Central corneal ulcers are local epithelial defects with underlying corneal tissue degradation or inflammation. Common causes include bacterial and fungal infections related to contact lens use or exposure. Diagnosis involves history, exam noting epithelial loss and infiltrate size/density, and corneal cultures. Treatment begins with frequent topical fluoroquinolone or fortified antibiotics based on culture results. Referral is needed if unable to culture, no response to treatment, progressive lesion, or atypical infiltrate. Daily follow up is required until the lesion stabilizes, indicated by epithelial healing and resolution of symptoms and signs of infection.

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Compiled by Dr. Iddi Ndyabawe
Question:
Discuss the management of corneal ulcers
CENTRAL CORNEAL ULCERS
BASICS
DESCRIPTION
• Local epithelial defect with degradation or inflammation of underlying tissue
• Synonyms: Corneal infiltrate, infectious or noninfectious keratitis
EPIDEMIOLOGY
lncidence
Bacterial keratitis
• 30,000 cases annually in the United States
• 10--30 cases per 100,000 of contact lens wearers per year (United States)
Generally, in temperate climates most corneal infections are bacterial and are frequently related to
contact lens use although reports of recent increases in fungal keratitis in the UK have been reported.
Conversely, fungal rates from African and Asian studies were high ranging at an average of 50%.
Specifically, regardless of geographical location, Gram positive organisms (Streptococcus
pneumoniae, Staphylococcus aureus) and Gram-negative pathogens (Pseudomonas aeruginosa) are the
most frequent bacterial causes while Fusarium spp and Aspergillus spp are the most common fungal
causes. However, in temperate climates, Candida spp have been commonly reported.
Prevalence
• Varies greatly geographically
• Secondary variable is etiology
RISK FACTORS
• Contact lens use
• Compromised host factors: Ocular surface disease
• Inadequate eyelid closure or apposition
• Corneal hypoesthesia
• Systemic autoimmune diseases (less likely to be central)

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GENERAL PREVENTION
• Contact lens hygiene
• Preventing compromise of epithelium
• Sufficient lubrication
• Surgical correction of eyelid abnormalities
• Control of acute inflammatory state in autoimmune diseases
PATHOPHYSIOLOGY
• Breakdown of epithelium
• Marked inflammatory response: Leukocyte infiltration (usually neutrophils)
• Degradation of extracellular matrix: Prolonged activation of plasmin, matrix metalloproteinase
secretion
ETIOLOGY
• Infectious: Bacterial, fungal, viral, acanthamoeba
• Noninfectious/sterile: Neurotrophic, autoimmune related, corneal exposure (inadequate eyelid closure)
COMMONLY ASSOCIATED CONDITIONS
• Infectious ulcer: Contact lens abuse/overwear trauma
• Neurotrophic keratitis: VII nerve palsy, herpes simplex, herpes zoster
• Sterile ulcer: Rheumatoid arthritis, systemic lupus erythematosus, Wegener's granulomatosis, Sjogren's
syndrome
• Exposure keratopathy: Thyroid orbitopathy
~ DIAGNOSIS
HISTORY
• Elicit comprehensive history of contact lens wear if applicable including extended vs daily wear,
storage/disinfecting methods, swimming with lenses, exposure to any source of water, including tap
water, lake, pond, etc.
• Recent trauma to the ocular surface including acid/alkali burn
• History of dry eyes
• Comprehensive review of systems (especially autoimmune diseases)
PHYSICAL EXAM
• Eyelid examination to determine adequate closure apposition, trichiasis
• Conjunctival injection
• Tear film insufficiency

3. 3
• Epithelial loss (fluorescein staining)
• Density and size of stromal infiltrate
• Thinning of stromal tissue
• Anterior chamber cell and flare
• Hypopyon
DIAGNOSTIC TESTS & INTERPRETATION
Lab
Initial lab tests
• Corneal cultures: Scrapings obtained from border of infiltrate and placed on specific culture media
• Can use Kimura spatula or moistened calcium alginate swab
• Blood agar: Aerobic bacteria (S. aureus, epidermidis, S. pneumoniae, P. aeroginosa), saprophytic
fungi, Nocardia
• Chocolate agar: Aerobic and facultative bacteria W. gonorrhea, H. influenzae, Bartonella)
• Thioglycollate broth: Aerobic, facultative, anaerobic bacteria
• Thayer-Martin agar: Neisseria
• Lowenstein-Jensen agar: Mycobacteria, Nocardia
• Non-nutrient agar with f. coli overlay: Acanthamoeba
Follow-up and special considerations
• Central ulcers should be cultured prior to starting topical antibiotics.
• Also culture if ulcer is nonresponsive to topical antibiotics
Imaging
Slit lamp photography can document size and density of infiltrate.
Diagnostic Procedures/Other
• Special stains include gram stain (bacteria), Giemsa stain (Chlamydia, Acanthamoeba, Acid-fast stain
(Myrobacteria), Calcofluor white (A.canthamoeba)
• Corneal biopsy if unresponsive to treatment
• Confocal microscopy (Acanthamoeba)
DIFFERENTIAL DIAGNOSIS
• Gram positive: S. aureus, Coagulase Negative Staph. Streptococcus pneumoniae, Srreptococcus
viridians, Corynebacterium diphtheriae. PropionibadMum. Mycobacterium, Bad/Ius cereus
• Gram negative: Pseudomonas, Serratia, Proteus mirabilis, H. influenzae, Moraxella, Neisseria

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• Fungal: Candida, Fusarium, Aspergllus, Curvularla, Mucor, Rhizopus
• Acanthamoeba
• Neurotrophic keratitis
• Herpes simplex keratitis
• Exposure keratopalt1y
• Autoimmune diseases (primary peripheral corneal ulcer): Rheumatoid arthritis, Systemic Lupus
Erythematosus (SLE), Wegener's granulomatosis, collagen vascular diseases
TREATMENT
MEDICATION
First line
• 4th-generation fluoroquinolone: 1drop every 15 min for the 1st hout then per hour around the dock
• 4th generation: Moxifloxacin, gatifloxacin, besfloxacin
• Others: Ciprofloxacin, levofloxacin 1.5%
• For severe or nonresponsive infiltrate: Fortified topical antibiotics can be prepared by the pharmacy.
• Fortified vancomycin 25-50 mg/ml combined with fortified tobramycin/gentamicin 9-14 mg/ml or
combined with fortified ceftazidime 50 mg/mL
• Regimen can be modified according to culture results/susceptibility testing.
Second line
• If unresponsive and culture negative consider acanthamoeba, fungal keratitis, atypical organisms.
• Acanthamoeba: Topical ophthalmic Neospotin, PHMB, hexamidine, chlorhexidine
• Fungal keratitis: Topical natamycin 5%, amphotericin B, imidazoles (voriconazole, ltraconazole,
ketoconazole, clotrimazole, fluconazole)
• Non-tuberous mycobacteria: Amikacin/clarithromycin 20-40 mg/ml
• Nocardia: Amikacin 2Q-40 mg/ml
Additional treatment
General Masures
• Cycloplegic agent helps with pain and prevents synechiae: Homatropine 5% b.i.d., isopto-hyosdne
0.25% t.i.d., atropine 1% q.i.d.
• Topical ointment or gel at bedtime:
Ciloxan/erythromycin/bacitracin ointment, azithromycin (viscous drop)

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Issues for Referral
Refer to cornea specialist if:
• Unable to culture
• Unresponsive to treatment (24-48 h)
• Progressive lesion
• Atypical infiltrate
Indications for admission
• Severe infection hypopyon, purulent exudate, or
complicated disease.
• Poor compliance likely: either with administering drops or returning for daily review.
• Other concern: only eye, failing to improve, etc.
Additional Therapies
• Systemic antibiotics for Neisseria
• Systemic anti-fungals for Acanthamoeba
ONGOING CARE
FOLLOW-UP RECOMMENDATIONS
• Daily follow-up until lesion is stabilized
• Criteria of stabilization: Healing of overlying epithelium, resolution of hypopyon, decrease in density
of infiltrate, no further thinning of cornea, improvement in visual acuity, symptomatic improvement.