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Keratitis (Eye Redness)

What is Keratitis (eye redness)?

Keratitis is inflammation of the cornea – the clear, dome‑shaped surface that covers the front of the eye and helps focus light. When the cornea becomes irritated or infected, the eye often looks red, feels gritty, and may be painful. Although “keratitis” describes the inflammation itself, most people notice it first because the eye looks blood‑shot, which is why the condition is frequently associated with “eye redness.”

The cornea is essential for clear vision; even a small ulcer or swelling can degrade visual acuity temporarily or permanently if not treated promptly. Keratitis can be caused by bacteria, viruses, fungi, parasites, trauma, or underlying eye diseases such as dry‑eye syndrome. The severity ranges from mild irritation that resolves in a few days to sight‑threatening ulcers that require urgent care.

Common Causes

Below are the most frequent triggers for keratitis, grouped by type of agent:

• Contact‑lens wear – especially when lenses are worn overnight, are poorly cleaned, or are stored in contaminated solution.
• Bacterial infection – common culprits include Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus pneumoniae.
• Viral infection – most often the herpes simplex virus (HSV) and, less commonly, varicella‑zoster virus.
• Fungal infection – usually follows trauma with vegetative material (e.g., a tree branch) and involves organisms such as Fusarium and Aspergillus.
• Parasitic infection – Acanthamoeba keratitis is linked to contaminated water exposure, often in contact‑lens users.
• Ultraviolet (UV) exposure – “Photokeratitis” occurs after intense UV light exposure (e.g., snow blindness or welding). It is essentially a sunburn of the cornea.
• Mechanical trauma – scratches or foreign bodies (dust, metal fragments) that breach the corneal epithelium.
• Dry‑eye syndrome & ocular surface disease – chronic dryness can cause micro‑abrasions that predispose the cornea to inflammation.
• Chemical burns – exposure to acids, alkalis, or industrial chemicals can rapidly inflame the cornea.
• Autoimmune or inflammatory conditions – diseases such as rheumatoid arthritis, Stevens‑Johnson syndrome, or ocular rosacea may produce sterile keratitis.

Associated Symptoms

While redness is the most visible sign, keratitis often presents with several other symptoms. The pattern of accompanying features can give clues about the underlying cause:

• Eye pain or discomfort – ranging from mild irritation to severe throbbing.
• Foreign‑body sensation – a feeling that something is stuck in the eye.
• Excessive tearing or watery discharge – the eye may produce tears in an attempt to flush the irritant.
• Purulent (pus‑filled) or mucous discharge – more typical of bacterial infection.
• Photophobia – heightened sensitivity to light.
• Reduced vision or blurred sight – especially if the central cornea is involved.
• Eye swelling (edema) – eyelids may appear puffy.
• White or gray spot on the cornea (ulcer) – visible on slit‑lamp examination; may appear as a “dot” to the patient.

When to See a Doctor

Keratitis can progress quickly, so early evaluation is crucial. Seek professional care promptly if you experience any of the following:

• Redness that does not improve within 24‑48 hours.
• Moderate to severe pain, especially if it wakes you at night.
• Blurred vision or any sudden change in visual acuity.
• Presence of a white spot, ulcer, or “hazy” area on the cornea.
• Excessive discharge that is yellow, green, or thick.
• History of recent contact‑lens wear, eye injury, or exposure to chemicals.
• Sensitivity to light that interferes with everyday activities.
• Symptoms persisting despite over‑the‑counter lubricating drops.

Diagnosis

Eye specialists (ophthalmologists or optometrists) use a combination of history‑taking, visual tests, and specialized equipment to confirm keratitis and determine its cause.

Clinical Evaluation

• History – questions about lens wear, recent injuries, exposure to water/soil, systemic illnesses, and medication use.
• Visual acuity test – determines any loss of vision.
• Flashlight examination – assesses basic redness, discharge, and pupil response.

Slit‑Lamp Biomicroscopy

This is the gold‑standard exam for corneal disease. A high‑intensity light and magnifying lens allow the clinician to see:

• Corneal epithelial defects (scratches, ulcer).
• Depth and size of any ulcer.
• Presence of infiltrates (white inflammatory cells) indicating infection.
• Staining patterns after fluorescein dye is applied (bright green spots highlight epithelial loss).

Microbiological Testing (when infection is suspected)

• Corneal scraping – a tiny sample of tissue is taken for Gram stain, culture, and polymerase chain reaction (PCR) to identify bacteria, fungi, viruses, or Acanthamoeba.
• Contact‑lens solution analysis – may be sent if a lens‑related outbreak is suspected.

Additional Imaging (rarely needed)

• Anterior segment optical coherence tomography (AS‑OCT) – provides cross‑sectional images of corneal thickness.
• Confocal microscopy – helps visualize organisms such as Acanthamoeba in situ.

Treatment Options

Therapy is tailored to the cause, severity, and presence of risk factors (e.g., contact‑lens wear). Early treatment improves outcomes and reduces the risk of scarring.

General Measures

• Stop wearing contact lenses – discard the current pair and give the eye a rest.
• Lubricating eye drops – preservative‑free artificial tears can soothe mild irritation (use only if infection is ruled out).
• Cold compresses – may relieve discomfort from photokeratitis or mild inflammation.

Medical Treatments

• Antibiotic eye drops or ointments – broad‑spectrum fluoroquinolones (e.g., moxifloxacin) are first‑line for bacterial keratitis. Culture‑guided therapy is used for resistant strains.
• Antiviral therapy – topical trifluridine or ganciclovir for HSV keratitis; oral acyclovir/valacyclovir for extensive disease.
• Antifungal agents – natamycin 5% drops are preferred for filamentous fungi; voriconazole may be used for deeper infections.
• Acanthamoeba treatment – combination of polyhexamethylene biguanide (PHMB) and chlorhexidine, often for several months.
• Corticosteroid drops – can reduce scarring in non‑infectious or healed infectious keratitis, but only after the infection is controlled and under specialist supervision.
• Pain control – oral analgesics (acetaminophen, ibuprofen) or, in severe cases, prescription oral opioids for short‑term use.
• Systemic therapy – oral antibiotics (e.g., doxycycline) for certain bacterial types or to address associated rosacea.

Surgical Interventions (rare, for advanced disease)

• Therapeutic corneal transplant (penetrating keratoplasty) – replaces severely damaged corneal tissue.
• Amniotic membrane graft – promotes healing in persistent ulcers.
• Anterior chamber washout – used for infectious endophthalmitis that extends beyond the cornea.

Prevention Tips

Many cases of keratitis are avoidable with simple hygienic habits and protective measures:

• Proper contact‑lens care – wash hands before handling lenses, use fresh disinfecting solution every night, never top‑up old solution, and replace lenses as recommended.
• Limit overnight wear – unless lenses are specifically designed for extended wear, remove them before sleep.
• Avoid water exposure – do not swim, shower, or use hot tubs with lenses in place; use waterproof goggles if exposure is unavoidable.
• Eye protection – wear safety glasses or goggles when working with chemicals, gardening, or participating in high‑velocity sports.
• Maintain ocular surface health – treat dry‑eye disease with lubricating drops, warm compresses, or prescription omega‑3 supplements.
• Practice good hygiene – avoid sharing eye makeup, replace mascara every three months, and discard old eye drops.
• Promptly treat ocular injuries – rinse the eye with clean water or saline and seek care if a foreign body is embedded.
• Vaccination – shingles vaccine can reduce the risk of varicella‑zoster keratitis in older adults.

Emergency Warning Signs

Key Take‑aways

Keratitis is an inflammation of the cornea that commonly manifests as eye redness. While many mild cases resolve with proper hygiene and lubricating drops, infections—especially those linked to contact lenses or trauma—can progress to sight‑threatening ulcers. Early recognition, prompt medical evaluation, and adherence to treatment plans are essential for preserving vision.

Always consult a qualified eye care professional if you notice persistent redness, pain, discharge, or any change in vision. Early intervention saves sight.

References:

• Mayo Clinic. “Keratitis.” mayoclinic.org. Accessed April 2026.
• American Academy of Ophthalmology. “Contact Lens‑Related Corneal Infections.” aao.org. 2023.
• Centers for Disease Control and Prevention. “Acanthamoeba Keratitis.” cdc.gov. Updated 2022.
• National Institute of Allergy and Infectious Diseases (NIH). “Herpes Simplex Keratitis.” niaid.nih.gov. 2024.
• Cleveland Clinic. “Photokeratitis (UV Keratitis).” clevelandclinic.org. 2023.

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