Comparison of measurement results of multiple transfer standards in different non-contact tonometers

The non-contact tonometer transfer standard is an eye-like design that simulates the human eye's response to the airflow and light beam emitted by the non-contact tonometer. The rubber eye, one of the most commonly used transfer standards, is currently available in two structural designs: discrete and adjustable. In this paper, 4 kinds of rubber eyes made by different manufacturers were tested on 10 different models of non-contact tonometers. The results showed that except one model could not be tested with rubber eyes, the measurement values of the other 9 models of non-contact tonometers had large dispersion and low consistency, whether discrete or adjustable rubber eyes are used. Therefore, it is unscientific to assign a fixed reference pressure value to the transfer standard to verify various models of non-contact tonometers. The determination of the reference pressure value should be further studied to ensure the accuracy of the measurement results of the non-contact tonometer.