Keratitis (Corneal Inflammation)

Keratitis is inflammation of the cornea—the clear, dome-shaped surface that covers the front of the eye. It can be caused by infections (bacterial, viral, fungal, parasitic), injury, dry eyes, or autoimmune conditions. Infectious keratitis, especially when associated with a corneal ulcer, is a sight-threatening emergency requiring prompt treatment.

Types of Keratitis

Infectious Keratitis

Bacterial Keratitis:

• Most common infectious type in contact lens wearers
• Common organisms: Pseudomonas, Staphylococcus, Streptococcus
• Can progress rapidly to corneal ulcer
• Requires aggressive antibiotic treatment

Viral Keratitis:

• Herpes simplex keratitis—most common
• Herpes zoster (shingles) keratitis
• Adenoviral keratitis
• Each has specific treatment

Fungal Keratitis:

• Often after plant/organic material injury
• Fusarium, Aspergillus, Candida
• Slower progression than bacterial
• Harder to treat, prolonged therapy needed

Parasitic Keratitis:

• Acanthamoeba keratitis—water exposure, especially with contact lenses
• Very difficult to treat
• Associated with contaminated water/contact lenses

Non-Infectious Keratitis

Exposure Keratitis:

• From incomplete eyelid closure (Bell's palsy, thyroid eye disease)
• Cornea dries and breaks down

Neurotrophic Keratitis:

• Loss of corneal sensation
• Poor healing
• Secondary to nerve damage (herpes, surgery, diabetes)

Autoimmune/Inflammatory:

• Peripheral ulcerative keratitis
• Associated with rheumatoid arthritis and other conditions
• Marginal keratitis

Contact Lens-Related:

• Sterile infiltrates
• Tight lens syndrome
• Can progress to infectious

Risk Factors

Contact Lens Wear

Other Risk Factors

• Previous eye surgery (LASIK, transplant)
• Eye trauma
• Severe dry eye
• Blepharitis
• Compromised immune system
• Steroid eye drop use
• Previous herpes eye infection
• Eyelid abnormalities

Symptoms

Warning Signs

Symptom Patterns by Type

Type	Pain	Discharge	Other Features
Bacterial	Severe	Purulent	Rapid onset
Viral (HSV)	Moderate	Watery	Recurrent, decreased sensation
Fungal	Variable	Variable	Slower onset, after plant injury
Acanthamoeba	Severe (out of proportion)	Variable	Water/lens exposure

Diagnosis

Clinical Examination

• Visual acuity
• Slit lamp examination (essential)
• Corneal staining with fluorescein
• Assessment of infiltrate size, depth, location
• Check for hypopyon (pus in anterior chamber)
• Corneal sensation (decreased in herpes)

Laboratory Studies

For significant infiltrates:

• Corneal scraping for culture
• Gram stain
• Fungal stains and cultures
• Acanthamoeba testing if suspected
• HSV testing if indicated

Imaging

• OCT may show depth of involvement
• Confocal microscopy can help identify organisms (especially Acanthamoeba)

Treatment

Bacterial Keratitis

Empiric Treatment (Before Culture Results):

• Broad-spectrum topical antibiotics
• Fluoroquinolone drops (moxifloxacin, gatifloxacin) for mild to moderate
• Fortified antibiotics (cefazolin + tobramycin) for severe
• Frequent dosing initially (every 1-2 hours)

Adjustments:

• Based on culture results
• Clinical response

Viral Keratitis (Herpes Simplex)

• Antiviral treatment (oral and/or topical)
• Trifluridine drops or ganciclovir gel
• Oral acyclovir or valacyclovir
• No steroids for epithelial disease (makes it worse)
• Steroids carefully used for stromal disease (with antiviral cover)

Fungal Keratitis

• Antifungal drops (natamycin, voriconazole, amphotericin B)
• Prolonged treatment (weeks to months)
• Often requires oral antifungals
• May need surgical intervention (debridement, possibly transplant)

Acanthamoeba Keratitis

• Combination of anti-amoebic drops
• PHMB (polyhexamethylene biguanide), chlorhexidine
• Treatment for months
• Often severe and prolonged
• May ultimately need corneal transplant

Supportive Care

• Cycloplegic drops (reduce pain)
• Oral pain medication
• Discontinue contact lens wear
• Close follow-up (daily initially for severe cases)

Complications

Potential Outcomes

• Corneal scarring—may obstruct vision
• Corneal perforation—if untreated or severe
• Endophthalmitis—infection spreads inside eye
• Vision loss—permanent if not treated promptly
• Need for corneal transplant

Prevention

For Contact Lens Wearers

Essential Practices:

• Never sleep in contact lenses
• Never swim or shower in lenses
• Never use tap water with lenses
• Replace lenses on schedule
• Use proper disinfection
• Wash hands before handling lenses
• Replace lens case regularly

General Prevention

• Treat underlying conditions (dry eye, blepharitis)
• Protect eyes from injury
• Don't share eye drops
• Seek prompt care for any eye injury or symptoms

Frequently Asked Questions

Can keratitis cause blindness?

Yes, untreated infectious keratitis can cause permanent vision loss. This is why prompt treatment is so important. The outcome depends on the cause, severity, and how quickly treatment begins.

How long does keratitis take to heal?

Healing time varies greatly:

• Mild bacterial: days to weeks
• Severe bacterial: weeks
• Fungal: weeks to months
• Acanthamoeba: months to years
• Viral: variable, may recur

When can I wear contacts again?

Only after complete healing and clearance from your doctor. You'll typically need to wait weeks after the infection resolves. Use fresh lenses and a new case. Some patients are advised not to return to contact lens wear.

What's the difference between keratitis and conjunctivitis?

• Keratitis: inflammation of the cornea (clear front surface)
• Conjunctivitis (pink eye): inflammation of the conjunctiva (membrane covering white of eye) Keratitis is generally more serious and vision-threatening.

Can keratitis come back?

Some types, especially herpes simplex keratitis, can recur. Preventive measures (ongoing antiviral medication) may be recommended for recurrent cases.

References