Evaluation and testing of novel ocular tactile tonometry device

Abstract

This article describes the experimental analysis of a novel trans-scleral tonometer based on the use of multiple force sensors forming a mechanical stiffness sensor. This approach is similar to an instrumented form of digital palpation tonometry in which manual palpation is used to conclude the stiffness, and hence, the intraocular pressure of the eye. Force data obtained from these probes correlate with the intraocular pressure (IOP) of the eye. Enucleated porcine eyes were used to validate the approach. A noticeable amount of hysteresis has been observed during indentations. Analysis of the experimental data indicates that stress relaxation in the visco-elastic corneo-scleral shell is the primary factor of the observed hysteresis. Further tests under different indentation rates show that the novel tonometer is expected to have an accuracy of ± 1mmHg when the indentation rate is kept below 0.5 mm/sec for pressure range of 10-35 mmHg. © Springer International Publishing Switzerland 2014.