Acute Conjunctivitis (Pink Eye)

What is Acute Conjunctivitis?

Acute conjunctivitis, commonly called “pink eye,” is a rapid‑onset 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). The condition may affect one eye or both eyes and is usually characterized by redness, tearing, itching, and a discharge that can make the eyelids stick together, especially after sleep.

The term “acute” simply means that the inflammation appears suddenly and lasts from a few days up to two weeks. It is one of the most frequent eye complaints seen in primary‑care clinics and emergency departments.

Although most cases are mild and self‑limiting, some forms can threaten vision if not treated promptly, making it essential to recognize the underlying cause and seek care when warning signs appear.

Common Causes

Acute conjunctivitis can be classified by the type of pathogen or irritant that triggers the inflammation. The most common causes include:

• Viral infection – Adenoviruses are responsible for >50 % of cases; other viruses (herpes simplex, varicella‑zoster, enteroviruses) can also be involved.
• Bacterial infection – Frequently caused by Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae, or Moraxella catarrhalis. In newborns, Neisseria gonorrhoeae and Chlamydia trachomatis are important.
• Allergic reaction – Seasonal pollen, pet dander, dust mites, or cosmetics can provoke an IgE‑mediated response.
• Irritant exposure – Smoke, chlorine, fumes, or foreign bodies can mechanically inflame the conjunctiva.
• Contact‑lens wear – Improper hygiene or overwearing lenses can lead to bacterial or Acanthamoeba‑related conjunctivitis.
• Eye‑drop contamination – Sharing drops or using expired solutions introduces bacteria.
• Systemic disease – Autoimmune conditions such as rheumatoid arthritis or Stevens‑Johnson syndrome may involve the conjunctiva.
• Neonatal ophthalmia – Acquired during delivery from maternal genital tract infections.
• Fungal infection – Rare, but molds (e.g., Fusarium) can cause keratoconjunctivitis, especially after trauma.
• Trauma – Corneal scratches or chemical burns can trigger an acute inflammatory response that mimics infectious conjunctivitis.

Associated Symptoms

Symptoms often overlap, but certain patterns help clinicians narrow the cause:

• Redness that starts at the inner corner and spreads outward.
• Watery or mucoid discharge (clear in viral cases, thick yellow/green in bacterial).
• Itching or burning sensation (prominent in allergic conjunctivitis).
• Gritty feeling, as if “something is in the eye.”
• Photophobia (light sensitivity) – more common when the cornea is involved.
• Swollen eyelids or eyelid edema.
• Fever, sore throat, or upper‑respiratory symptoms – suggest viral etiology.
• Swollen lymph nodes in front of the ear (pre‑auricular adenopathy) – typical for viral infections.
• Blurred vision – should be investigated promptly.

When to See a Doctor

Most cases of acute conjunctivitis improve with basic care, yet you should schedule a medical evaluation if any of the following occur:

• Symptoms persist longer than 7–10 days without improvement.
• Severe pain, intense redness, or a sensation of a foreign body that does not resolve.
• Vision becomes blurry or you notice halos around lights.
• Eye discharge is thick, pus‑filled, or has a foul odor.
• There is swelling of the eyelids that does not improve with warm compresses.
• Rapid onset of symptoms in a newborn (first month of life).
• History of contact‑lens wear combined with redness and pain.
• Signs of an allergic reaction affecting both eyes with accompanying asthma or eczema flare‑ups.

Diagnosis

Diagnosis relies on a careful history, visual inspection, and occasionally laboratory testing.

Clinical examination

• Visual acuity test – ensures vision is not compromised.
• Slit‑lamp biomicroscopy – magnifies the conjunctiva, cornea, and anterior chamber.
• Fluorescein staining – highlights corneal abrasions or ulcerations.
• Eyelid eversion – allows examination of the upper lid for discharge or foreign bodies.

When lab tests are helpful

• Gram stain and culture of conjunctival swab – identifies bacterial pathogens, especially in severe or atypical cases.
• Polymerase chain reaction (PCR) – detects viral DNA/RNA (e.g., adenovirus, HSV).
• Rapid antigen tests – point‑of‑care kits for adenovirus are available in some clinics.
• Serology – for chlamydial or gonococcal infections in neonates.

Treatment Options

Treatment is tailored to the underlying cause. Below are general strategies plus specific therapies.

General (self‑care) measures

• Apply a clean, warm compress to the closed eyelids 5–10 minutes, 3–4 times daily to reduce crusting and promote drainage.
• Practice strict hand‑washing before touching the eyes or applying medications.
• Avoid rubbing the eyes; use a clean tissue to gently wipe away discharge.
• Discard any eye makeup or contact‑lens solution used during the episode.
• Use artificial tears (preservative‑free) to relieve irritation.

Pharmacologic treatment

• Viral conjunctivitis – Usually self‑limiting; supportive care (lubricants, cold compresses). Antiviral drops (e.g., trifluridine) are reserved for HSV or varicella‑zoster involvement.
• Bacterial conjunctivitis – First‑line topical antibiotics such as:
  • Erythromycin ophthalmic ointment
  • Polymyxin‑B/trimethoprim drops
  • Fluoroquinolone drops (e.g., moxifloxacin) for contact‑lens wearers or suspected resistant organisms.
  A 5‑day course is typically sufficient; improvement should be seen within 48 hours.
• Allergic conjunctivitis – Antihistamine/mast‑cell stabilizer drops (e.g., olopatadine, ketotifen). For severe cases, short courses of topical corticosteroids may be prescribed under close supervision.
• Neonatal ophthalmia – Immediate systemic antibiotics (e.g., intravenous ceftriaxone) and topical erythromycin; prophylaxis with erythromycin ointment is standard in many countries.

When oral medications are needed

• Systemic antibiotics for gonococcal conjunctivitis or severe bacterial cases.
• Oral antihistamines (cetirizine, loratadine) to control the allergic component.

Prevention Tips

Many cases of acute conjunctivitis are preventable with simple hygiene practices:

• Wash hands with soap and water for at least 20 seconds before and after touching your eyes.
• Avoid sharing towels, pillowcases, or cosmetics.
• Disinfect contact‑lens cases daily and replace lenses as directed.
• If you wear eye makeup, replace mascara every 3 months and discard any product that becomes clumpy.
• Stay home from school or work while symptomatic, especially with viral conjunctivitis, to reduce spread.
• Use protective eyewear when swimming in chlorinated pools or when exposed to dust, chemicals, or wind.
• For children with seasonal allergies, keep windows closed during high pollen counts and consider antihistamine eye drops prophylactically.
• Newborns should receive prophylactic erythromycin ointment immediately after birth, per CDC guidelines.

Emergency Warning Signs

Key Take‑aways

Acute conjunctivitis is a common, usually mild eye condition that can be viral, bacterial, allergic, or irritant‑related. Recognizing the pattern of symptoms, practicing good ocular hygiene, and knowing when to seek professional care are essential for a quick recovery and for preventing spread to others. If you notice any red‑flag warning signs, do not delay—contact an eye‑care professional or visit the nearest emergency department.

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References:

• Mayo Clinic. “Conjunctivitis (pink eye).” https://www.mayoclinic.org
• Centers for Disease Control and Prevention. “Bacterial Conjunctivitis.” https://www.cdc.gov
• National Eye Institute. “Conjunctivitis (Pink Eye).” https://www.nei.nih.gov
• Cleveland Clinic. “Allergic Conjunctivitis.” https://my.clevelandclinic.org
• World Health Organization. “Prevention of Neonatal Ophthalmia.” https://www.who.int