Editing Keratitis (section)

===Viral===
[[File:Dendritic corneal ulcer.jpg|thumb|right|Dendritic corneal ulcer after fluorescein staining under cobalt blue illumination]]
[[File:Adenoviral keratitis.jpg|thumb|Adenoviral keratitis of a 24-year-old woman]]

The most common causes of viral keratitis include [[herpes simplex virus]] (HSV) and [[varicella zoster virus]] (VZV), which cause [[herpes of the eye|herpes simplex keratitis]] and herpes zoster keratitis (a subtype of [[herpes zoster ophthalmicus]]) respectively.<ref name="Durand 2023" /> Herpes simplex keratitis occurs due to latent HSV reactivation in the [[ophthalmic nerve]] (the V1 branch of the [[trigeminal nerve]]).<ref name="Durand 2023" /> Herpes keratitis is classically associated with a branching (dendritic) infiltrate pattern of inflammation in the corneal epithelium and may cause clouding of the cornea.<ref name="Durand 2023" /> 

Approximately 8-20% of cases of [[shingles]] (due to VZV reactivation) involve the eyes as herpes zoster ophthalmicus.<ref name="Mohammed 2021">{{cite journal |last1=Mohammed |first1=Taariq K |last2=Cohen |first2=Elisabeth J |last3=Jeng |first3=Bennie H |title=A Review of Treatment for Herpes Zoster Keratitis |journal=US Ophthalmic Review |date=2021 |volume=15 |issue=2 |pages=43 |doi=10.17925/USOR.2021.15.2.43|doi-access=free }}</ref><ref name="Durand 2023" /> And VZV keratitis occurs in 13-76% of cases of herpes zoster ophthalmicus, usually 1 month after onset of symptoms.<ref name="Durand 2023" /> Herpes zoster ophthalmicus is also associated with reactivation of ZVZ in the V1 branch (the ophthalmic nerve) of the trigeminal nerve.<ref name="Mohammed 2021" /> VZV keratitis presents as a dendriform epithelial keratitis pattern early in the course of the infection.<ref name="Mohammed 2021" /> ZVZ keratitis may cause clouding of the cornea, with 50% of cases involving inflammatory infiltrates in the [[stroma of cornea|stromal layer of the cornea]], corneal scarring is a possible complication of VZV keratitis.<ref name="Durand 2023" /> Vaccination with the [[zoster vaccine]] is highly effective in preventing shingles, as well as herpes zoster ophthalmicus and herpes zoster keratitis.<ref name="Durand 2023" />