Superficial Non-Purulent Keratitis.
Keratitis is the inflammation of the cornea. Keratitis can be categorized clinically into: i.
Superficial
- a. Purulent - Bacterial & Fungal
- b. Non-purulent - Viral & Allergic
- ii. Deep
Herpes simplex keratitis - Type 1 herpes simplex (HSV) is a common and important cause of ocular disease. Type 2, which causes genital disease, may occasionally cause keratitis and infantile chorioretinitis. Primary infection by HSV1 is usually acquired early in life by close contact such as kissing. It may be asymptomatic, but otherwise is accompanied by: fever, vesicular lid lesions, follicular conjunctivitis, pre-auricular lymphadenopathy.
Primary infection may cause a conjunctivitis, with or without punctate keratitis. It is followed by resolution and latency of the virus in the trigeminal ganglion.
‘Recurrent’ infection involves reactivation of the latent virus, which travels centrifugally to nerve terminals in the corneal epithelium to cause an epithelial keratitis. There may be no past clinical history. The risk of reactivation is increased if the patient is debilitated (e.g. systemic illness, immunosuppression).
Signs and symptoms - pathognomonic appearance is of a dendritic ulcer. These epithelial ulcers may heal without a scar but they may progress to a stromal keratitis, associated with an inflammatory infiltration and oedema, and ultimately a loss of corneal transparency and permanent scarring.
Diagnosis - immunological tests (immunofluorescence of epithelial scrapings), tissue biopsy and tissue culture (elementary bodies are seen with suitable staining).
Slit-lamp examination of the cornea shows:
- Superficial punctate keratitis - numerous, white plaques of epithelial cells are present all over the corneal surface. These are of minute pinhead size, arranged in rows or groups and absence of vascularization and corneal sensation.
- Dendritic ulcer - erosions coalesce to form typical dendritic figure like liverwort. It is pathognomonic of herpes simplex.
- Confluent ulcer - large geographical pattern type of ulcers are seen.
- Disciform (deep) keratitis - involves the stroma forming disc-like opacity.
Treatment –
- Antiviral drugs – Systemic - oral acyclovir 400 mg twice daily × 7 days. Ideally it should be started prior to the onset of symptoms. It is the method of choice in cases of recurrent herpes labialis. It has low toxicity.