Corneal Inflammation (Keratitis) - Causes, Treatment & When to See a Doctor

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What is Corneal Inflammation (Keratitis)?

Keratitis, commonly called corneal inflammation, is a condition in which the clear front surface of the eye – the cornea – becomes swollen, red, and painful. The cornea is essential for focusing light onto the retina, so any disruption can impair vision and, if left untreated, may lead to scarring or permanent loss of visual acuity. Keratitis can be mild and self‑limited or severe enough to require urgent medical care.

Most cases are caused by an infection (bacterial, viral, fungal, or parasitic) or by non‑infectious irritants (dry eye, contact‑lens wear, trauma). The underlying mechanism is inflammation of the corneal epithelium, stroma, or endothelium, which leads to edema, ulceration, and sometimes infiltration of immune cells.

Common Causes

• Bacterial infection – often related to contact‑lens misuse or ocular trauma.
• Viral infection – most frequently herpes simplex virus (HSV) or varicella‑zoster virus.
• Fungal infection – common after plant or soil trauma, especially in warm, humid climates.
• Parasitic infection – Acanthamoeba keratitis is linked to poor contact‑lens hygiene.
• Contact‑lens wear – especially extended‑wear lenses, overnight wear, or lenses contaminated with bacteria.
• Dry eye syndrome – chronic ocular surface dryness can predispose the cornea to inflammation.
• Physical trauma – scratches, foreign bodies, or chemical burns.
• Ultraviolet (UV) exposure – photokeratitis (“snow blindness”) from intense UV light.
• Allergic reactions – seasonal or occupational allergens can trigger inflammatory changes.
• Autoimmune disorders – conditions such as rheumatoid arthritis or Stevens‑Johnson syndrome may involve the cornea.

Associated Symptoms

People with keratitis often notice a combination of the following:

• Eye redness, especially around the cornea
• Severe burning, stinging, or gritty sensation (“feels like sand in the eye”)
• Excessive tearing or watery discharge
• Photophobia – increased sensitivity to light
• Blurry or hazy vision, sometimes with a “halo” effect
• Swelling of the eyelids (eyelid edema)
• White or yellowish spot on the cornea (ulcer or infiltrate)
• Feeling of pressure or fullness in the eye

When to See a Doctor

While mild irritation may improve with over‑the‑counter lubricating drops, the following situations warrant prompt evaluation by an eye‑care professional (optometrist or ophthalmologist):

• Pain that is persistent, worsening, or interferes with daily activities.
• Visible white spot, ulcer, or any abnormal patch on the cornea.
• Rapid decline in visual clarity or new double vision.
• Significant photophobia or inability to keep the eye open.
• History of recent contact‑lens wear, especially overnight use.
• History of eye trauma, chemical splash, or exposure to UV light.
• Presence of discharge that is thick, yellow/green, or foul‑smelling.

Diagnosis

Diagnosis of keratitis is a step‑wise process that combines patient history, visual assessment, and specialized testing.

1. Clinical History & Visual Exam

• Questions about recent contact‑lens use, injuries, exposure to water or soil, and systemic diseases.
• Visual acuity testing to quantify any loss of sharpness.
• Examination of the external eye (eyelids, conjunctiva) for redness or discharge.

2. Slit‑Lamp Biomicroscopy

The gold‑standard tool for corneal evaluation. A bright, focused beam of light allows the clinician to see layers of the cornea, detect ulcer size, depth, and any infiltrates.

3. Fluorescein Staining

Fluorescein dye is placed on the ocular surface. Under cobalt blue light, gaps in the epithelium (ulcers) appear as bright green areas, helping gauge the extent of the lesion.

4. Microbiologic Cultures

• Corneal scrapings are taken for Gram stain, bacterial/fungal cultures, and polymerase‑chain‑reaction (PCR) for viral DNA when an infectious cause is suspected.
• For suspected Acanthamoeba, a specialized culture and confocal microscopy are performed.

5. Imaging (if needed)

Anterior segment optical coherence tomography (AS‑OCT) or confocal microscopy can assess stromal depth and monitor healing.

Treatment Options

Treatment depends on the underlying cause, severity, and risk of complications.

Medical Therapy

• Antibiotic eye drops – Broad‑spectrum fluoroquinolones (e.g., moxifloxacin) are first‑line for bacterial keratitis. Culture‑guided therapy is used for resistant organisms.
• Antiviral medication – Topical trifluridine or ganciclovir for HSV keratitis; oral acyclovir or valacyclovir for systemic control.
• Antifungal eye drops – Natamycin 5% suspension is preferred for filamentous fungi; amphotericin B for yeast infections.
• Acanthamoeba therapy – Combination of polyhexamethylene biguanide (PHMB) and chlorhexidine, often with propamidine isethionate.
• Corticosteroid eye drops – Used cautiously after the infection is controlled (usually 48‑72 h) to reduce stromal inflammation and scarring. Not used in active fungal or Acanthamoeba keratitis.
• Pain control – Oral analgesics (acetaminophen or ibuprofen) and, in severe cases, topical cycloplegics (e.g., homatropine) to relieve ciliary spasm.

Adjunctive & Home Care

• Lubricating artificial tears – Preserve surface moisture and promote epithelial healing.
• Cold compresses – Reduce discomfort and edema.
• Strict contact‑lens hygiene – Discontinue lens wear until cleared by a clinician; replace lens case and solution.
• Protective eyewear – Shield eyes from wind, dust, or UV exposure during recovery.

Surgical Interventions (when medical therapy fails)

• Therapeutic penetrating keratoplasty – Full‑thickness corneal transplant for perforation or non‑healing ulcer.
• Lamellar keratoplasty – Partial‑thickness graft for stromal involvement while preserving healthy endothelium.
• Amniotic membrane transplantation – Promotes epithelialization and reduces inflammation.

Prevention Tips

• Hand hygiene – Wash hands thoroughly before handling contact lenses or touching the eyes.
• Follow lens guidelines – Use only approved solutions, replace lenses and cases as recommended, avoid overnight wear unless specifically approved.
• Avoid water exposure – Do not swim, shower, or use hot tubs while wearing contact lenses.
• Protect eyes from trauma – Wear safety goggles during sports, woodworking, or any activity with flying debris.
• Use UV‑blocking sunglasses – Prevent photokeratitis and chronic UV‑induced damage.
• Manage dry eye – Use preservative‑free artificial tears and consider environmental humidifiers.
• Promptly treat ocular infections – Early antiviral or antibacterial therapy reduces the chance of secondary keratitis.
• Regular eye exams – Annual eye checks help spot early corneal changes, especially for contact‑lens wearers.

Emergency Warning Signs

References

• Mayo Clinic. “Keratitis.” https://www.mayoclinic.org
• Cleveland Clinic. “Corneal Ulcer (Keratitis) Treatment.” https://my.clevelandclinic.org
• American Academy of Ophthalmology. “Management of Bacterial Keratitis.” 2023 Clinical Guidelines.
• Centers for Disease Control and Prevention. “Acanthamoeba Keratitis.” https://www.cdc.gov
• World Health Organization. “Prevention of Ocular Infections.” 2022.
• National Institute of Allergy and Infectious Diseases. “Herpes Simplex Virus Keratitis.” 2021.

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