munson's sign munson's sign munson's sign is a v-shaped indentation observed in the lower eyelid when the patient's gaze is directed downwards. the medical sign is characteristic of advanced cases of keratoconus and is caused by the cone-shaped cornea pressing down into the eyelid. munson's signdifferential diagnosiskeratoconus it is named after american ophthalmologist edwin sterling munson (born may 8, 1870 – died feb. 2, 1958).