Introduction
Keratitis describes inflammation of the cornea. Microbial keratitis is not like conjunctivitis - it is potentially sight-threatening and should therefore be urgently evaluated and treated.
Epidemiology
- Incidence: 20.00 cases per 100,000 person-years
- Peak incidence: 30-40 years
- Sex ratio: 1:1
| Condition | Relative incidence |
|---|---|
| Infective conjunctivitis | 150.00 |
| Corneal abrasion | 15.00 |
| Anterior uveitis | 2.00 |
| Microbial keratitis | 1 |
| Herpes simplex keratitis | 0.70 |
| <1 | 1-5 | 6+ | 16+ | 30+ | 40+ | 50+ | 60+ | 70+ | 80+ |
Aetiology
Causes
- bacterial
- typically Staphylococcus aureus
- Pseudomonas aeruginosa is seen in contact lens wearers
- fungal
- amoebic
- acanthamoebic keratitis
- accounts for around 5% of cases
- increased incidence if eye exposure to soil or contaminated water
- parasitic: onchocercal keratitis ('river blindness')
Clinical features
Features
- red eye: pain and erythema
- photophobia
- foreign body, gritty sensation
- hypopyon may be seen
Referral criteria
Referral
- contact lens wearers
- assessing contact lens wearers who present with a painful red eye is difficult
- an accurate diagnosis can only usually be made with a slit-lamp, meaning same-day referral to an eye specialist is usually required to rule out microbial keratitis
Management
Management
- stop using contact lens until the symptoms have fully resolved
- topical antibiotics
- typically quinolones are used first-line
- cycloplegic for pain relief
- e.g. cyclopentolate
Complications
Complications may include:
- corneal scarring
- perforation
- endophthalmitis
- visual loss