Corneal Trauma

Introduction to Corneal Trauma - Eye's Shield Under Siege

The cornea, the eye's transparent "shield," is vital for vision and protection. Trauma to this structure is common and potentially sight-threatening.

• Types of Corneal Injuries:

  • Mechanical:
    • Abrasions: Superficial epithelial defect.
    • Lacerations: Partial/full-thickness (penetrating/perforating).
    • Foreign Bodies: Superficial or intraocular.
    • Blunt Trauma: Contusion, globe rupture.
  • Non-Mechanical:
    • Chemical Burns: Acid/Alkali (⚠️ Alkali more severe).
    • Radiation Keratitis: e.g., UV exposure.

• Common Patient Presentation:

  • Severe pain, foreign body sensation.
  • Photophobia, lacrimation.
  • Blurred vision.
  • Redness (circumciliary injection).
  • History of trauma.

⭐ Alkali chemical burns penetrate deeper into ocular tissues via saponification, causing more extensive damage than acid burns.

Mechanical Corneal Injuries - When Things Go Bump (or Sharp!)

• Common Types:
  • Corneal Abrasion: Superficial epithelial defect; intense pain.
  • Foreign Body (FB): Superficial/embedded; rust ring if metallic.
  • Laceration: Partial/full-thickness (penetrating/perforating).
• Key Symptoms: Sudden pain, photophobia, lacrimation, FB sensation, ↓vision.
• Essential Signs:
  • Fluorescein staining: Highlights epithelial defects (abrasions, entry sites).
  • Visible FB: On cornea or under lids (evert lids!).
  • Seidel's Test: Positive in perforation (aqueous leak dilutes fluorescein - "waterfall" sign).
  • Other: Conjunctival injection, AC reaction, hyphema, irregular pupil.
• Management Principles:
  • Abrasion: Topical antibiotics, cycloplegic, analgesia. Patching controversial.
  • FB: Removal (needle/spud), rust ring removal (burr), antibiotics.
  • Laceration: Shield eye (NO patch), urgent surgical repair.

⭐ A peaked pupil often points towards the site of a corneal perforation.

Chemical Corneal Burns - The Alkali-Acid Agony

• Alkali Burns (More Severe):
  • Agents: Lime ($Ca(OH)_2$), $NaOH$, $NH_3$.
  • Mechanism: Saponification, ↑penetration. Liquefactive necrosis.
  • Prognosis: Worse. 📌 ALKALI is AWFUL.
• Acid Burns (Less Severe):
  • Agents: $H_2SO_4$, $HCl$.
  • Mechanism: Protein coagulation, ↓penetration. Coagulative necrosis.
  • Exception: Hydrofluoric acid ($HF$) - acts like alkali.
• Clinical: Pain, ↓vision, corneal opacity, limbal ischemia (key prognostic factor).
• Grading (Roper-Hall): I-IV based on corneal clarity & limbal ischemia.
  • Grade IV: Opaque cornea, >50% limbal ischemia.
• Management:
  • Immediate: Copious irrigation (>30 mins with saline/water).
  • Medical: Ascorbate, citrate, doxycycline, steroids (cautiously).
  • Surgical: Amniotic Membrane Transplant (AMT), Limbal Stem Cell Transplant (LSCT).

⭐ Alkali burns cause liquefactive necrosis, leading to deeper penetration and more severe, progressive damage compared to the coagulative necrosis of most acid burns which tends to be self-limiting.

Diagnosis, Management & Complications - Patching Up the Pane

• Diagnosis:

  • History: Mechanism of injury (blunt, sharp, chemical, radiation).
  • Slit-lamp examination: Vital for assessing depth, extent, foreign bodies.
  • Fluorescein staining: Highlights epithelial defects (abrasions, ulcers).
  • Seidel’s test: Detects aqueous leak (globe perforation).
  • Imaging: B-scan (posterior segment), CT scan (intraocular foreign body, orbital fracture).

• Management Principles:

  • Remove foreign bodies.
  • Topical antibiotics: Prophylaxis/treatment (e.g., Moxifloxacin).
  • Cycloplegics: (e.g., Homatropine, Cyclopentolate) for pain relief, prevent synechiae.
  • Pressure patching/Bandage contact lens: For large abrasions.
  • Tetanus prophylaxis.
  • Surgical repair: For full-thickness lacerations.
  • Chemical burns: Copious irrigation (📌 LITMUS test first! Saline/Ringer's lactate).

• Complications:
  • Infection (corneal ulcer, endophthalmitis).
  • Corneal scarring, opacification.
  • Irregular astigmatism.
  • Traumatic cataract, glaucoma.
  • Sympathetic ophthalmia (rare).

⭐ Seidel’s test is crucial for identifying full-thickness corneal lacerations by observing fluorescein dye dilution from leaking aqueous humor under cobalt blue light.

High‑Yield Points - ⚡ Biggest Takeaways

• Corneal abrasions: fluorescein stain positive; treat with topical antibiotics, cycloplegics.
• Seidel's test (streaming fluorescein) confirms corneal perforation.
• Penetrating injuries: rigid shield (no patch), systemic antibiotics, urgent referral.
• Chemical burns: copious, prolonged irrigation crucial; alkali burns more severe.
• Corneal foreign bodies: prompt removal, antibiotic cover; check for rust ring.
• Hyphema (blood in AC) often indicates significant blunt trauma.
• Suspect intraocular foreign body (IOFB) with high-velocity or penetrating trauma.