Herpes eye infection (herpes simplex keratitis)

For a lay person:

Herpes simplex keratitis is an infection of the clear front surface of the eye (the cornea) by the cold sore virus. It usually affects one eye, often comes back, and repeated attacks can scar the cornea and permanently reduce vision.

For a trained medical person:

Caused by primary or reactivated herpes simplex virus type 1, presenting as epithelial dendritic ulcers, stromal keratitis or endotheliitis. Diagnosis is by slit-lamp examination with fluorescein staining showing dendrites, with PCR where uncertain. Treatment is topical or oral antivirals such as aciclovir, with ophthalmologist-supervised topical steroids for stromal disease and long-term oral antiviral prophylaxis for recurrences.

In Chinese medicine:

Liu and Tseng's textbook differentiates this condition into these patterns: Wind-Heat Attacking Eye; Damp-Heat Accumulation and Steaming; Zheng Qi Deficiency and Residual Evil Pathogens; Zheng Qi Deficiency with Blood Stasis. Treatment follows the pattern a patient presents with, not the Western diagnosis alone.

When to get help: A painful red eye with blurred vision or light sensitivity needs same-day assessment by an eye specialist. Do not use steroid eye drops unless an eye doctor prescribes them, as they can worsen herpes infection; Chinese medicine is adjunctive at most.