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Conjunctivitis (Pink Eye)

What is Conjunctivitis (pink eye)?

Conjunctivitis, commonly called “pink eye,” is an inflammation of the conjunctiva – the thin, transparent tissue that lines the inside of the eyelids and covers the white part of the eye (the sclera). When the conjunctiva becomes irritated or infected, tiny blood vessels in the tissue dilate, giving the eye a pink or reddish appearance. The condition can affect one eye or both and is usually not serious, but it can be uncomfortable and, in some cases, contagious.

Common Causes

Conjunctivitis is a symptom, not a disease itself. It can be triggered by a variety of agents. The most frequent causes are:

• Viral infections – adenoviruses are the leading culprits; other viruses such as herpes simplex, varicella‑zoster, or enteroviruses can also cause it.
• Bacterial infections – common bacteria include Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis.
• Allergic reactions – pollen, animal dander, dust mites, or cosmetics can trigger an allergic conjunctivitis.
• Irritants – smoke, chlorine in swimming pools, chemical fumes, or accidental exposure to household cleaners.
• Contact‑lens wear – improper cleaning, overwearing, or a poor fit can introduce bacteria or irritants.
• Dry eye syndrome – chronic dryness can inflame the conjunctiva, especially in older adults.
• Foreign bodies – tiny particles (e.g., sand or eyelashes) that scratch the conjunctiva.
• Eye trauma – scratches or blunt injury can lead to secondary inflammation.
• Systemic diseases – autoimmune conditions such as rheumatoid arthritis or inflammatory bowel disease may cause a type known as “autoimmune conjunctivitis.”
• Neonatal causes – Chlamydia trachomatis or gonorrhea infections acquired during birth.

Associated Symptoms

While the hallmark sign is redness, many other symptoms often accompany conjunctivitis. The exact pattern can help differentiate the cause.

• Discharge – watery or mucoid in viral cases; thick, yellow‑green in bacterial cases.
• Itching or burning – especially prominent in allergic conjunctivitis.
• Gritty sensation – as if something is in the eye.
• Crusting of eyelashes – common after sleep with bacterial discharge.
• Swelling of the eyelids – mild to moderate edema.
• Photophobia – increased sensitivity to light, more typical of viral or severe bacterial forms.
• Reduced vision – usually mild but can occur if the cornea becomes involved.
• Fever, sore throat, or upper‑respiratory symptoms – often accompany viral conjunctivitis.

When to See a Doctor

Most cases of pink eye improve with basic care, but certain situations warrant prompt professional evaluation:

• Symptoms last longer than 7‑10 days without improvement.
• Severe pain, intense redness, or swelling that spreads beyond the eye.
• Vision changes, such as blurred vision or double vision.
• Light sensitivity that interferes with daily activities.
• Excessive discharge that is thick, purulent, or constantly dripping.
• Recent eye injury, surgery, or use of contact lenses.
• In infants, newborns, or immunocompromised individuals – infections can progress quickly.
• If you suspect a sexually transmitted infection (e.g., gonorrhea, chlamydia) is the cause.

Diagnosis

Diagnosis of conjunctivitis is primarily clinical, based on a careful history and eye examination. The typical steps include:

1. Medical history – onset, duration, exposures (contacts, travel, allergies), contact‑lens use, systemic symptoms.
2. Visual acuity test – to rule out significant vision loss.
3. External eye exam – using a slit‑lamp or a simple penlight to assess redness, discharge, and eyelid swelling.
4. Fluorescein staining – a dye that highlights corneal abrasions or ulcers that may accompany severe infection.
5. Swab of discharge – sent for bacterial culture or viral PCR when the presentation is atypical, severe, or does not respond to first‑line therapy.
6. Allergy testing – skin prick or serum IgE testing may be ordered if allergic conjunctivitis is suspected.

Treatment Options

Therapy depends on the underlying cause. Below are the main approaches.

Viral Conjunctivitis

• Supportive care – artificial tears, cold compresses, and good eyelid hygiene.
• Antiviral medication – reserved for herpes simplex or varicella‑zoster eye disease (e.g., oral acyclovir or topical trifluridine).
• Isolation measures – avoid close contact for 24‑48 hours after symptoms appear to limit spread.

Bacterial Conjunctivitis

• Topical antibiotics – erythromycin ointment, trimethoprim‑polymyxin B drops, or fluoroquinolone drops for contact‑lens wearers.
• Typically used for 5‑7 days; symptoms often improve within 24‑48 hours.
• Systemic antibiotics are rarely needed unless there is associated sinusitis, orbital cellulitis, or in neonatal cases.

Allergic Conjunctivitis

• Topical antihistamines/mast cell stabilizers – olopatadine, ketotifen, or azelastine drops.
• Oral antihistamines – cetirizine or loratadine for broader allergic control.
• Cold compresses and avoidance of the allergen.

Irritant‑induced Conjunctivitis

• Rinse the eye with sterile saline or clean water immediately after exposure.
• Use lubricating drops to soothe the surface.
• Remove the offending agent (e.g., stop using a new cosmetic).

Adjunctive Home Care (All Types)

• Wash hands frequently and avoid touching the eyes.
• Use a clean, warm compress (5‑10 minutes, 3‑4 times daily) to reduce crusting.
• Discard any eye cosmetics or contact‑lens solutions used in the past 24 hours.
• Do not share towels, pillowcases, or eye drops.

Prevention Tips

Because many forms of conjunctivitis are contagious, simple hygiene habits can dramatically lower risk.

• Wash hands with soap and water for at least 20 seconds, especially before handling contacts or touching your face.
• Use alcohol‑based hand sanitizer when soap isn’t available.
• Avoid rubbing your eyes.
• If you wear contact lenses, follow the replacement schedule and disinfect lenses daily.
• Replace eye makeup every 3‑6 months and discard any product that becomes contaminated.
• Do not share eye drops, towels, or pillowcases.
• For allergy sufferers, keep windows closed during high pollen counts and use HEPA air filters.
• Children with pink eye should stay home from school or daycare until they’re no longer infectious (usually 24 hours after start of effective therapy).

Emergency Warning Signs

Key Takeaways

Conjunctivitis is an eye condition that ranges from a mild nuisance to a more serious infection. Understanding the cause—viral, bacterial, allergic, or irritant—guides appropriate treatment. Most cases resolve with good hygiene and, when needed, topical therapy. However, persistent symptoms, vision changes, or intense pain should prompt a prompt visit to a healthcare professional. By practicing preventive measures and recognizing warning signs, you can protect your eyes and minimize the spread to others.

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References:

• Mayo Clinic. Conjunctivitis (pink eye). https://www.mayoclinic.org/diseases-conditions/pink-eye/symptoms-causes/syc-20377095
• Centers for Disease Control and Prevention. Conjunctivitis. https://www.cdc.gov/conjunctivitis/index.html
• American Academy of Ophthalmology. Pink Eye (Conjunctivitis) Overview. https://www.aao.org/eye-health/diseases/what-is-conjunctivitis
• National Eye Institute. Conjunctivitis. https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/conjunctivitis
• Cleveland Clinic. Pink Eye (Conjunctivitis) Causes and Treatments. https://my.clevelandclinic.org/health/diseases/13620-pink-eye-conjunctivitis

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