Clinical Practice and Cases in Emergency Medicine

Keratoconus is a progressive disorder affecting the cornea, which causes the cornea to become weakened and conical in appearance. The resultant decrease in structural integrity of the cornea predisposes affected individuals to acute corneal hydrops, a break in Descemet’s membrane, the deepest layer of the cornea, resulting in pain and acute vision loss. We present here a case of this little-known cause of acute vision loss, and an example of Munson’s sign, which is a v-shaped protrusion of the lower eyelid on downward gaze that is characteristic of advanced keratoconus. We hope to highlight Munson’s sign as a simple identifier of keratoconus in an otherwise undiagnosed individual suspected of having acute corneal hydrops.