Herpetic (dendritic) keratitis

What it is

Herpes simplex keratitis is infection of the cornea by herpes simplex virus, usually HSV type 1, of which 90% of the population are carriers. It represents a reactivation of a latent virus which is dormant in the trigeminal ganglion. The dendritic ulcer is HSV epithelial keratitis. The same virus can also cause stromal keratitis, which has a clinical picture like the corneal ulcer.

Causes and risk

Reactivation may be triggered by stress, fever, sun exposure and immunosuppression. So the history looks for a past primary infection such as perioral vesicles, and for a recent immunosuppression or illness. A patient who develops a red eye after immunosuppression is the case to know.

How it presents

Pain, tearing, foreign body sensation and a red eye, and there may be decreased vision and eyelid edema. Examination shows unilateral ciliary congestion with no discharge and reduced VA, and otherwise the cornea seems to be clear. Two signs point to it:

• Corneal hypoesthesia
• A dendritic lesion in the epithelium, thin and branching