Keratitis

see also Corneal Ulcer

Keratitis is an inflammation of the cornea which may or may not be associated with an infection. There are many causes of keratitis and careful questioning of the patient should be undertaken to try and identify what may have led to the condition.

There are also subtypes of Keratitis mentioned in the literature – usually dependant on the areas affected:

• Keratoconjunctivitis – affects cornea & conjunctiva
• Kerato-uveitis – affects cornea, iris, ciliary body & choroid
• Superficial keratitis – limited to the corneal epithelium
• Stromal keratitis or interstitial keratitis – affecting epithelium and deeper stromal layer of cornea.
• Mucous plaque keratitis – sign of herpes zoster infection
• Nummular Keratitis – caused by viral keratoconjunctivitis
• Neurotrophic keratitis – this is caused when the innervation to the cornea ceases to function properly. This reduces sensitivity and reflex tearing and therefore corneal injury may go unnoticed. It can be associated with multiple sclerosis, herpes zoster, herpes simplex and also chronic overuse of some glaucoma drops such as timolol and betaxolol.

• Herpetic disciform keratitis – stromal and epithelial oedema surrounds by round (disciform) area of keratic precipitates

Signs/Symptoms:

• Red eye
• Pain/discomfort
• Drop in vision
• Discharge
• Photophobia
• Lacrimation
• Cells and flare in anterior chamber
• Staining visible with Fluorescein

Marginal keratitis – a corneal ulcer is visible as a white patch outlined in the photo in the 5 o’clock position. Note also associated sectorial redness in this area.

Causes:

  • Infection-
    • Bacterial – Pseudomonas aeruginosa and Staphylococcus aureus are the most commonly identified bacterial causatives. Often linked to inappropriate use of contact lenses. Pseudomonas aeruginosa can be particularly devastating to corneal integrity.
    • Viral – herpes simplex virus (dendritic keratitis) can lead to a dendritic ulcer (see corneal ulcer section of A-Z). Herpes zoster. Adenoviral infections and other viruses responsible for the common cold.
    • Acanthamoeba – linked to infected water supplies, swimming, spas and an association with contact lens wear in these conditions
    • Fungal – Aspergillus, Candida albicans, or Fusarium. Linked to outdoor activities such as gardening and also incorrect/ inadequate cleaning of contact lenses.
    • Other parasitic – included for reference only as very rare in the developed world however may affect people returning from exotic travel – Onchocerca volvulus caused by infected blackfly bite- the so called River Blindness is the most well-known.
  • Non-infectious –
    • Compromised Immune function-rheumatoid arthritis, Sjogren’s, HIV etc
    • Dry eye
    • Abnormalities of lid
  • Injury –
    • Trauma,
    • Chemical injury

Treatment:

Detailed questioning, slit lamp examination and possible referral for further tests including the taking of cultures may need to be undertaken before treatment can be commenced. Treatment will be dependant on the type of keratitis and may include, but not be limited to the following:

Infectious Keratitis:

  • Anti-fungal eye drops and oral antifungal medication
  • Anti-bacterial eye drops for mild cases- more severe cases may require oral antibiotics
  • Anti-viral and oral anti-viral medication. Lubricants
  • Parasitic /Amoebic-Antiseptic drops- polyhexamethylene biguanide, Chlorhexidine, Brolene or Hexamidine, which have an anti-amoebic effect

Non-infectious

  • Lubricants
  • For severe cases patching and topical eye medication

Injury

  • Trauma – dependant on severity – from lubricants to surgical intervention
  • Chemical Injury – repeated irrigation to reduce ph to normal and then emergency referral

 

Red Flags:

  • Pain – severe or moderate pain that is no better with analgesics
  • Drop in vision
  • Nausea
  • Acute red eye

When one or more of these red flags is raised, a conversation with another registrant in practice should take place following which appropriate referral or management should be actioned and noted. If there are no other registrants in practice then contact should be made with colleagues elsewhere or contact should be made for advice to the local Hospital Eye Service.