Corneal Ulcers: Everything You Need to Know

Corneal Ulcer: A - Z Guide

Definition

A corneal ulcer is an open sore or defect on the cornea, the clear, dome-shaped surface that covers the front of the eye. It often occurs due to an infection, trauma, or underlying eye condition. Corneal ulcers are a serious condition that can threaten vision if not promptly treated.

Types of Corneal Ulcers

1. Based on Etiology

• A. Infectious Corneal Ulcers

• Bacterial: Common organisms include Staphylococcus aureus, Pseudomonas aeruginosa, and Streptococcus pneumoniae. Features: Purulent discharge, hypopyon.
• Fungal: Common organisms include Aspergillus, Fusarium, and Candida. Features: Dry, feathery margins, satellite lesions.
• Viral:
  • Herpes Simplex Virus (HSV): Dendritic or geographic ulcers, reduced corneal sensation.
  • Herpes Zoster Ophthalmicus (HZO): Vesicular rash, pseudodendrites.
• Protozoal: Acanthamoeba. Associated with contact lens use, radial keratoneuritis.
• Chlamydial: Associated with trachoma and inclusion conjunctivitis.

• B. Non-Infectious Corneal Ulcers

• Neurotrophic Keratitis: Impaired corneal innervation, commonly due to HSV, diabetes, or trauma.
• Exposure Keratopathy: Inadequate lid closure, as seen in facial palsy or ectropion.
• Allergic or Immune-Mediated: Mooren's ulcer, peripheral ulcerative keratitis (PUK).
• Chemical or Toxic Injuries: From alkalis, acids, or drugs.

2. Based on Morphology

• Dendritic Ulcer: Seen in HSV infection.
• Geographic Ulcer: Enlarged dendritic ulcer, also in HSV.
• Ring Ulcer: Common in Acanthamoeba or fungal infections.
• Shield Ulcer: Associated with vernal keratoconjunctivitis.
• Peripheral Ulcer: Often seen in autoimmune conditions (e.g., rheumatoid arthritis).

3. Based on Depth

• Superficial Ulcer: Involves the epithelial layer only.
• Deep Ulcer: Extends into the stromal layer, may lead to perforation.

4. Based on Location

• Central Ulcer: Affects the visual axis, significant visual impact.
• Paracentral/Peripheral Ulcer: May occur due to systemic diseases or marginal keratitis.

5. Special Types

• Marginal Keratitis: Hypersensitivity reaction to staphylococcal antigens.
• Mooren's Ulcer: Idiopathic, painful, peripheral ulceration, often bilateral.
• Terrien’s Marginal Degeneration: Non-inflammatory thinning of the peripheral cornea.
• Interstitial Keratitis: Seen in syphilis, tuberculosis, or viral infections.

Causes

• Infections:
  • Bacterial infections: Common in contact lens users.
  • Viral infections: Herpes simplex virus (HSV) or varicella-zoster virus (shingles).
  • Fungal infections: Often caused by plant material injury or in people using prolonged corticosteroids.
  • Parasitic infections: Acanthamoeba, often associated with poor contact lens hygiene.
• Trauma: Eye injuries from foreign bodies, scratches, or chemical burns.
• Dry Eye Syndrome: Reduced tear production increases the risk of corneal damage and infection.
• Contact Lenses: Overuse, poor hygiene, or wearing them overnight.
• Underlying Conditions:
  • Vitamin A deficiency.
  • Eyelid disorders causing poor closure (e.g., lagophthalmos).

Signs and Symptoms

• Severe eye pain.
• Redness and swelling in the eye.
• Sensitivity to light (photophobia).
• Blurred or reduced vision.
• Discharge from the eye.
• A white or gray spot on the cornea visible to the naked eye.
• Excessive tearing.
• A sensation of a foreign body in the eye.

Diagnosis

• Clinical Examination: Using a slit lamp to assess the corneal lesion.
• Patient History: Noting recent trauma, contact lens use, or systemic illnesses.
• Fluorescein Staining: A dye is applied to the eye to highlight the ulcer under blue light.
• Culture and Sensitivity Tests: Samples from the corneal surface are analyzed to identify infectious agents.
• Additional Tests:
  • PCR for viral causes.
  • Confocal microscopy for parasitic infections.

Investigations

• Corneal scraping for microbial analysis.
• Complete blood count (CBC) to detect systemic infections.
• Tear film analysis for dry eye evaluation.
• Imaging: Ultrasound biomicroscopy if the view of the cornea is obscured.

Treatment

1. Medical Management

• Bacterial Ulcers: Broad-spectrum antibiotics: Moxifloxacin, Ciprofloxacin, or Tobramycin.
• Fungal Ulcers: Natamycin 5% or Voriconazole drops.
• Viral Ulcers: Acyclovir ointment or oral Acyclovir (for herpes).
• Parasitic Ulcers: Polyhexamethylene biguanide (PHMB) or Chlorhexidine.

2. Supportive Treatment

• Cycloplegic eye drops (e.g., Atropine) to relieve pain and prevent complications.
• Artificial tears to maintain hydration.

3. Medications to Avoid

• Corticosteroids: Contraindicated in fungal and certain bacterial infections as they may worsen the condition.

Role of Vitamins

• Vitamin A: Essential for corneal health and epithelial repair. Deficiency can cause keratinization and ulcers.
• Vitamin C: Promotes collagen synthesis and aids in corneal wound healing.

Complications

• Corneal scarring leading to vision impairment.
• Perforation of the cornea.
• Endophthalmitis: Severe infection of the interior of the eye.
• Loss of the eye in extreme cases.

Management

1. Preventive Measures

• Practice good contact lens hygiene.
• Avoid eye trauma and foreign body exposure.

2. Surgical Options

• Corneal Transplant: In cases of severe scarring or perforation.
• Amniotic Membrane Grafts: For promoting healing in non-infectious ulcers.

3. Regular Follow-ups

• To monitor healing and prevent recurrence.

4. Patient Education

• Emphasize the importance of early treatment and adherence to therapy.