharing personal items, such as eye makeup. Contact lens wearers must immediately stop using their lenses at the first sign of symptoms and follow professional instructions regarding cleaning or discarding the lenses and case.