[Physical and aerodynamic airflow relations of the air stream of the Micro-Air aesthesiometer].

BACKGROUND

In an experimental study we examined the aerodynamical airstreamprofile of a new airstream aesthesiometer. With this instrument it is possible to measure corneal sensitivity without touching the cornea.

METHOD

A constant hotwire-anemometer was used to measure the 0.5 s air impulse in different distances. The corneal topographic sensitivity was measured at 45 probands, age 20 to 80.

RESULTS

The investigations show that the laminar air stream within the 0.2 mm wide nozzle changes after withdrawal, 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 nearly 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 comparison 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.