Herpes Simplex Keratitis

Question 1

Aetiology

Answer 1

HSV can affect:
Eyelid and conjunctive -> blepharoconjuncitvitis
Cornea -> keratitis
Uvea -> anterior uveitis
Retina -> acute retinal necrosis.

Can be primary or recurrent. Primary is spread with direct contact with active lesions or their secretions. After infection, HSV lays latent in trigeminal ganglion. Recurrent when there is reactivation of the virus.

HSV1 - above waist, affecting mucous membranes such as lips, face, eyes.
HSV2 - below waist, sexually acquired

HSK leading cause of blindness in UK. Categorised based on the corneal layer affected e.g. epithelial, stromal or endothelial

Question 2

Predisposing factors

Answer 2

Poor general health, stress, fatigue, immunosuppression

Systemic or topical steroids

Aggravating factors - sun, extreme temperatures, infection, trauma,

Severe atopy

Hx of viral infection

Question 3

Symptoms

Answer 3

Pain - discomfort, irritation, burning
photophobia
redness
watering
blurred vision

Question 4

non pharmacological management

Answer 4

sunglasses for photophobia

dilated fundoscopy to rule out viral retinitis e.g. peripheral infiltrates, vasculitis, vitritis, intra retinal haemorrhages

Question 5

Signs

Answer 5

Spectrum of disease entities with differing management

EPITHELIAL
- punctate lesions which coalesce into dendriform pattern, dendritic ulcer with end bulbs that stain with NaFl.
- reduced corneal sensitivity
- mild AC inflammation
- amoebic or geographic ulcer with inappropriate steroid use
- scarring and corneal haze after resolution

STROMAL
- stromal infiltrates, oedema, neovascularisation, opacification which leads to reduced vision
- can be non-necrotising (localised oedema, self-limiting) or necrotising (widespread inflammation)

ENDOTHELIAL
- Central or eccentric zone of epithelia oedema over stromal thickening.
- Folds in Descemet’s membrane, raised IOP, KPs.

METAHERPETIC
- most severe form.
- recurrent HSV attacks, bullous keratopathy, anterior uveitis

Question 6

pharmacological

Answer 6

if adult, non-CL wearer, confined to epithelium - acute or recurrent, commence following treatment:

GANCICLOVIR 0.15% 5X/DAY FOR 1 WEEK. Review in 1 week. If cornea healed, 3X/DAY for 1 WEEK then STOP.

ACICLOVIR 3%, 1cm ribbon into eye at 4 hourly intervals. Review weekly. After resolution, continue for another 3 days before stopping.

IF NO BETTER AFTER 1 WEEK, REFER URGENTLY.

SAME DAY REFERRAL IF child, CL wearer, stromal involvement, bilateral.

Question 7

management at hospital

Answer 7

Swabs or biopsy to confirm virus.
PCR for HSV DNA
Antivirals - oral or topical
Topical steroids - for stromal or endothelial cases
Anti-glaucoma meds if IOP raised

Epithelial debridement: removal of infected epithelium
Keratoplasty (penetrating or lamellar): in quiescent cases with scarring