Corneal ulceration

Background

  • Corneal ulcers can be very serious if it progresses rapidly.  There is a potential risk of losing the eye.
  • Causes include
    • Bacterial (beware rapid progression with Pseudomonas infection);
      • Commonly caused by Pseudomonas infection that produces proteases andd collagenases which break down the corneal stroma.  It is usually rapidly progressive (over 24 hours).
      • Medical treatment is antibiotics and collagenase inhibitors (acetylcysteine), however, more commonly, surgical corneal transplant is required to retain sight and the eye.
    • viral (herpes simplex (HSV1); varicella zoster);
      • HSV occurs in 1.5/1000/year
    • fungal (candida/aspergillus); protozoal (acanthamoeba)
    • Inflammatory disease (RA; sjogrens, SLE etc)
    • Abrasions, contact lenses (predispose to bacterial infection and trauma), topical steroids
      • Occur in around 5/1000/year (one of the most common encounters in eye emergency departments)

Pathophysiology

  • HSV
    • Theory: either via direct contact or via the trigeminal nerve from oral infection.
      • Initial infection remains asymptomatic then virus travels to establish latent infection (trigeminal ganglion).  Later, particularly during immunocomprimised states, the virus can reactivate along any branch of CN V (inc ophthalmic)

Presentation

  • Pain is usually the main symptom (beware the use of anaesthetic drops).
  • There may be redness of the surrounding sclera/conjunctiva.
  • There may also be a mild loss of visual acuity depending on the degree of corneal involvement BUT normal vision does not exclude the diagnosis.
  • Watery discharge may be present but is usually secondary to the pain (secondary bacterial infection may cause mucopurulent discharge).
  • Ask about history of trauma/grittiness etc
  • On examination
    • The above symptoms may have the appropriate signs.
      • NB It is important to do a full ophthalmological examination (inc eye movements) where there is a history of trauma to exclude other damages
    • Ulcers should be examined with fluorescein stain and UV light
      • NB A dendritic morphology is characteristic of herpes simplex infection
      • A descemetocele is a rare complication of corneal ulceration where the ulcer extends all the way through the stroma.  It appears as a blue ‘crater’ with green ridge.

Management

  • Refer all to ophthalmology
  • HSV is normally a clinical diagnosis (dendritic ulcer)
    • A corneal scrape may be necessary for microbiological investigation where infection (not HSV) is considered
      • It is important to use topical local anaesthetic for this procedure as the cornea is arguably the most sensitive part of the body and any damage can be extremely painful.
  • Topical chloramphenicol should be used for bacterial infection and is often used empirically to prevent secondary bacterial infection
  • Topical aciclovir is the treatment of choice for herpes simplex ulcers.
  • Local anaesthetic drops may be prescribed but may impede healing and are not used long term.
  • Steroid drops should NEVER be used in corneal ulceration.
  • Remove foreign bodies/other causes where possible (only do this where confident to do so)

Prognosis

There is a small tendency for patients with corneal ulcers to recur.  Such ulcers are called refractory or indolent ulcers (sometimes also Boxer’s ulcers.  Treatment for such ulcers often involves antibiotic, anaesthetic and cycloplegic (e.g. atropine) drugs (the latter is to dilate the pupil and thereby stop any spasm of the ciliary muscles in response to pain- this relaxes the eye and reduces symptoms).

Advertisement

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: