Cochet-Bonnet Aesthesiometer

Several methods are available to measure comeal sensitivity " The Cochet-Bonnet aesthesiometer with a filament producing mechanical stimuli, warming the cornea with a jet of warm saline, chemical stimulation of the cornea with e.g. capsaicin, thermal stimulation of the cornea with a carbon dioxide laser, air-impulse aesthesiometry, and stimulation with a low electric current. In most experiment animal and human studies the Cochet-Bonnet aesthesiometer was used. ... 

Therefore, in the present studies measurement of the corneal sensitivity was performed with the Cochet-Bonnet aesthesiometer in experimental animals as well as in humans. The aim was to detect anesthetizing properties of Azelastine Eye Drop solutions and to evaluate the relevance for the treatment in man. 

As in experimental animals also in human volunteers the Cochet-Bonnet aesthesiometer was used. The sensation was measured in the inferior cornea at the 6 o clock position. The quantification of the corneal sensitivity was achieved by determination of the length of the fibre, which was necessary to provoke a notification from the subject. The corresponding pressure in g/mm was recorded. 

During measurement of the corneal sensitivity with the Cochet-Bonnet aesthesiometer in both albino and pigmented rabbits the pressure base values for untreated, physiological saline solution treated, or vehicle solution treated animals was approximately 5 g/mm. In Beagle dogs the mean pressure to elicit a blink reflex was higher than in rabbits and reached approximately 9 g/mm. In human volunteers, where the subjective notification of the touch of the filament tip on the cornea was taken as criterion, pressure base values were much lower than in experimental animals, i.e. approximately 1 g/mm. ... 

Aesthesiometry using the Cochet-Bonnet aesthesiometer is a reliable method for measuring the comeal sensitivity during preclinical studies with medicinal products for topical application to the eye. 

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