Hello and welcome to the Zero to Finals podcast. My name is Tom and in this episode I'm going to be

talking to you about herpes simplex keratitis. And you can find written notes on this topic at

zero to finals.com slash herpes keratitis or in the ophthalmology section of the second edition of the

0 to finals medicine book. And you can find flashcards and questions to train your knowledge and help

remember the information for longer at members.0.0.5.com. So let's get straight into it.

Keratitis refers to inflammation of the cornea.

The cornea is the outer surface layer that sits in front of the anterior chamber,

iris and pupil at the front of the eye.

There are many causes of keratitis.

Viral infections, for example herpesymplex,

bacterial infection, for example pseudomonas or staphylococcus,

fungal infection, for example candida or aspergillus, contact lens-induced acute red eye,

or Claire, and exposure keratitis caused by inadequate eyelid coverage, for example with ectropion,

where the lower eyelid droops outwards and exposes the eye.

Herpes simplex virus or HSV infection is the most common cause of keratitis, and this is called herpes

simplex keratitis. HSV can cause inflammation of any part of the eye, but most commonly it affects the

epithelial layer of the cornea. Herpesymplex keratitis can be primary or recurrent. Recurrence is

caused by the virus travelling to the trigeminal ganglion, where it becomes latent or dormant,

essentially inactive, and then it can reactivate later.

Herpesymplex keratitis usually affects only the epithelial layer of the cornea.

Inflammation of the stroma, which is the layer between the epithelial layer of the cornea. Inflammation of the stroma, which is the layer between the

epithelium and the endothelium of the cornea, is called stromal keratitis. Stromal keratitis is associated

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