Cochet-Bonnet Esthesiometer (similar to Von Frey Hair) Exam

The Cochet-Bonnet esthesiometer , similar to Von Frey Hair testing, has been used in studies to quantify sensory changes in the trigeminal system, especially the cornea. The device uses a thin fiber to test sensation. The shorter the fiber, the more sensation is felt. The monofilament is applied perpendicular to the surface being tested until it deforms. The patient should respond to at least 2 out of 3 "did they feel it". The process is repeated with stiffer filaments. Each filament is somewhat calibrated. Today, this is rarely used except in experimental situations, sometimes with animals as well as humans.