Keratitis refers to inflammation of the cornea. There are a number of causes of keratitis, mostly infectious. We will discuss viral causes separately (also known as herpes simplex keratitis).
Pathophysiology
Keratitis occurs either due to microbial causes or it can be due to environmental causes. It has the risk of vision loss and needs to be evaluated and treated urgently.
Causes of keratitis can be:
- Bacterial - s. aureus or pseudomonas aeruginosa in contact lens wearers.
- Fungal
- Amoebic - acanthamoebic keratitis if there is eye exposure to soil or contaminated water. The pain is typically out of proportion with the findings.
- Parasitic - onchocercal keratitis/onchocerciasis which is commonly known as African river blindness due to the filarial worm known as onchocerca volvulus.
- Viral - due to HSV (more on this later)
- Environmental - these are not as important in this CCC.
- Exposure keratitis
- Photokeratitis
- Contact lens acute red eye (CLARE)
😷 Presentation
- Red eye
- Painful eye
- Photophobia
- Foreign body or gritty sensation
- Hypopyon can be seen often along with corneal infiltration and opacification.
🔍 Investigations
🏆 Slit-lamp is the only accurate way to diagnose keratitis.
🧰 Management
- Contact lenses - stop wearing until fully resolved.
- 🏆 Topical antibiotics (fluoroquinolones)
- Ciprofloxacin
- Ofloxacin
- Cycloplegics for pain relief (paralysis of ciliary muscle)
- Cyclopentalone
📝 Same-day referral is needed to rule out microbial keratitis.
🚨 Complications
- Corneal scarring
- Perforation
- Endophthalmitis
- Vision loss
HSV is the most common cause of keratitis and it is referred to as herpes simplex keratitis. It can be a primary infection or a recurrent oner
It usually only affects the epithelium of the cornea. However, it can affect the stromal layer (stromal keratitis) which runs the risk of stromal necrosis and blindness.
😷 Presentation
Herpetic keratitis presents with the same problems seen in other forms of microbial keratitis.
🔍 Investigations
- 🏆 Slit-lamp is needed once again.
- ⭐️ Fluorescein staining shows an indicative dendritic corneal ulcer (dendritic as it has branches). Herpes simplex has the dendritic lesion while herpes zoster has small, round ulcers.
- ⭐️ Corneal swabs may be used for a culture or PCR.
🧰 Management
- Topical or oral antivirals:
- Aciclovir - topical or oral.
- Ganciclovir - eye gel.
- Topical steroids can aid the treatment of stromal keratitis when coupled with antivirals.
- Corneal transplant may be required after infection has resolved as a result of the scarring caused by stromal keratitis.