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Epidemic Keratoconjunctivitis (EKC) – A Complete Patient‑Friendly Guide

Overview

Epidemic keratoconjunctivitis (EKC) is a highly contagious viral infection of the eye that involves both the conjunctiva (the thin membrane covering the white of the eye and the inner eyelid) and the cornea (the clear front surface of the eye). It is caused primarily by certain strains of adenovirus, most commonly types 8, 19, and 37, although other adenoviral serotypes can also be responsible.

EKC is called “epidemic” because it tends to occur in outbreaks, especially in settings where people are in close contact—such as schools, day‑care centers, military barracks, and health‑care facilities. The disease can affect anyone, but the highest incidence is seen in children aged 5‑14 years and in adults who work in high‑density environments.

Worldwide, adenoviral eye infections account for roughly 2–5% of all conjunctivitis cases. In the United States, EKC accounts for an estimated 15,000–30,000 office visits each year, with occasional larger outbreaks reported in Asia and Europe.<sup>1</sup>

Symptoms

Symptoms usually appear 5–12 days after exposure and can last from 2 weeks up to several months, depending on severity.

• Redness (hyperemia) – diffuse or sectoral redness of the sclera and conjunctiva.
• Watery or mucopurulent discharge – a thick, often “sticky” discharge that may crust over the eyelashes, especially upon waking.
• Intense foreign‑body sensation – patients describe a feeling of grit, sand, or a “bump” on the eye.
• Photophobia – heightened sensitivity to light, making bright environments uncomfortable.
• Blepharospasm – involuntary tightening of the eyelids, often a protective response to pain.
• Follicular conjunctivitis – small, white, raised bumps (follicles) on the underside of the eyelid margin.
• Subepithelial infiltrates (SEIs) – fine, cloudy deposits that develop in the cornea a week or more after the acute phase, causing blurred vision and glare.
• Reduced visual acuity – especially when SEIs involve the visual axis.
• Lacrimation (tearing) – excessive tearing due to irritation.
• Swollen eyelids (edema) – may be mild to moderate.

Not all patients will have every symptom; some may experience a mild “pink eye” that resolves quickly, while others develop a more severe keratitis with visual impairment.

Causes and Risk Factors

Viral Etiology

The primary agents are adenoviruses—non‑enveloped, double‑stranded DNA viruses that are remarkably stable in the environment. Types 8, 19, and 37 are the most common culprits for EKC, but other serotypes (e.g., 3, 4, 7) have been implicated in sporadic cases.

Modes of Transmission

• Direct contact – touching an infected eye and then touching another person’s eye or a surface.
• Fomites – contaminated towels, cosmetics, ophthalmic instruments, or shared computer keyboards.
• Aerosol droplets – coughing, sneezing, or talking in close proximity can spread viral particles.

Risk Factors

• Living or working in crowded environments (schools, day‑care centers, military, prisons).
• Frequent eye‑touching or poor hand hygiene.
• Use of shared eye‑care products (e.g., eye drops, makeup applicators).
• Recent ocular surgery or contact‑lens wear—disruption of the ocular surface can facilitate infection.
• Immunocompromised state (HIV, chemotherapy, organ transplantation) – may increase severity and duration.

Diagnosis

Clinical Evaluation

Diagnosis is primarily clinical, based on a thorough history and eye examination. Key findings that point toward EKC include:

• Sudden onset of unilateral or bilateral red eye with watery/mucous discharge.
• Presence of large conjunctival follicles and a “cobblestone” appearance on the palpebral conjunctiva.
• Development of subepithelial infiltrates after the acute phase.

Laboratory Tests (when needed)

1. Polymerase chain reaction (PCR) – detects adenoviral DNA from conjunctival swabs; highly sensitive and specific.
2. Rapid antigen detection kits – provide results within 15–30 minutes, useful during outbreaks.
3. Viral culture – less common due to longer turnaround time.

Testing is usually reserved for severe outbreaks, atypical presentations, or when ruling out bacterial superinfection.

Treatment Options

There is no cure that directly eliminates adenovirus from the eye; treatment focuses on symptom relief, preventing complications, and limiting spread.

Medications

• Topical lubricants (artificial tears) – soothe irritation and dilute discharge.
• Cold compresses – reduce swelling and discomfort.
• Topical corticosteroids (e.g., prednisolone acetate 1%) – used selectively for severe keratitis or persistent subepithelial infiltrates. Must be prescribed and monitored because prolonged use can raise intraocular pressure and increase infection risk.
• Topical antihistamine/mast‑cell stabilizer drops – help with itching and redness.
• Oral antivirals – not effective against adenovirus; therefore, they are not recommended.

Procedural Interventions

• Debridement of subepithelial infiltrates – performed by an ophthalmologist in refractory cases to improve visual acuity.
• Therapeutic contact lenses – bandage lenses may promote epithelial healing after severe keratitis, but they must be managed under strict aseptic conditions.

Lifestyle & Supportive Measures

• Strict hand‑washing with soap and water for at least 20 seconds before and after touching the eyes.
• Avoid rubbing the eyes; use a clean tissue if tearing occurs.
• Discontinue use of eye makeup or contact lenses until the infection resolves.
• Isolate the patient (e.g., stay home from school/work) until discharge is no longer present—typically 7–10 days after symptom onset.

Living with Epidemic Keratoconjunctivitis (EKC)

Daily Management Tips

• Follow a regimented drop schedule as prescribed; missing doses can prolong inflammation.
• Use preservative‑free artificial tears every 2–4 hours to keep the ocular surface moist.
• Protect your eyes with sunglasses outdoors to reduce photophobia.
• Maintain a clean environment—wash pillowcases, towels, and washcloths daily in hot water (≥60 °C) and change them frequently.
• Monitor visual changes—any new blurring, halos, or decreased acuity warrants prompt evaluation.
• Stay hydrated and rest—systemic hydration supports mucosal healing.
• Document symptoms—keeping a simple diary helps your eye‑care provider assess response to therapy.

Prevention

• Hand hygiene – the single most effective measure. Use alcohol‑based hand rubs if soap and water are unavailable.
• Avoid sharing personal items – towels, eye cosmetics, contact‑lens cases, and eyeglasses.
• Disinfect surfaces – wipe countertops, doorknobs, and shared equipment with EPA‑registered disinfectants effective against adenovirus (e.g., bleach solution 1:10).
• Proper contact‑lens care – use fresh solution daily, replace lenses as recommended, and avoid wearing lenses while symptomatic.
• Eye‑care provider precautions – clinicians should use gloves, slit‑lamp barriers, and sterilize instruments between patients.
• Stay home when ill – individuals with EKC should avoid school, work, or public places until discharge has cleared.

Complications

Although EKC is usually self‑limited, several complications can arise, particularly if treatment is delayed or inappropriate.

• Persistent subepithelial infiltrates – may cause chronic glare, reduced contrast sensitivity, and, in rare cases, permanent scarring.
• Corneal ulceration – secondary bacterial infection can lead to a painful ulcer that threatens vision.
• Secondary bacterial conjunctivitis – may require topical antibiotics.
• Increased intraocular pressure (IOP) – associated with prolonged topical steroid use.
• Conjunctival scarring – can affect tear film distribution, leading to dry‑eye symptoms.
• Spread to the other eye – up to 40% of unilateral cases progress to bilateral involvement.

When to Seek Emergency Care

References

1. Mayo Clinic. “Viral conjunctivitis.” Accessed April 2026.
2. Centers for Disease Control and Prevention. “Adenovirus Eye Infections.” Updated 2023.
3. World Health Organization. “Adenovirus infection.” 2022.
4. Cleveland Clinic. “Keratoconjunctivitis – Signs, Symptoms, Treatment.” 2024.
5. Lin C, et al. “Epidemic keratoconjunctivitis: Current management and future perspectives.” *Ophthalmology* 2021;128(3):341‑350. doi:10.1016/j.ophtha.2020.11.012.
6. U.S. National Library of Medicine, NIH. “Adenoviral conjunctivitis.” 2023.

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