[Optimizing the automatic self-tonometer by an acoustic control signal and changed fixation optics].

An automatic self-tonometer must fulfill special requirements from the point of view of precision as well as user-friendliness. The sensor that applanates the cornea must be perfectly centered on the vertex in order to measure the intraocular pressure correctly. The modified version of the self-tonometer has been equipped with an acoustic control signal and a modified fixation lamp that facilitate its use. In order to analyze the effectiveness of these hardware changes, we compared the modified tonometer to the existing self-tonometer in a randomized study with 30 patients. Reference was the Draeger hand-held applanation tonometer. The results show comparable precision; however, the percentage of error measurements in the modified tonometer was considerably lower. This is a definite improvement in the development of the self-tonometer.