Introduction
Keratitis is inflammation of the cornea—the clear front window of the eye that focuses light and protects deeper structures. When the cornea is inflamed, pain, redness, light sensitivity, and blurred vision are common.
Causes include bacterial, viral, fungal, and parasitic infections, as well as non-infectious irritants, dryness, ultraviolet injury, and autoimmune disease. Contact lens wear with poor hygiene is a major risk for infectious keratitis.
Infectious types range from common bacterial ulcers linked to lenses, to herpes simplex keratitis with recurrent flares, to less common fungal or Acanthamoeba infections after plant trauma or contaminated water exposure.
Prompt eye care matters: untreated keratitis can scar the cornea and permanently reduce vision. Treatment depends on the cause and may include antimicrobial drops, antivirals, supportive care, or—rarely—corneal surgery. This page is general education—urgent eye symptoms need same-day assessment.
Overview
Keratitis is a cornea-focused emergency spectrum: mild sterile irritation can share symptoms with sight-threatening infection, so self-diagnosis is unsafe.
Classification by cause (infectious vs non-infectious vs immune-related) guides therapy. Contact lens history, trauma, cold sores, and immune disease are key clues.
Early diagnosis with slit-lamp exam and directed cultures improves the chance of full recovery; delay raises scarring and vision-loss risk.
- Inflammation of the cornea affecting comfort and vision
- Infectious (bacteria, viruses, fungi, Acanthamoeba) and non-infectious causes
- Contact lens hygiene failures are a leading preventable risk
- Pain, redness, photophobia, blur, tearing, or discharge are typical
- Diagnosis uses exam, fluorescein staining, and cultures when needed
- Untreated disease can scar the cornea or threaten sight
What happens in the body
Infection or injury disrupts the corneal epithelium and may invade deeper stroma. Inflammatory cells and microbial toxins damage clear collagen layers, producing opacity, ulceration, and pain.
Herpes viruses can remain latent and reactivate. Autoimmune inflammation can attack the corneal margin or surface. Dryness and UV exposure weaken defenses and amplify irritation.
- Microbes or irritants breach the corneal surface barrier
- Inflammation clouds the cornea and can form ulcers
- HSV may cause recurrent epithelial or stromal disease
- Nutrient deficits and poor lens hygiene increase susceptibility
Signs and symptoms
Symptoms vary by cause and severity. Common features include:
- Eye pain (sharp or dull) in the affected eye
- Redness and visible inflammation
- Blurred, hazy, or distorted vision
- Sensitivity to light (photophobia)
- Tearing or watery discharge; yellow or green discharge if bacterial
- Foreign-body sensation—feeling that something is in the eye
- Severe unrelieved pain, sudden vision loss, or worsening despite home care (urgent)
Causes and risk factors
More than one pathway can inflame the cornea. Important causes and risks include:
- Bacterial infection (e.g., Pseudomonas, Staphylococcus), often with contact lenses
- Viral infection, especially herpes simplex virus
- Fungal infection after plant material injury or in immunocompromised people
- Acanthamoeba from contaminated water and lens exposure
- Chemical, UV, or dry-environment irritation (non-infectious keratitis)
- Autoimmune diseases such as rheumatoid arthritis or lupus
- Poor hand and lens hygiene; swimming or hot-tub use in lenses
- Older age, diabetes, immune deficiency, and prior eye injury
Diagnosis and evaluation
An eye clinician confirms keratitis and looks for the cause—appearance alone may not tell infection type:
- History of lenses, trauma, cold sores, immune disease, and symptom timeline
- Slit-lamp examination of the cornea and anterior eye
- Fluorescein staining to highlight abrasions or ulcers
- Cultures or scrapings of discharge/corneal tissue for microbes when infection is likely
- Imaging such as OCT in selected complex cases
- Differentiation from conjunctivitis, uveitis, and simple corneal abrasions
Treatment and management
Never start leftover eye drops without advice—wrong treatment can worsen some infections:
- Bacterial keratitis: intensive antibiotic eye drops as prescribed
- Viral (HSV) keratitis: antiviral medicines; supportive care for some viral forms
- Fungal keratitis: antifungal drops or oral agents when indicated
- Acanthamoeba keratitis: specialized anti-amoebic regimens; often prolonged
- Supportive measures: pain control, cycloplegics when prescribed, avoiding lenses during illness
- Warm compresses only if advised; do not self-patch an infected eye
- Severe scarring or non-healing ulcers may need corneal transplant evaluation
- Age-specific dosing and closer monitoring in children and older adults
Prevention, self-care, and lifestyle
Not every condition is fully preventable, but the steps below may lower risk or recurrence:
- Wash hands before handling lenses; never use tap water on lenses or cases
- Avoid swimming or hot tubs while wearing contact lenses
- Replace cases and solutions on schedule; do not sleep in lenses unless specifically approved
- Wear UV-protective sunglasses outdoors
- Eat a balanced diet supporting eye health; keep routine eye exams
- Seek care early for red, painful eyes—especially lens wearers
Possible complications
Delay, missed care, or unsafe self-medication can raise the chance of complications in some cases:
- Corneal scarring with lasting blur or glare
- Significant vision loss or blindness in severe untreated infection
- Recurrent keratitis, especially herpes-related disease
- Short-term escalation of pain and light sensitivity
- Need for surgical intervention when medical therapy fails
When to see a doctor or seek emergency care
Seek prompt medical advice or emergency care if any of the following apply—it is safer not to wait and see:
- Severe eye pain not improving with simple measures
- Sudden or significant vision change
- Persistent redness or swelling of the eye
- Yellow or green discharge
- Symptoms that worsen despite initial care—especially in contact lens wearers
Living with the condition
If you wear contacts, treat any painful red eye as urgent until cleared by an eye professional—remove lenses and take them/your case to the visit if asked.
For herpes-related keratitis, learn your early warning signs and keep follow-up as advised to reduce scarring risk from repeated flares.
Protect the recovering eye from dust, makeup contamination, and unnecessary rubbing while medicines finish their full course.
Frequently asked questions
What are the main symptoms of keratitis?
Eye pain, redness, blurred vision, light sensitivity, tearing or discharge, and a foreign-body sensation. Severe pain or sudden vision change needs urgent care.
How is keratitis diagnosed?
Through history and slit-lamp exam, often with fluorescein staining and cultures when infection is suspected.
What treatments are used?
Cause-specific drops or medicines—antibiotics, antivirals, antifungals, or anti-amoebic agents—and surgery in selected severe cases.
Can keratitis cause vision loss?
Yes, if scarring or deep infection is untreated. Early care greatly improves the outlook.
How can I prevent keratitis?
Practice strict contact lens hygiene, protect eyes from UV and injury, maintain eye-healthy habits, and get regular exams.
Is keratitis contagious?
HSV-related disease can spread in some situations during active infection. Typical bacterial or fungal keratitis is not casually contagious like a cold.
Can children get keratitis?
Yes, from infections or injuries. Parents should seek care promptly for eye pain, light sensitivity, or vision change.
When should I see a doctor?
Immediately for severe pain, sudden vision changes, persistent redness, or coloured discharge—do not wait it out in lens wearers.
Important caution
This article is for general health education only. It is not a substitute for emergency or specialist eye care.
Keratitis treatment must match the cause; only an eye clinician should prescribe therapy.
Seek urgent care for severe eye pain, vision loss, or worsening redness and discharge.