Minor Care Series: Corneal Abrasions

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Introduction

The eye is a complicated organ that is not well understood by many new emergency physicians because it historically has not received much attention during medical school.  This makes taking care of these patients challenging.    However, eye complaints make up approximately 8% of ED visits and so it is something we will see quite often.  In this post we will discuss one of the more common etiologies of "eye pain", corneal abrasions.  Corneal abrasions account for 45% of eye complaints in the ED and so are a high yield topic to review.  We will start by reviewing some of the anatomy, and then delve into the presentation and management of these patients.  

Anatomy

Figure 1.  Courtesy of the National Eye institute (6).

The cornea protects the eye by being a barrier.  In adults, it is just over a centimeter in diameter and half a centimeter thick.  It is transparent, avascular, and consists of five layers: epithelium, Bowman's membrane, stroma, descemet's membrane, and endothelium (figure 1).  

Corneal abrasions affect the top layer (epithelium) of the cornea.  The epithelium plays a dual role in being the first barrier to the environment and also has a key role in refracting light, accounting for much of the eye's optical power.  This is why abrasions can sometimes cause visual disturbances.  

The cornea is one of the most sensitive areas of the body because of its heavy innervation.  This innervation is from the ophthalmic branch of the fifth cranial nerve (this acts as the afferent portion of the corneal reflex!).  This heavy innervation is why abrasions can be so painful to the patient.

Presentation

Corneal abrasions are often the result of an object being dragged across the eye.  Examples of this include:

  • Forcefully removing a contact lens that is stuck to the eye
  • Accidental scratching of the eye when rubbing
  • Foreign body under they eyelid irritating the cornea with blinking

Signs and symptoms are variable but will include pain/stinging, foreign body or "gritty" sensation, tearing, redness, and photophobia.  If the abrasion is in the visual axis there may also be some decreased visual acuity.  

Examination

The first step in management is to make the patient more comfortable to allow for a thorough exam.  This is often accomplished with topical anesthesic drops such as tetracaine; apply one to two drops per eye.  These drops will initially cause a burning/stinging sensation but then will lead to pain relief.  Once the patient is comfortable, fully examine the eye looking for areas of redness, foreign bodies, and discolorations in the cornea.  Always compare to the unaffected eye.  In addition, ensure that a pupillary and visual acuity exam is completed for all of these patients.  

Figure 2. Courtesy of Wikimedia Commons (7).

The next step is to perform a fluorescein examination.  Fluorescein is an orange dye, typically adhered to a strip of paper.  This helps to identify abrasions, as the area of abrasion will uptake dye and fluoresce under cobalt blue light.  There are several methods of applying the dye to the eye, none are superior to the others.  One method is to evert the lower lid and apply the fluorescein strip to this area, then ask the patient to blink.  If the patient's eyes are dry, placing a drop of saline or tetracaine to the strip beforehand can help disseminate the dye better.  Another method is to create a "fluorescein solution" by placing the strip in a sterile flush.  The provider can then apply several drops per eye to stain the eye.  

Once the dye is in the patient's eye, use a cobalt blue light (either with a slit lamp or woods lamp) to inspect the eye looking for areas of dye uptake.  Areas of dye uptake are likely abrasions (see image).  The magnification from the slit lamp allows you to visualize smaller abrasions or other defects that may be missed with direct visualization or a woods lamp.  

Management

Many of the treatments that are commonly used for corneal abrasions do not have any scientific validation.  Most providers will prescribe 3 to 5 days of topical antibiotics for all of these patients.  Appropriate antibiotics include erythromycin ointment, trimethoprim/polymyxin drops or sulfacetamide ointment or drops.  None of these are superior to the others and are chosen primarily on provider preference.  

One special consideration is in patients who wear contact lenses.  These patients are often colonized with pseudomonas or other gram negative organisms.  Superinfection can lead to rapid corneal damage and vision loss.  These patient should be prescribed a topical antibiotic that covers pseudomonas.  Appropriate choices for this include ciprofloxacin ointment/solution or oxfloxacin drops.   In addition to antibiotics, these patients should also be told to avoid wearing contact lenses until the abrasion is healed and they are asymptomatic.  If the patient wears contacts that are reused for a period of time, the current contacts should be discarded.

A final consideration is pain control.  As mentioned earlier, the cornea has a high density of nerve endings and so these injuries are incredibly painful.  Oral analgesics such as acetaminophen or NSAIDs are known to work well.  Oral opioids are usually not indicated and should be avoided.  Topical NSAIDs such as ketorolac or diclofenac drops may help relieve pain, but should only be used in uncomplicated abrasions for no more than one to two days to avoid complications.  We recommend only using these drops if you have experience with them, or in consultation with an ophthalmologist.  Topical cycloplegics or mydriatics have been found to provide no benefit in uncomplicated corneal abrasions.

Topical anesthetics have traditionally been avoided after the patient leaves the emergency department despite their effectiveness.  Past evidence on lab animals showed topical anesthetics to have toxic effects on the cornea.  There also have been case reports that showed complications in humans who used high dose, preservative containing formulations.  A double-blind, randomized study in 2014 by Waldman et al evaluated 1% tetracaine vs saline for 24 hours in ED patients with corneal abrasions.  This study found no complications attributed to the topical anesthetic.  Surprisingly, there was also no significant difference in pain ratings, but patients perceived tetracaine to be significantly more effective.  It should be noted that this study focused on uncomplicated abrasions.  Deciding whether or not to prescribe home tetracaine will depend on the injury, patient reliability, and provider comfort.

Flow Chart

Figure 3. Corneal Abrasion Management Flow Chart. 

Pearls

  • Corneal abrasions account for 45% of eye complaints in the ED
  • Use fluoroscein to identify abrasions and a slit lamp to complete a thorough exam
  • Although not evidence based, most patients receive topical antibiotics for 3-5 days
  • Topical tetracaine is likely safe for symptomatic control on discharge, but should be prescribed with caution

Authored by James Li, MD

Edited and Posted by Tim Murphy, MD