PHYSICAL AND AERODYNAMIC AIRSTREAM-PROFIL ES OF THE MICROAIR AESTHESIOMETER CMA

Background In an experimental study we examined the aerodynamical airs treamprofile of a new airstream aesthesiometer. With this instrument i t is possible to measure corneal sensitivity without touching the corn ea. Method A constant hotwire-anemometer was used to measure the 0.5 s air impulse in different distances. The corneal topographic sensitivi ty was measured at 45 probands, age 20 to 80. Results The investigatio ns show that the laminar air stream within the 0.2 mm wide nozzle chan ges after withdrawl, in regards to stream profile, jet width and speed . The parabolashaped stream profile passes over through the air matrix and changes into a bell-shaped profile. The stream properties of the circular free system imply that the air stream in a 4 mm distance is n early half as wide and double as high or fast in comparison to an 8 mm distance. The corneal sensitivity measured with the CMA showed in com parison to the Draeger aesthesiometer a lower sensitivity than in the periphery. Conclusion A clinical use for measuring corneal sensitivity with the CMA can not be recommended.