Keratitis: Symptoms, Types, Causes and Treatment

Keratitis is a potentially sight-threatening condition that affects the cornea—the clear, dome-shaped window at the front of the eye. Whether caused by infections, injury, or underlying health problems, keratitis demands timely recognition and effective management to preserve vision. This article explores keratitis in detail, synthesizing the latest research to help you understand its symptoms, types, causes, and treatment options.

Symptoms of Keratitis

Recognizing keratitis early can make a significant difference in outcomes. The symptoms often overlap with other eye conditions but tend to be more severe and persistent, warranting prompt medical attention.

Symptom	Description	Severity	Source(s)
Redness	Persistent redness of the eye	Moderate–High	7 8
Pain	Ranges from mild discomfort to severe pain	Moderate–High	7 8
Tearing	Excessive watering or discharge	Moderate	7 8
Blurred Vision	Difficulty seeing clearly	High	7 8 11
Light Sensitivity	Discomfort in bright light	Moderate	7 8
Inflammation	Swelling of the cornea and surrounding tissue	Variable	7 8 11

Table 1: Key Symptoms

Understanding the Symptoms

Keratitis can develop suddenly or gradually. The hallmark symptoms are usually more pronounced than those of simple eye irritation or conjunctivitis.

Redness and Pain

• The affected eye often appears red due to increased blood flow and inflammation.
• Pain can range from a gritty, foreign body sensation to severe, stabbing discomfort, especially in infectious cases 7 8.

Tearing and Discharge

• Increased tear production is common as the eye attempts to flush out irritants or pathogens.
• Discharge may be watery or, in bacterial cases, thick and pus-like.

Visual Disturbances

• Blurred vision is a warning sign that the corneal surface is being disrupted, either by infection, inflammation, or scarring 7 8 11.
• Some patients may notice halos around lights.

Light Sensitivity (Photophobia)

• Bright environments can become intolerable.
• This symptom is particularly common in viral and severe bacterial keratitis.

Inflammation

• Swelling of the cornea, eyelids, and surrounding tissues may occur.
• Severe inflammation can threaten the structure and clarity of the cornea, risking permanent vision loss.

Types of Keratitis

Keratitis is not a single disease, but a spectrum of conditions grouped by cause and clinical presentation. Knowing the type is crucial for selecting the right treatment.

Type	Causative Agent or Mechanism	Typical Features	Source(s)
Bacterial	Bacteria (e.g., Staph, Pseudomonas)	Rapid onset, pus, ulceration	7 8 13
Fungal	Filamentous or yeast-like fungi	Feathery edges, satellite lesions, slow response	1 4 5 6
Viral	HSV, VZV, others	Dendritic ulcers, recurrent	3 11
Parasitic	Acanthamoeba, others	Severe pain, ring infiltrate	2 7 8 11
Non-infectious	Trauma, dry eye, autoimmune	Depends on underlying cause	8 11

Table 2: Main Types of Keratitis

Infectious Keratitis

Bacterial Keratitis

• Common Causes: Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcus pneumoniae 7 8 13.
• Features: Rapid progression, pus, corneal ulcer, often linked to contact lens use or trauma 8 13.
• Severity: Can cause severe vision loss if untreated.

Fungal Keratitis

• Agents: Fusarium, Aspergillus, Candida, among others 1 4 5 6.
• Features: Feathery-edged infiltrates, satellite lesions, poor response to antibiotics, worse outcomes than bacterial 4 5 6.
• Risk Factors: Trauma (especially with plant matter), chronic eye disease, corticosteroid use, contact lenses 1 4 5.

Viral Keratitis

• Viruses: Herpes simplex virus (HSV) is most common, followed by varicella-zoster virus (VZV) 3 11.
• Features: Dendritic (branching) ulcers, recurrent episodes, can be superficial or deep (stromal) 3 11.
• Complications: Scarring, recurrent bouts, risk of permanent vision loss.

Parasitic Keratitis

• Agents: Acanthamoeba, particularly in contact lens wearers 2 7 8 11.
• Features: Severe pain often out of proportion to clinical findings, ring-shaped infiltrates 2 7 8.
• Treatment: Challenging; often requires prolonged therapy.

Non-infectious Keratitis

• Causes: Trauma, dry eye, exposure, immune-mediated diseases 8 11.
• Features: Vary depending on cause; may mimic infectious keratitis.

Causes of Keratitis

Understanding what triggers keratitis is vital for effective prevention and management. The causes range from infections to physical and chemical injuries, and even immune system problems.

Cause	Key Example(s)	Risk Factors or Context	Source(s)
Microbial	Bacteria, Fungi, Viruses, Parasites	Contact lenses, trauma	1 2 7 8 9
Trauma	Plant material, foreign bodies	Outdoor work, accidents	1 4 5 8
Contact Lens Use	Improper hygiene, extended wear	Young adults, poor cleaning	2 8
Ocular Surface Disease	Dry eye, lid disease	Aging, autoimmune disorders	8 11
Surgery	Post-ocular procedures	Recent surgery	5 8 11
Immunosuppression	Steroid use, systemic disease	Medications, disease states	1 5 8 11

Table 3: Major Causes and Risk Factors

Microbial Causes

Bacterial

• Most common in developed countries.
• Associated with contact lens wear, ocular trauma, or pre-existing eye disease 7 8.

Fungal

• More prevalent in tropical or developing regions.
• Often follows trauma with plant matter; can occur after corticosteroid or contact lens use 1 4 5 6.

Viral

• HSV is the leading cause in developed nations.
• Recurrence is common; can be triggered by stress, illness, or immunosuppression 3 11.

Parasitic

• Acanthamoeba keratitis is especially linked with improper contact lens hygiene and exposure to contaminated water 2 7 8.

Non-microbial Causes

Trauma

• Direct injury disrupts the corneal surface, making infection more likely 1 4 5.
• Small, unrecognized injuries (e.g., from plant material) are often the starting point for fungal keratitis.

Contact Lens Use

• Major risk factor for bacterial, fungal, and Acanthamoeba keratitis 2 8.
• Risks increase with overnight wear, poor hygiene, or swimming with lenses.

Ocular Surface Disease

• Dry eye, lid abnormalities, and chronic surface disease compromise corneal defenses 8 11.

Surgery and Immunosuppression

• Recent eye surgery or use of topical/systemic steroids can increase susceptibility 1 5 8 11.

Treatment of Keratitis

Effective treatment of keratitis hinges on rapid diagnosis and tailored therapy. The approach varies depending on the underlying cause, with new technologies and drug delivery systems offering hope for improved outcomes.

Treatment Modality	Indication/Type	Notes/Highlights	Source(s)
Topical Antibiotics	Bacterial keratitis	Fluoroquinolones, fortified antibiotics, resistance a concern	2 8 11 13
Antifungal Agents	Fungal keratitis	Natamycin (first-line), voriconazole, amphotericin, slow response	1 4 5 6 11
Antivirals	Viral keratitis	Acyclovir, ganciclovir, corticosteroids for stromal disease	3 11
Anti-parasitic Agents	Acanthamoeba	Prolonged therapy, challenging	2 11
Surgery	Severe/refractory cases	Penetrating keratoplasty, therapeutic graft	1 4 5 11
Adjunct Therapies	Severe inflammation	Corticosteroids (select cases), novel drug delivery (contact lenses, PDT)	10 11 12

Table 4: Treatment Approaches

Bacterial Keratitis

• First-line: Broad-spectrum topical antibiotics (e.g., fluoroquinolones) until cultures identify the specific pathogen 2 8 11 13.
• Resistance: Rising resistance, especially among Staphylococcus and Pseudomonas species, makes culture and sensitivity testing essential 8 13.
• Adjuncts: Corticosteroids may help in certain severe cases but must be used cautiously 11.

Fungal Keratitis

• First-line: Topical natamycin (especially for Fusarium); voriconazole is preferred for non-Fusarium cases 1 4 5 6 11.
• Other options: Amphotericin B, newer delivery systems (e.g., hydrogel contact lenses loaded with voriconazole) show promise for refractory cases 10.
• Surgery: Frequently required in deep or unresponsive infections—therapeutic keratoplasty (corneal transplant) 1 4 5 11.

Viral Keratitis

• First-line: Topical and/or oral antivirals (e.g., acyclovir for HSV) 3 11.
• Stromal disease: Addition of corticosteroids is beneficial in select cases but must be closely monitored 11.
• Prevention: Long-term oral antivirals can reduce recurrence risk 11.

Parasitic Keratitis

• Agents: Acanthamoeba keratitis needs prolonged anti-parasitic therapy (e.g., polyhexamethylene biguanide, chlorhexidine) 2 11.
• Challenges: Often resistant to standard therapies; early diagnosis is critical.

Adjunct and Emerging Therapies

• Photodynamic Therapy (PDT): Used in refractory or resistant cases to enhance microbial killing 4 12.
• Innovative Drug Delivery: Drug-eluting contact lenses and nanoplatforms are under investigation to improve efficacy and reduce side effects 10 12.
• Immunomodulation: Targeting the host immune response may help limit corneal damage 11 12.

Surgical Interventions

• Penetrating Keratoplasty: Full-thickness corneal transplant for persistent infection or structural damage 1 4 5 11.
• Other procedures: Debridement or localized excision may help in select cases.

Conclusion

Keratitis is a complex, vision-threatening condition with diverse causes and clinical presentations. Early recognition, precise diagnosis, and targeted therapy are essential for preserving sight. Research continues to improve diagnostic tools and treatments, offering hope for better outcomes in the future.

Key Takeaways:

• Symptoms include redness, pain, tearing, blurred vision, and photophobia—prompt attention is vital 7 8 11.
• Keratitis can be bacterial, fungal, viral, parasitic, or non-infectious—correct identification guides therapy 1 2 3 4 5 6 7 8 11.
• Major causes include infections, trauma, contact lens use, ocular surface disease, surgery, and immunosuppression 1 2 4 5 7 8 11.
• Treatment is tailored to the cause; options include topical antibiotics, antifungals, antivirals, anti-parasitics, innovative drug delivery systems, and surgery for severe cases 1 2 4 5 6 8 10 11 12 13.
• Advances in diagnostics and therapy—such as molecular testing, drug-eluting lenses, and photodynamic therapy—are improving patient outcomes.

If you experience symptoms of keratitis, seek prompt ophthalmic evaluation—timely intervention can make the difference between full recovery and permanent vision loss.