Keratitis: Causes, Symptoms, Diagnosis, Treatment, and Prevention

Introduction

The human eye is one of the most delicate and complex organs, responsible for providing vision and allowing us to interact with the world. The cornea, the transparent outer layer at the front of the eye, plays a vital role in focusing light. However, it is highly vulnerable to infections, trauma, and inflammatory conditions. One of the most common corneal disorders is keratitis.

Keratitis refers to inflammation of the cornea that can result from infections, injury, or underlying systemic diseases. It is a potentially vision-threatening condition if not treated promptly and appropriately. Depending on the cause, keratitis may present with mild discomfort or progress to severe pain, corneal ulceration, scarring, and even blindness.

This article provides a comprehensive overview of keratitis, covering its causes, types, symptoms, diagnostic approaches, treatment options, complications, and prevention strategies.

What is Keratitis?

Keratitis is defined as inflammation of the cornea, which may be infectious or non-infectious. It affects the transparency of the cornea, disrupting vision. The severity can range from superficial involvement of the corneal epithelium to deep stromal damage.

Keratitis is broadly classified into:

Infectious keratitis – Caused by bacteria, viruses, fungi, or parasites.
Non-infectious keratitis – Resulting from trauma, dry eyes, autoimmune conditions, or prolonged contact lens use.

Causes and Risk Factors

1. Infectious Causes

Bacterial keratitis: Often linked to contact lens misuse, trauma, or corneal surface disease. Common organisms include Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus pneumoniae.
Viral keratitis: Frequently caused by herpes simplex virus (HSV) and herpes zoster virus (shingles). Adenoviruses can also cause epidemic keratoconjunctivitis.
Fungal keratitis: Usually follows trauma with organic material (e.g., plant matter). Common fungi include Fusarium, Aspergillus, and Candida species.
Parasitic keratitis: Acanthamoeba keratitis is rare but severe, often associated with contact lens wear and exposure to contaminated water.

2. Non-Infectious Causes

Corneal injury – scratches, foreign bodies, or chemical burns.
Prolonged contact lens wear – especially overnight or poor hygiene.
Dry eye syndrome – inadequate tear production leading to corneal irritation.
Allergic reactions – to eye drops or environmental allergens.
Autoimmune diseases – rheumatoid arthritis, lupus, Sjögren’s syndrome.
Exposure keratitis – due to incomplete eyelid closure (lagophthalmos).

3. Risk Factors

Poor contact lens hygiene
Eye trauma or surgery
Weakened immune system (HIV, diabetes, immunosuppressive therapy)
Long-term corticosteroid eye drop use
Living in warm, humid climates (favorable for fungal keratitis)

Types of Keratitis

Keratitis can be categorized based on cause, appearance, or depth of involvement.

Superficial Keratitis – Affects the top layer (epithelium) of the cornea. Usually heals without scarring.
Deep Keratitis (Stromal Keratitis) – Involves deeper corneal layers; may lead to scarring and vision loss.
Ulcerative Keratitis – Associated with corneal ulceration, often due to bacteria, fungi, or parasites.
Interstitial Keratitis – A non-suppurative form, often linked to syphilis, tuberculosis, or autoimmune disease.
Neurotrophic Keratitis – Results from loss of corneal sensation, commonly caused by HSV infection or nerve damage.

Symptoms

Keratitis may present suddenly or develop gradually, depending on the underlying cause. Common symptoms include:

Eye pain or discomfort
Redness of the eye
Excessive tearing (epiphora)
Blurred or reduced vision
Sensitivity to light (photophobia)
Sensation of a foreign body in the eye
Discharge from the eye (watery, mucopurulent, or thick)
Swelling of the eyelids
White or gray spots visible on the cornea (in ulcerative keratitis)

If untreated, symptoms may worsen, leading to complications like corneal perforation or permanent blindness.

Diagnosis

A prompt and accurate diagnosis is essential for effective treatment. Diagnostic methods include:

History and Clinical Examination
- Assessment of symptoms, contact lens use, recent trauma, systemic diseases.
- Slit-lamp examination to evaluate corneal inflammation, ulceration, or infiltrates.
Microbiological Tests
- Corneal scraping/culture: Identifies bacterial, fungal, or parasitic organisms.
- Polymerase Chain Reaction (PCR): Detects viral DNA, particularly for HSV or VZV.
Staining Techniques
- Fluorescein stain: Highlights corneal epithelial defects under cobalt blue light.
- Gram stain and KOH prep: Help detect bacteria and fungi.
Imaging
- Confocal microscopy: Useful in diagnosing Acanthamoeba keratitis.
- Anterior segment OCT: Provides detailed images of corneal layers.

Treatment Options

The treatment of keratitis depends on its cause and severity. Prompt intervention is critical to preserve vision.

1. General Measures

Discontinuation of contact lenses during treatment.
Frequent use of preservative-free artificial tears.
Eye protection to avoid further trauma.

2. Antimicrobial Therapy

Bacterial keratitis: Broad-spectrum topical antibiotics (fluoroquinolones like moxifloxacin, gatifloxacin). Severe cases may require fortified antibiotics or systemic therapy.
Viral keratitis: Antiviral eye drops (trifluridine, ganciclovir) or oral antivirals (acyclovir, valacyclovir). Corticosteroids may be cautiously used under supervision in stromal keratitis.
Fungal keratitis: Antifungal eye drops (natamycin, amphotericin B, voriconazole). Severe cases may require systemic antifungal therapy.
Parasitic keratitis (Acanthamoeba): Combination of topical antiseptics (polyhexamethylene biguanide, chlorhexidine) for prolonged durations.

3. Anti-inflammatory Therapy

Topical corticosteroids may be used with caution in non-infectious keratitis.
Non-steroidal anti-inflammatory drugs (NSAIDs) for pain relief.

4. Surgical Options

Debridement: Removal of infected or necrotic corneal tissue.
Corneal transplantation (keratoplasty): Required in severe cases with scarring, perforation, or non-healing ulcers.
Amniotic membrane transplantation: Promotes healing in resistant keratitis.

Complications

If untreated or poorly managed, keratitis can lead to:

Corneal scarring
Corneal perforation
Secondary glaucoma
Endophthalmitis (severe eye infection)
Permanent vision loss or blindness

Prevention

Since many forms of keratitis are preventable, preventive strategies are crucial:

Contact Lens Hygiene
- Wash hands before handling lenses.
- Use sterile solutions for cleaning and storage.
- Avoid sleeping or swimming with contact lenses unless approved.
Eye Protection
- Wear safety glasses to prevent trauma or chemical exposure.
Good General Health
- Control systemic diseases like diabetes.
- Maintain a strong immune system through proper nutrition and lifestyle.
Prompt Medical Attention
- Seek immediate care for eye pain, redness, or vision changes.
Vaccination
- Shingles vaccine reduces risk of herpes zoster keratitis.

Global and Public Health Perspective

Keratitis is a major cause of corneal blindness, second only to cataract and glaucoma in some regions.
Bacterial keratitis is more common in developed countries due to high contact lens use.
Fungal keratitis is prevalent in tropical and subtropical regions, often linked to agricultural trauma.
In low-resource settings, delayed diagnosis and lack of access to antifungal or antiviral medications lead to high rates of blindness.
Public health initiatives focusing on education, access to eye care, and affordable treatments are essential to reduce keratitis-related blindness.

Future Directions in Research

Novel antimicrobials: Development of new antibiotics, antifungals, and antivirals to combat resistant strains.
Nanotechnology-based drug delivery: Enhancing penetration and sustained release of medications.
Stem cell therapy: For corneal surface reconstruction.
Artificial cornea (keratoprosthesis): As an alternative to donor corneas in severe cases.
AI-assisted diagnosis: Use of artificial intelligence in analyzing slit-lamp and confocal images for early detection.

Conclusion

Keratitis is a significant eye disorder that can severely compromise vision if not diagnosed and treated promptly. It can result from a variety of infectious and non-infectious causes, with contact lens misuse, trauma, and systemic diseases being common risk factors.

Effective management involves early diagnosis, appropriate antimicrobial therapy, and, in severe cases, surgical intervention. However, prevention through proper eye care, contact lens hygiene, and timely medical consultation remains the most effective strategy.

With advancements in diagnostics, therapeutics, and public health awareness, the burden of keratitis-related blindness can be significantly reduced. Ultimately, protecting the cornea means protecting vision — one of the most valuable senses humans possess.

Health Lines

Thursday, August 28, 2025