HERPES SIMPLEX KERATITIS

Herpes Simplex Keratitis is the most common corneal virus infection. It is caused by herpes
simplex virus and is manifest as a dendritic, (branching) staining figure in the corneal epithelium.
This is high-lighted by staining with Bengal Rose 1% which shows dead epithelial cells, or
Fluorescein 1% which stains breaks in the corneal epithelium.

Symptoms are:
- photophobia
- irritation
- lacrimation
- and blurred vision if the cornea is affected.
There is a tendency for dendritic ulcer to lead to a deep stromal type of keratitis known
as Disciform Keratitis. The grey central infiltration of the cornea is caused by antibody-antigen
reaction within the stromal layer of the cornea. Recurrences are common and iritis is frequent.
If the lesion becomes necrotic, hypopyon and perforation of the cornea may occur.

(i) Dendritic Ulcers
Treatment:
(a) Debridement - topical anaesthetic drops are instilled, and loose epithelium containing much
virus is wiped off.

(b) Antiviral Medication - several agents are currently available in this country -
(i) Idoxuridine (Stoxil, herplex)
(ii) Vidarabine (VIRA - A)
(iii) Acyclovir (Zovirax)

These drugs interfere with the growth of the herpes simplex virus, but often are toxic in their
effect to the cornea and should only be used for a short duration.

(c) Antibacterial Cover - a broad spectrum antibiotic eye drop may also be used.

(d) Mydriatic - drops to dilate the pupil may be used to prevent posterior synechiae which
may result because of the associated uveitis.

(e) Cycloplegic drops may also be used to immobilize the ciliary muscle and to rest the
eye and relieve pain.

(f) Sunglasses or eye pad may be required to diminish photophobia.

(ii) Disciform Herpetic Keratitis is usually an excessive immune reaction.
Steroids are administered to diminish this reaction, but they must be used under strict
medical supervision or they may lead to extensive ulceration or perforation of the cornea.
Treatment may be prolonged.