Corneal sensitivity test
Mice were gently immobilized by the scruff in hand. Chemical corneal sensitivity was tested by pipetting 2.5 µl of 2µM capsaicine or 200 µM menthol vertically into the right eye using a micropipette. Blinking times were counted for 30s by experimenter without prior knowledge of surgical or sham. The application of different chemical requires an interval of 15 minutes. Mechanical sensitivity was tested by von Frey filaments of 0.008 g and 0.02 g. Von Frey filaments were applied in the center of each eye five times until slightly bending every five seconds, in the morning and afternoon.