Multiple parallel-line endotheliitis--a form of herpes simplex keratitis?

To report a case of multiple parallel-line endotheliitis with a possible link to herpes simplex virus.

An 89-year-old woman presented with new onset reduced vision in her left eye. Her visual acuity with pinhole was 20/120 with the affected eye and 20/30 in the right. She had a white left eye with significant corneal edema and keratic precipitates. These were arranged in a striking pattern of multiple parallel lines resembling railroad tracks. She responded very well to topical steroid and was found to have positive immunoglobulin G and immunoglobulin M titers for herpes simplex virus.

Multiple parallel-line endotheliitis may represent a mild expression of herpes simplex keratitis. It appears to be exquisitely sensitive to topical steroid on its own suggesting that immune response has a dominant role in its pathogenesis.