keratitis
keratitis
Introduction
- keratitis is inflammation of the cornea and may be caused by a variety of mechanisms:
- bacterial - including Pseudomonas
- a major issue in the immunocompromised, diabetic or those wearing contact lenses
- amoebic
- viral
- “Christmas eye”
- an incredibly painful monocular keratitis usually involving 90% of the epithelium (often punctate corneal ulcers becoming large geographic ulcers) affecting those in NE Victoria and SW NSW in summer as a result of exposure to the chemical pederin which is produced the crushing of certain types of small beetle (up to 1cm) in the eye when they crawl in there and are rubbed or blinked, or the toxin is rubbed into the eyes from your hands - usually of the genus Paederus (Staphylinidae) or genus Orthoperus (Corylophidae). They can also cause severe dermatitis starting 12-36hrs after skin contact (prevent by washing ASAP with soap and water after suspected contact) and the so-called 'whiplash' stripe across the skin which may last up to 3 weeks. Pederin is a strong inhibitor of protein biosynthesis and it is a blistering agent. Generally occurs only between late October and early March. Most resolve with supportive care as per keratitis but some can scar.
- traumatic
- allergic
- dry eyes
- impaired blinking (eg. unconscious patient, Bell's palsy, etc)
- impaired tear production (eg. acne rosacea, keratoconjunctivitis sicca, etc)
Herpetic keratitis
- caused by Herpes simplex virus (HSV)
- recurrent HSV is the leading cause of blindness due to corneal issues requiring corneal transplant in Western societies
- it is usually unilateral but may be bilateral
- 3 main types
- epithelial type
- incubation period 1-28 days
- initial infection may be subclinical or may present as conjunctivitis
- clinical presentations are generally of eye pain, tearing, red eye and photophobia and slit lamp examination with flourescein staining may reveal the classic dendritic ulcers, or the later, deeper and larger geographic ulcers
- Immune herpetic stromal keratitis
- an inflammatory reaction to the virus particles in a deeper layer of the cornea
- usually presents following the initial infection as a recurrence but presents with similar symptoms as epithelial type
- Necrotizing stromal keratitis
- the most severe form
- usually only occurs after patient has already had several recurrences of herpetic keratitis
- virus destroys the corneal tissue and causes an inflammatory reaction and may lead to perforation
- diagnosis
- clinical examination with slit lamp +/- PCR swab
- treatment
- specialist assessment is advisable as each type requires different treatment
- EARLY ORAL antivirals such as fancicyclovir
- avoid topical antivirals as these may cause further corneal damage
- some types also need topical steroids
keratitis.txt · Last modified: 2023/01/03 10:12 by gary1