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Inflammation of the Eye (Conjunctivitis)

What is Inflammation of the Eye (Conjunctivitis)?

Conjunctivitis, commonly called “pink eye,” is the inflammation of the conjunctiva – the thin, transparent membrane that lines the inside of the eyelids and covers the white part of the eye (the sclera). When inflamed, the conjunctiva becomes red, swollen, and may produce a watery or purulent discharge. The condition is usually benign and self‑limiting, but it can be highly contagious when caused by infectious agents, and in some cases it signals a more serious eye problem.

There are three primary categories of conjunctivitis:

• Viral conjunctivitis – most often caused by adenoviruses; typically spreads through hand‑to‑eye contact.
• Bacterial conjunctivitis – caused by common bacteria such as Staphylococcus aureus, Streptococcus pneumoniae, or Haemophilus influenzae.
• Allergic conjunctivitis – a reaction to pollen, animal dander, dust mites, or chemicals.

Less common forms include chemical or irritant conjunctivitis (from smoke, chlorine, or cosmetics) and neonatal conjunctivitis (often due to Chlamydia trachomatis or Neisseria gonorrhoeae). Understanding the type is essential for selecting the right treatment.

Common Causes

Conjunctivitis can arise from many different sources. Below are the most frequent triggers, grouped by category.

• Viruses – adenovirus (most common), herpes simplex virus, enteroviruses, and, rarely, the measles or varicella‑zoster virus.
• Bacteria – S. aureus, S. pneumoniae, H. influenzae, M. catarrhalis, and in newborns, C. trachomatis or N. gonorrhoeae.
• Allergens – pollen, animal dander, mold spores, dust mites, latex, or eye‑makeup preservatives.
• Irritants & chemicals – chlorine from swimming pools, smoke, cleaning agents, air‑freshener sprays, or accidental splashes of acids/bases.
• Contact lens misuse – prolonged wear, poor hygiene, or contaminated lens solution.
• Foreign bodies – tiny particles (e.g., sand, eyelash) that can physically irritate the conjunctiva.
• Systemic diseases – autoimmune conditions such as rheumatoid arthritis, Sjögren’s syndrome, or inflammatory bowel disease may cause a chronic, painless conjunctivitis.
• Medication toxicity – certain eye drops (e.g., prostaglandin analogs for glaucoma) can induce a mild inflammatory response.
• Neonatal exposure – infection acquired during birth from an infected mother’s genital tract.
• COVID‑19 – recent studies have documented a higher incidence of viral conjunctivitis in patients with SARS‑CoV‑2 infection (CDC).

Associated Symptoms

While the hallmark of conjunctivitis is a red eye, other symptoms often accompany the inflammation, varying with the cause.

• Eye discharge – watery for viral/allergic types, thick yellow/green for bacterial.
• Itching or burning sensation – most intense with allergic conjunctivitis.
• Feeling of a foreign body or gritty sensation.
• Swelling of the eyelids or conjunctiva (chemosis).
• Light sensitivity (photophobia) – more common when the cornea is involved.
• Blurry vision – usually temporary, caused by excess tearing or discharge.
• Tearing and excessive watering.
• Fever, sore throat, or upper‑respiratory symptoms – typical of viral conjunctivitis.

When to See a Doctor

Most cases of conjunctivitis improve with simple home care, but certain situations require prompt medical evaluation.

• Symptoms worsen after 24–48 hours despite home measures.
• Intense pain, severe photophobia, or a sudden decrease in vision.
• Thick purulent discharge that does not clear with wiping.
• History of recent eye surgery, trauma, or contact lens wear.
• Neonates with any eye redness, discharge, or swelling.
• Accompanying systemic signs such as high fever, stiff neck, or rash.
• Exposure to chemicals, industrial acids, or alkali solutions.
• Recurrent episodes that do not respond to over‑the‑counter treatment.

These red flags may indicate a more serious infection (e.g., bacterial keratitis), an allergic reaction requiring prescription medication, or an underlying systemic disease.

Diagnosis

Diagnosis of conjunctivitis is primarily clinical, but a thorough assessment helps distinguish the type and rule out complications.

History taking

• Onset, duration, and progression of symptoms.
• Recent contact with sick individuals, swimming pools, or pets.
• Allergy history, medication use, and contact‑lens habits.
• Systemic illnesses or recent infections.

Physical examination

• Visual acuity test to confirm no vision loss.
• Slit‑lamp examination to evaluate conjunctival injection, discharge, corneal clarity, and presence of follicles or papillae.
• Fluorescein staining – highlights any corneal abrasion or ulcer.
• Palpation of preauricular lymph nodes (enlarged nodes suggest viral etiology).

Laboratory / ancillary tests (when needed)

• Conjunctival swab for bacterial culture and sensitivity (especially for purulent discharge).
• PCR testing for viral DNA/RNA if atypical or severe viral infection is suspected.
• Allergy skin testing or serum specific IgE if allergic conjunctivitis is recurrent.
• Neonatal eye swabs for C. trachomatis or N. gonorrhoeae (Gram stain, nucleic‑acid amplification).

Treatment Options

Management depends on the underlying cause. The goal is to relieve symptoms, eliminate the pathogen (if infectious), and prevent complications.

Viral Conjunctivitis

• Usually self‑limited; resolves in 1–2 weeks.
• Cool compresses and artificial tears for comfort.
• Strict hygiene – hand washing, avoiding eye rubbing, and not sharing towels.
• Antiviral therapy (e.g., topical ganciclovir) only for herpes simplex keratoconjunctivitis.

Bacterial Conjunctivitis

• Topical antibiotics (e.g., erythromycin ointment, fluoroquinolone drops) for 5‑7 days.
• Oral antibiotics are reserved for severe cases (e.g., Neisseria gonorrhoeae).
• Warm compresses to loosen crusted discharge.

Allergic Conjunctivitis

• Cool compresses and preservative‑free artificial tears.
• Topical antihistamines or mast‑cell stabilizers (e.g., olopatadine, ketotifen).
• Short‑course topical corticosteroids for severe or refractory cases (under ophthalmologist supervision).
• Avoidance of the offending allergen when possible.

Irritant / Chemical Conjunctivitis

• Immediate copious irrigation with sterile saline or clean water for at least 15 minutes.
• Follow‑up examination to ensure no corneal damage.
• Topical antibiotics if secondary bacterial infection is suspected.

Supportive/Home Care for All Types

• Artificial tears (preservative‑free) every 2‑4 hours.
• Hygienic measures – wash hands before and after touching the eyes, use separate pillowcases.
• Do not wear contact lenses until the eye is completely symptom‑free.
• Discard or replace eye makeup that may have become contaminated.

Prevention Tips

Most cases of conjunctivitis can be avoided with simple daily habits.

• Wash hands frequently with soap and water for at least 20 seconds.
• Use hand sanitizer if soap isn’t available, but wash hands before touching eyes.
• Avoid touching or rubbing the eyes.
• Disinfect shared surfaces (doorknobs, faucets, phone screens) regularly.
• Never share towels, washcloths, or eye cosmetics.
• Follow proper contact‑lens hygiene – clean case daily, replace lenses as directed, and avoid sleeping in lenses unless approved.
• Wear protective eyewear when swimming in chlorinated pools or handling chemicals.
• Use air filters and keep windows closed during high pollen seasons if you have allergic conjunctivitis.
• For newborns, apply prophylactic ophthalmic ointment (e.g., erythromycin) as recommended by pediatrics guidelines to prevent neonatal infection.

Emergency Warning Signs

Key Take‑aways

• Conjunctivitis is inflammation of the thin membrane covering the eye; it is usually benign but highly contagious when viral or bacterial.
• Common causes include viruses (adenovirus), bacteria (Staph, Strep), allergens, chemicals, and poor contact‑lens hygiene.
• Typical signs are redness, discharge, itching, and a gritty feeling.
• Seek professional care if pain, vision change, thick discharge, or systemic symptoms develop.
• Diagnosis is chiefly clinical; cultures or PCR are reserved for atypical or severe cases.
• Treatment ranges from supportive care for viral forms to topical antibiotics for bacterial types and antihistamines or steroids for allergic forms.
• Prevention hinges on hand hygiene, avoiding eye contact, proper lens care, and minimizing exposure to irritants and allergens.
• Red‑flag emergency signs require immediate ophthalmologic evaluation to prevent permanent damage.

For the most current recommendations and personalized advice, always consult a qualified eye‑care professional. Information in this article is based on guidelines from the Mayo Clinic, CDC, NIH, WHO, and the Cleveland Clinic.

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