Corneal Abrasion

1. THE 2-MINUTE PHYSIOLOGY (Rapid Pathophysiology)

• The Mechanism: A corneal abrasion is a mechanical disruption or defect in the epithelial layer of the cornea. Because the cornea is one of the most densely innervated structures in the human body (via the ophthalmic branch of the trigeminal nerve), even microscopic epithelial defects expose superficial nerve endings, resulting in exquisite, severe pain, photophobia, and reactive tearing.
• The Epidemiology: Ocular trauma accounts for 27% of ophthalmic emergencies in the ED, and 73% of this trauma group presents specifically with corneal abrasions.
• Healing Dynamics: The corneal epithelium regenerates rapidly. With appropriate care, uncomplicated abrasions are typically expected to resolve within 1 to 2 days.

2. THE BEDSIDE ACTION PLAN (Rapid ER Management)

• Immediate Assessment: While acute vision loss in isolation is not life-threatening, it is paramount to obtain and document visual acuity as the very first vital sign of the eye before any bright lights, drops, or interventions are applied.
• Analgesia: Instillation of a topical anesthetic (e.g., tetracaine or proparacaine) in the ED provides rapid diagnostic pain relief and facilitates a thorough exam. While home use of topical anesthetics is historically controversial, evidence has shown it to be effective and safe for simple corneal abrasions when combined with close ophthalmology follow-up. Topical nonsteroidal anti-inflammatory drugs (NSAIDs) may also be prescribed for ongoing analgesia.
• First-Line Medications:
• Antibiotics: Topical antibiotic ointments (e.g., erythromycin) are the standard treatment of choice for typical abrasions.
• Contact Lens Wearers: You must include Pseudomonas coverage (e.g., topical ciprofloxacin or ofloxacin) and mandate immediate cessation of contact lens wear.
• Tetanus: Administer tetanus prophylaxis if the patient's immunization status is not up to date.
• Note on Disputed Practices: While some recent literature suggests prophylactic topical antibiotics may not be strictly indicated for all minor abrasions, the consensus strictly dictates that eye patches are not recommended because they create a dark, warm environment that can mask and promote a worsening infection.

3. THE DIAGNOSTIC GRID (Differential Diagnosis & Workup)

Top "Can't-Miss" Differentials:

• Open Globe Injury / Ruptured Globe: Penetrating trauma that breaches the full thickness of the cornea or sclera.
• Bacterial Keratitis (Corneal Ulcer): An active infection of the corneal stroma, especially common in contact lens users, which threatens permanent vision loss.
• Retained Intraocular Foreign Body (IOFB): A foreign body that has penetrated into the globe, requiring admission and operative management.
• Acute Angle-Closure Glaucoma: Presents with eye pain and decreased vision, but features a fixed, mid-dilated pupil and elevated intraocular pressure.

Prioritized Diagnostic Workup:

• Visual Acuity: The mandatory baseline functional test.
• Slit-Lamp Examination: Evaluate the anterior chamber specifically for blood (hyphema) or purulent fluid (hypopyon), which point to severe trauma or deep infection.
• Fluorescein Staining: Use fluorescein dye under a cobalt blue light. The dye pools in areas devoid of epithelium, vividly highlighting the abrasion.
• Eyelid Eversion: You must flip the upper eyelid to inspect the tarsal conjunctiva for hidden foreign bodies.

4. THE VISUAL BOARD (ECG / POCUS / Imaging)

• The "Ice Rink" Sign: The presence of vertical linear corneal abrasions on fluorescein exam is a classic hallmark. It indicates a retained foreign body trapped under the upper eyelid that is scratching the cornea repeatedly with every blink.
• Seidel's Sign: Look for a fluorescent "waterfall" of dye clearing away from a specific point on the cornea. This indicates aqueous humor leaking from a full-thickness laceration, confirming a ruptured globe.
• Pupillary Red Flags: A tear-shaped, irregular, or nonreactive pupil heavily suggests penetrating trauma or globe rupture.
• Imaging: If high-velocity trauma is reported and IOFB is suspected, order a CT of the face/orbits. POCUS is an excellent tool for retinal detachment but requires caution or avoidance if a globe rupture is strongly suspected due to the pressure applied to the eye.

5. THE SCORING MATRIX (Risk Stratification & Guidelines)

• High-Risk Mechanisms: High-velocity injuries (e.g., hammering, grinding metal) carry an extreme risk of penetrating eye injury and intraocular foreign bodies, mandating urgent ophthalmology consultation.
• Disposition Criteria: Simple, uncomplicated corneal abrasions can be discharged with primary ED treatment. However, follow-up for repeat fluorescein testing in 24 to 48 hours must be ensured, particularly for younger patients, those with large abrasions, or abrasions involving the central visual axis.
• Admission Criteria: Any patient with an intraocular foreign body, hyphema, or ruptured globe requires emergent ophthalmologic consultation and admission for operative management.

6. THE DANGER ZONE (Pitfalls & Critical Actions)

• The Tonometry Trap: Do NOT assess intraocular pressure (tonometry) if there is any clinical concern for an open globe injury, as the pressure can cause irreversible extrusion of ocular contents.
• The Patching Trap: Trainees frequently attempt to apply an eye patch for comfort. Eye patching is strictly contraindicated (especially for 48 hours) as it masks worsening infections and delays healing.
• The Retained FB Trap: Never send a patient home with a retained corneal or intraocular foreign body. If a superficial body cannot be removed in the ED, immediate ophthalmology consultation is required prior to discharge.
• Critical Action: Always document the visual acuity, slit-lamp exam, and fluorescein exam findings both before and after any foreign body removal.

7. MCQ MASTERCLASS (Written Exam Tips)

• Buzzword: "Vertical linear abrasions" = Evert the upper eyelid to find the retained foreign body.
• Buzzword: "Tear-shaped pupil" with "collection of blood in the anterior chamber (hyphema)" = Suspect globe rupture.
• Distractor Trap: A question will present a patient with a corneal abrasion who wears contact lenses and offer "patching and erythromycin ointment" as a treatment option. This is incorrect. The correct answer must include cessation of contact lens wear, anti-pseudomonal coverage, and no eye patching.
• Distractor Trap: An MCQ will present a patient with periorbital ecchymosis, a tear-shaped pupil, and hyphema, asking for the next best step. "Tonometry" will be an option. This is a fatal distractor; tonometry must be avoided in suspected open globes.

8. THE BOARDROOM SCRIPT (OSCE & Oral Board Tips)

"My immediate priority is to obtain and document the patient's bilateral visual acuity before applying any bright lights or medications. I will instill topical tetracaine to facilitate a thorough exam. On slit-lamp evaluation, I will look closely at the anterior chamber to rule out hyphema or hypopyon, and check for an irregular pupil that might suggest an open globe. I will apply fluorescein dye under cobalt blue light. If I see vertical linear abrasions, I will immediately evert the upper eyelids to locate and remove any retained foreign bodies. Given the patient wears contact lenses, I will prescribe a topical anti-pseudomonal antibiotic, strictly advise against eye patching or wearing contact lenses, and ensure ophthalmology follow-up within 24 to 48 hours to assess for healing."