Cornea Infection

Cornea infection, medically known as keratitis, is an inflammation and infection of the cornea, the clear, dome-shaped surface that covers the front of the eye. This condition can be sight-threatening and requires prompt medical attention to prevent permanent vision loss. Corneal infections can be caused by various microorganisms including bacteria, viruses, fungi, and parasites, each requiring specific treatment approaches. Understanding the symptoms, causes, and treatment options is crucial for preserving vision and preventing complications.

Medical Disclaimer: This information is for educational purposes only and should not replace professional medical advice. If you experience sudden eye pain, vision changes, or signs of eye infection, seek immediate medical attention from an eye care professional.

Overview

The cornea is the transparent, dome-shaped tissue that forms the front surface of the eye. It serves as the eye's primary focusing element, contributing approximately 65-75% of the eye's total optical power. The cornea consists of five distinct layers: the epithelium, Bowman's layer, stroma, Descemet's membrane, and endothelium. Each layer has specific functions in maintaining corneal transparency and health.

Corneal infections occur when microorganisms breach the cornea's natural defense mechanisms and establish infection within the corneal tissue. The cornea's normally sterile environment can become compromised due to various factors including trauma, contact lens wear, dry eyes, or immunocompromised states. The type of infection depends on the causative organism and can range from superficial epithelial infections to deep stromal infections that threaten vision.

The incidence of corneal infections varies by geographic location, with higher rates in developing countries due to agricultural injuries, poor hygiene, and limited access to eye care. In developed countries, contact lens-related infections are the most common cause of bacterial keratitis in healthy individuals. Viral keratitis, particularly herpes simplex keratitis, affects approximately 1.5 million people worldwide annually, while fungal keratitis is more common in warm, humid climates and agricultural settings.

Early recognition and treatment of corneal infections are crucial because untreated infections can lead to corneal scarring, perforation, endophthalmitis (infection inside the eye), and permanent vision loss. The prognosis depends on the causative organism, depth of infection, immune status of the patient, and promptness of appropriate treatment. With early diagnosis and proper management, many corneal infections can be successfully treated with minimal long-term visual impact.

Symptoms

Corneal infection symptoms can vary depending on the causative organism, severity of infection, and individual patient factors. Early recognition of symptoms is crucial for prompt treatment and prevention of serious complications.

Primary Ocular Symptoms

Advanced Symptoms

  • Symptoms of eye - general eye discomfort and malaise
  • Foreign body sensation in eye - feeling like something is in the eye
  • Swollen eye - eyelid swelling and periorbital inflammation
  • Photophobia - extreme sensitivity to light
  • Blepharospasm - involuntary eyelid spasms
  • Corneal opacity - cloudiness or whitening of the cornea

Associated Facial Symptoms

  • Lip swelling - may occur in severe infections or allergic reactions
  • Facial numbness or tingling (in viral infections)
  • Headache, particularly around the eye area
  • Facial pain along trigeminal nerve distribution

Bacterial Keratitis Symptoms

  • Rapid onset of severe eye pain
  • Purulent discharge with thick, yellow-green secretions
  • Marked conjunctival injection
  • Corneal infiltrate with surrounding edema
  • Hypopyon (pus in anterior chamber) in severe cases

Viral Keratitis Symptoms

  • Gradual onset of symptoms
  • Vesicular rash on eyelids (in herpes zoster)
  • Dendritic or geographic corneal ulcers
  • Decreased corneal sensation
  • Recurrent episodes in chronic cases

Fungal Keratitis Symptoms

  • Slowly progressive course
  • Moderate pain relative to clinical findings
  • Feathery corneal infiltrate borders
  • Satellite lesions around main ulcer
  • Poor response to bacterial antibiotics

Parasitic Keratitis Symptoms

  • Severe pain out of proportion to clinical findings
  • Ring-shaped corneal infiltrate
  • Characteristic "headlight in fog" appearance
  • History of water exposure
  • Progressive worsening despite treatment

Warning Signs of Complications

  • Sudden worsening of pain
  • Rapid vision loss
  • Corneal thinning or perforation signs
  • Signs of endophthalmitis (deep eye infection)
  • Systemic symptoms like fever or malaise

Causes

Corneal infections result from various microorganisms that can breach the cornea's natural protective barriers. Understanding the different causes helps in appropriate diagnosis and targeted treatment strategies.

Bacterial Causes

Bacterial keratitis is the most common form of infectious keratitis in developed countries:

  • Staphylococcus aureus:
    • Common cause of acute bacterial keratitis
    • Often associated with contact lens wear
    • Can produce virulent toxins
    • May cause rapid corneal destruction
  • Pseudomonas aeruginosa:
    • Aggressive gram-negative organism
    • Strongly associated with contact lens use
    • Produces proteolytic enzymes
    • Can cause rapid corneal melting
  • Streptococcus pneumoniae:
    • Common in elderly patients
    • Often follows corneal abrasion
    • Can spread rapidly through tissue
  • Other bacteria: Serratia, Enterococcus, Haemophilus, Moraxella

Viral Causes

  • Herpes Simplex Virus (HSV):
    • Most common viral cause of keratitis
    • HSV-1 more common than HSV-2
    • Causes epithelial and stromal disease
    • Tends to recur throughout life
    • Can lead to corneal scarring and vision loss
  • Varicella Zoster Virus (VZV):
    • Causes herpes zoster ophthalmicus
    • Follows trigeminal nerve distribution
    • Can cause multiple eye complications
    • More common in immunocompromised patients
  • Adenovirus:
    • Causes epidemic keratoconjunctivitis
    • Highly contagious
    • Often associated with upper respiratory symptoms
    • Can cause subepithelial infiltrates

Fungal Causes

Fungal keratitis is more common in warm, humid climates and agricultural settings:

  • Filamentous fungi:
    • Fusarium species - common in contact lens users
    • Aspergillus species - often from organic matter
    • Penicillium and Acremonium
    • Typically from vegetative trauma
  • Yeast:
    • Candida albicans and non-albicans species
    • More common in immunocompromised patients
    • Often follows bacterial keratitis treatment

Parasitic Causes

  • Acanthamoeba:
    • Free-living amoeba found in water
    • Strongly associated with contact lens use
    • Swimming pools, hot tubs, tap water exposure
    • Extremely difficult to treat
    • Can cause devastating vision loss
  • Microsporidia:
    • Rare but emerging pathogen
    • Often in immunocompromised patients
    • Can cause chronic keratoconjunctivitis

Predisposing Factors

  • Contact lens-related factors:
    • Poor hygiene practices
    • Overnight wear of daily disposable lenses
    • Use of tap water for cleaning
    • Swimming while wearing lenses
    • Extended wear beyond recommended time
  • Ocular surface disease:
    • Dry eye syndrome
    • Meibomian gland dysfunction
    • Trichiasis (misdirected eyelashes)
    • Entropion or ectropion
  • Systemic factors:
    • Diabetes mellitus
    • Immunosuppression
    • Autoimmune diseases
    • Vitamin A deficiency

Environmental and Occupational Factors

  • Agricultural work: Exposure to organic matter and fungi
  • Healthcare settings: Exposure to resistant organisms
  • Swimming and water sports: Exposure to waterborne pathogens
  • Hot tub use: Pseudomonas and Acanthamoeba exposure
  • Tropical climates: Higher fungal keratitis rates

Risk Factors

Multiple factors can increase the risk of developing corneal infections. Understanding these risk factors helps in prevention and early identification of high-risk individuals.

Contact Lens-Related Risk Factors

  • Contact lens wear patterns:
    • Overnight wear increases risk 10-15 fold
    • Extended wear beyond recommended replacement
    • Daily disposable lenses worn multiple days
    • Swimming or showering while wearing lenses
  • Hygiene practices:
    • Poor hand hygiene before lens handling
    • Use of tap water for lens cleaning or storage
    • Inadequate lens case cleaning and replacement
    • Sharing contact lenses with others
  • Environmental exposure:
    • Hot tub use while wearing lenses
    • Swimming in pools, lakes, or oceans
    • Exposure to contaminated water sources
    • Dusty or dirty environments

Ocular Risk Factors

  • Previous eye conditions:
    • History of corneal infections
    • Chronic dry eye syndrome
    • Blepharitis and meibomian gland dysfunction
    • Corneal dystrophies or degenerations
  • Structural abnormalities:
    • Trichiasis (inward-turning eyelashes)
    • Entropion or ectropion
    • Lagophthalmos (incomplete eyelid closure)
    • Corneal scarring from previous injury
  • Ocular trauma:
    • Corneal abrasions from foreign bodies
    • Chemical burns
    • Welding-related UV exposure
    • Sports-related eye injuries

Systemic Risk Factors

  • Immunocompromised states:
    • HIV/AIDS
    • Cancer and chemotherapy
    • Organ transplant recipients
    • Chronic steroid use
    • Autoimmune diseases
  • Metabolic conditions:
    • Diabetes mellitus
    • Thyroid disorders
    • Vitamin A deficiency
    • Malnutrition
  • Age-related factors:
    • Elderly age (decreased immune function)
    • Infancy (immature immune system)
    • Decreased tear production with aging

Occupational and Environmental Risk Factors

  • High-risk occupations:
    • Agricultural workers
    • Construction workers
    • Welders and metalworkers
    • Healthcare workers
    • Laboratory personnel
  • Geographic factors:
    • Warm, humid climates (higher fungal risk)
    • Developing countries (poor hygiene, nutrition)
    • Areas with high UV exposure
    • Regions with endemic infectious diseases

Medication-Related Risk Factors

  • Topical medications:
    • Chronic topical steroid use
    • Preserved eye drops causing toxicity
    • Topical anesthetics (overuse)
    • Contaminated eye drop bottles
  • Systemic medications:
    • Immunosuppressive drugs
    • Chemotherapy agents
    • High-dose systemic steroids
    • Antihistamines causing dry eyes

Behavioral Risk Factors

  • Poor hygiene practices:
    • Inadequate hand washing
    • Sharing eye makeup or tools
    • Using expired cosmetics near eyes
    • Touching or rubbing eyes frequently
  • Lifestyle factors:
    • Smoking (affects immune function)
    • Excessive alcohol consumption
    • Poor nutrition
    • Lack of adequate sleep

Protective Factors

  • Proper contact lens hygiene and care
  • Regular eye examinations
  • Protective eyewear in high-risk environments
  • Good general health and nutrition
  • Prompt treatment of eye injuries
  • Avoidance of known triggers and risk factors

Diagnosis

Accurate and timely diagnosis of corneal infections is crucial for preserving vision and preventing complications. The diagnostic approach combines clinical evaluation, laboratory testing, and sometimes advanced imaging techniques.

Clinical History

Symptom Assessment

  • Onset and progression: Acute vs. chronic, unilateral vs. bilateral
  • Pain characteristics: Severity, quality, and timing
  • Visual symptoms: Degree of vision loss, photophobia
  • Associated symptoms: Discharge, tearing, foreign body sensation

Risk Factor Evaluation

  • Contact lens history: Type, wear patterns, hygiene practices
  • Recent trauma: Corneal abrasions, foreign bodies, chemicals
  • Medical history: Immunosuppression, diabetes, autoimmune disease
  • Environmental exposure: Water activities, agricultural work
  • Previous treatments: Recent eye drops, procedures

Physical Examination

Visual Assessment

  • Visual acuity: Best corrected vision in each eye
  • Pupillary examination: Relative afferent pupillary defect
  • Visual field testing: Confrontation or formal testing
  • Color vision: May be affected in severe infections

External Examination

  • Eyelid inspection: Swelling, redness, vesicles
  • Conjunctival assessment: Injection, chemosis, discharge
  • Preauricular lymph nodes: Enlargement suggesting viral etiology
  • Facial examination: Rash distribution, trigeminal involvement

Slit Lamp Biomicroscopy

  • Corneal epithelium:
    • Epithelial defects, ulcerations
    • Fluorescein staining patterns
    • Rose Bengal staining for devitalized cells
    • Dendritic or geographic patterns (viral)
  • Corneal stroma:
    • Infiltrates and their characteristics
    • Stromal thinning or melting
    • Descemetocele formation
    • Endothelial precipitates
  • Anterior chamber:
    • Cell and flare assessment
    • Hypopyon presence and level
    • Fibrin formation
    • Iris involvement

Laboratory Diagnosis

Specimen Collection

  • Corneal scraping:
    • Multiple samples from ulcer edges and base
    • Use of sterile technique and instruments
    • Avoid contamination from lid margins
    • Collect before empirical treatment when possible
  • Contact lens and case culture:
    • Both lens and storage case
    • Lens solution analysis
    • Environmental water sources if indicated

Microbiological Studies

  • Gram staining:
    • Immediate identification of bacteria
    • Gram-positive vs. gram-negative
    • Presence of inflammatory cells
    • Fungal elements with lactophenol cotton blue
  • Bacterial culture:
    • Blood agar and chocolate agar plates
    • MacConkey agar for gram-negative organisms
    • Incubation at 37°C for 48-72 hours
    • Antibiotic sensitivity testing
  • Fungal culture:
    • Sabouraud's dextrose agar
    • Room temperature incubation
    • Extended incubation period (weeks)
    • Potassium hydroxide (KOH) preparation

Molecular Diagnostics

  • Polymerase Chain Reaction (PCR):
    • Rapid identification of pathogens
    • Especially useful for fastidious organisms
    • Viral detection (HSV, VZV, adenovirus)
    • Acanthamoeba species identification
  • Matrix-assisted laser desorption/ionization (MALDI-TOF):
    • Rapid bacterial and fungal identification
    • High accuracy for common pathogens
    • Results available within hours

Advanced Imaging

Anterior Segment Optical Coherence Tomography (AS-OCT)

  • High-resolution cross-sectional imaging
  • Assessment of corneal thickness and structure
  • Monitoring of treatment response
  • Detection of subclinical changes

Confocal Microscopy

  • In vivo cellular-level imaging
  • Particularly useful for Acanthamoeba detection
  • Assessment of nerve fiber integrity
  • Research and specialized clinical applications

Differential Diagnosis

  • Non-infectious keratitis:
    • Sterile corneal infiltrates
    • Autoimmune keratitis
    • Neurotrophic keratopathy
    • Exposure keratopathy
  • Other ocular conditions:
    • Acute angle-closure glaucoma
    • Anterior uveitis
    • Conjunctivitis
    • Corneal abrasion without infection

Emergency Indications for Immediate Referral

  • Central corneal ulceration
  • Signs of corneal perforation
  • Hypopyon or significant anterior chamber reaction
  • Rapid progression despite treatment
  • Suspected endophthalmitis
  • Inability to identify causative organism

Treatment Options

Treatment of corneal infections requires prompt, targeted therapy based on the identified or suspected pathogen. The goals are to eliminate infection, preserve vision, maintain corneal integrity, and prevent complications.

General Management Principles

  • Immediate measures:
    • Discontinue contact lens wear immediately
    • Avoid eye patching (promotes bacterial growth)
    • Pain management with systemic analgesics
    • Cycloplegia for comfort and to prevent synechiae
  • Monitoring requirements:
    • Daily follow-up for severe infections
    • Assessment of treatment response
    • Monitoring for complications
    • Documentation of ulcer size and depth

Bacterial Keratitis Treatment

Empirical Therapy

Started immediately while awaiting culture results:

  • Broad-spectrum topical antibiotics:
    • Fluoroquinolones (moxifloxacin, gatifloxacin)
    • Combination therapy for severe cases
    • Frequent dosing (every 30 minutes initially)
    • Gradual tapering based on response
  • Severe infections:
    • Fortified antibiotics (cefazolin + tobramycin)
    • Vancomycin for MRSA coverage
    • Systemic antibiotics in deep infections

Culture-Directed Therapy

  • Antibiotic selection: Based on sensitivity results
  • Dosing adjustment: Modify frequency based on response
  • Duration: Continue for 48-72 hours after epithelialization
  • Resistance patterns: Consider local antibiograms

Viral Keratitis Treatment

Herpes Simplex Keratitis

  • Epithelial disease:
    • Topical antivirals (ganciclovir gel)
    • Oral antivirals (acyclovir, valacyclovir)
    • Gentle debridement may be helpful
    • Avoid topical steroids in epithelial disease
  • Stromal disease:
    • Oral antivirals to prevent recurrence
    • Topical steroids with antiviral coverage
    • Long-term suppressive therapy
    • Careful monitoring for progression

Herpes Zoster Ophthalmicus

  • Systemic antivirals: High-dose acyclovir or valacyclovir
  • Oral steroids: May reduce complications if started early
  • Topical steroids: For anterior uveitis
  • Pain management: Including neuropathic pain medications

Fungal Keratitis Treatment

Topical Antifungal Therapy

  • Natamycin 5%:
    • First-line for filamentous fungi
    • Hourly dosing initially
    • Good penetration into stroma
    • May cause epithelial toxicity
  • Voriconazole 1%:
    • Broad-spectrum antifungal
    • Good for Fusarium and Aspergillus
    • Better stromal penetration than natamycin
    • Compounded preparation
  • Amphotericin B 0.15%:
    • Effective against yeasts
    • Limited activity against filamentous fungi
    • Significant epithelial toxicity
    • Reserved for refractory cases

Systemic Antifungal Therapy

  • Indications:
    • Deep stromal infection
    • Scleral extension
    • Endophthalmitis risk
    • Poor response to topical therapy
  • Agents:
    • Oral voriconazole or itraconazole
    • Intravenous amphotericin B for severe cases
    • Duration typically 6-8 weeks minimum

Acanthamoeba Keratitis Treatment

  • Combination therapy:
    • Dual topical agents for synergistic effect
    • Chlorhexidine 0.02% and polyhexamethylene biguanide (PHMB) 0.02%
    • Alternative: propamidine and neomycin
    • Hourly dosing for weeks to months
  • Oral agents:
    • Miltefosine for refractory cases
    • Combination with topical therapy
    • Limited evidence but promising results
  • Surgical debridement:
    • Removal of infected epithelium
    • May improve drug penetration
    • Repeated procedures often necessary

Adjunctive Therapies

Anti-inflammatory Treatment

  • Topical steroids:
    • Controversial in infectious keratitis
    • May be used in viral stromal disease
    • Requires concurrent antimicrobial coverage
    • Can worsen fungal and Acanthamoeba infections
  • Cycloplegia:
    • Relieves ciliary spasm and pain
    • Prevents posterior synechiae
    • Homatropine or cyclopentolate

Supportive Care

  • Artificial tears: Preservative-free formulations
  • Bandage contact lenses: For persistent epithelial defects
  • Therapeutic contact lenses: Drug delivery systems
  • Protective eyewear: During healing phase

Surgical Interventions

Emergency Procedures

  • Corneal gluing:
    • For impending or small perforations
    • Cyanoacrylate adhesive with bandage contact lens
    • Temporary measure until definitive repair
  • Conjunctival flap:
    • For non-healing epithelial defects
    • Provides trophic support
    • May compromise vision

Definitive Surgical Treatment

  • Penetrating keratoplasty:
    • For corneal perforation or severe scarring
    • May be performed acutely or delayed
    • Risk of graft rejection and recurrent infection
    • Visual rehabilitation variable
  • Deep anterior lamellar keratoplasty (DALK):
    • Preserves host endothelium
    • Lower rejection risk
    • Suitable for stromal scarring without endothelial involvement

Management of Complications

  • Corneal perforation:
    • Emergency surgical repair
    • Tissue adhesives for small perforations
    • Patch grafts or full-thickness transplantation
  • Endophthalmitis:
    • Intravitreal antibiotic injection
    • Vitrectomy in severe cases
    • Systemic antibiotics
    • Aggressive anti-inflammatory therapy
  • Secondary glaucoma:
    • Topical antiglaucoma medications
    • Avoid prostaglandin analogs during active infection
    • Surgical intervention may be needed

Prevention

Prevention of corneal infections focuses on eliminating or reducing risk factors, practicing good eye hygiene, and implementing appropriate safety measures. Most corneal infections are preventable through proper precautions and awareness.

Contact Lens Hygiene and Safety

  • Proper hand hygiene:
    • Wash hands thoroughly with soap before handling lenses
    • Dry hands with a lint-free towel
    • Avoid touching the lens tip to any surface
    • Handle lenses with clean fingertips, not fingernails
  • Lens care practices:
    • Use only sterile, commercially prepared lens solutions
    • Never use tap water, saliva, or homemade solutions
    • Replace lens cases every 3 months
    • Clean and air-dry lens cases daily
    • Replace lenses according to prescribed schedule
  • Safe wearing practices:
    • Never sleep in daily disposable lenses
    • Follow prescribed wearing schedules
    • Remove lenses before swimming or showering
    • Remove lenses if eyes become red or painful
    • Never share contact lenses with others

Eye Protection and Safety

  • Occupational safety:
    • Wear appropriate protective eyewear in high-risk environments
    • Use safety goggles in laboratories and industrial settings
    • Implement splash guards when working with chemicals
    • Follow workplace safety protocols
  • Sports protection:
    • Wear protective eyewear during contact sports
    • Use appropriate eye protection for racquet sports
    • Consider sports-specific protective equipment
    • Ensure proper fit and impact resistance
  • Recreational activities:
    • Avoid swimming in contaminated water sources
    • Wear goggles while swimming
    • Be cautious around gardening and yard work
    • Protect eyes from UV radiation

General Eye Hygiene

  • Daily eye care:
    • Avoid touching or rubbing eyes with dirty hands
    • Remove eye makeup thoroughly before bed
    • Replace eye makeup every 3-6 months
    • Don't share eye makeup or applicators
    • Keep fingernails clean and trimmed
  • Environmental considerations:
    • Maintain adequate humidity in living and work spaces
    • Avoid exposure to cigarette smoke
    • Use air filtration systems in dusty environments
    • Be aware of seasonal allergens

Medical Prevention

  • Regular eye examinations:
    • Annual comprehensive eye exams
    • Contact lens follow-up visits as recommended
    • Prompt evaluation of eye injuries or infections
    • Monitoring of chronic eye conditions
  • Management of risk factors:
    • Control diabetes and other systemic diseases
    • Treat dry eye syndrome appropriately
    • Address eyelid abnormalities
    • Manage autoimmune conditions
  • Vaccination:
    • Stay current with recommended immunizations
    • Consider herpes zoster vaccination for appropriate age groups
    • Maintain good overall health and immune function

Education and Awareness

  • Patient education:
    • Understanding proper contact lens care
    • Recognition of early warning signs
    • Knowledge of when to seek medical attention
    • Awareness of personal risk factors
  • Community programs:
    • Eye safety campaigns in schools and workplaces
    • Contact lens safety education
    • Public health initiatives in high-risk areas
    • Healthcare provider education on prevention

Special Populations

  • Immunocompromised patients:
    • Extra vigilance with eye hygiene
    • Avoid high-risk activities
    • Prompt treatment of any eye symptoms
    • Regular ophthalmologic monitoring
  • Healthcare workers:
    • Use of appropriate personal protective equipment
    • Proper handling of contaminated materials
    • Awareness of occupational exposure risks
    • Post-exposure protocols
  • Travelers:
    • Extra contact lens care supplies
    • Avoidance of local water for lens care
    • Access to emergency eye care information
    • Awareness of regional risk factors

When to See a Doctor

Seek emergency care immediately (call 911 or go to emergency room) for:

  • Sudden, severe pain in eye with vision loss
  • Chemical splash or injury to the eye
  • Signs of corneal perforation (clear fluid leaking from eye)
  • Severe swollen eye with fever and systemic illness
  • Complete loss of vision
  • Signs of endophthalmitis (deep eye infection)

Contact an eye care professional urgently (within hours) for:

Schedule an appointment within 24-48 hours for:

  • Persistent lacrimation with discomfort
  • New onset itchiness of eye with vision changes
  • Recurrent eye infections or inflammation
  • Symptoms of eye infection that worsen despite treatment
  • Contact lens intolerance or discomfort
  • History of herpes simplex with new eye symptoms

Routine consultation recommended for:

  • Regular contact lens follow-up examinations
  • Annual comprehensive eye examinations
  • Evaluation after eye injury, even if symptoms resolve
  • Management of chronic dry eye syndrome
  • Diabetic eye examinations
  • Second opinion for complex or recurrent infections

Special situations requiring immediate attention:

  • Contact lens users with any new eye pain or redness
  • Immunocompromised patients with any eye symptoms
  • Patients with history of corneal infections
  • Workers with occupational eye exposure
  • Recent eye surgery patients with new symptoms

Related Conditions

References

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  2. Austin A, Lietman T, Rose-Nussbaumer J. Update on the management of infectious keratitis. Ophthalmology. 2017;124(11):1678-1689.
  3. Konda N, Motukupally SR, Garg P, Sharma S. Microbial analyses of contact lens-associated microbial keratitis. Optom Vis Sci. 2014;91(1):47-53.
  4. Brown L, Leck AK, Gichangi M, Burton MJ, Denning DW. The global incidence and diagnosis of fungal keratitis. Lancet Infect Dis. 2021;21(3):e49-e57.
  5. Lorenzo-Morales J, Khan NA, Walochnik J. An update on Acanthamoeba keratitis: diagnosis, pathogenesis and treatment. Parasite. 2015;22:10.