Evaluation Of A New Eyelid Self-Tonometer, Tapeye: Comparison With Goldmann Applanation Tonometer

Lowering the intraocular pressure (IOP) is considered the only treatment for glaucoma, and eye drops are used, but intraocular pressure fluctuates throughout the day, making it difficult to apply eye drops at appropriate times. Self-tonometry is a valuable option for recording out of the- office IOP because the IOP fluctuates both within and across days. We are developing a home-use self-monitoring tonometer, TapEye, which can be approached from above the eyelid. The purpose of the present study was to investigate the feasibility and accuracy of TapEye self-tonometer measurements in comparison with those from a Goldmann applanation tonometer (GAT), and to examine the association between the obtained IOP values.

Yokohama Tsurumi Chuo Eye Clinic

This study (jRCTs032220268) was approved by the Certified Review Board of Hattori Clinic, and followed the tenets of the Declaration of Helsinki. Selection criteria were: aged 18 years or older, normal subjects and patients with confirmed or suspected glaucoma, no history of ocular trauma. The study subjects used the research instruments TapEye tonometer and the control instruments GAT and non-contact tonometer (NCT). Tap Eye is a tonometer measuring by pressing the eyelid skin and its value of IOP is displayed on original software under seven consecutive measurements. To assess the change over time in IOP, the subjects repeated the measurements at baseline and one month.

A total of 104 subjects were recruited and their both eyes were examined during 1-month. The mean IOP was 14.4 ± 2.2, 15.6 ± 2.4, and 15.9 ± 2.3 mmHg in TapEye, GAT, and NCT, respectively. The mean difference between TapEye and GAT was -1.2 ± 3.2 mmHg (p<0.001, paired t test) and between NCT and GAT measurements it was 0.2 ± 2.3 mmHg (p=0.03, paired t test). Since no significant correlation was found between TapEye and GAT in IOP (r=0.04, p=0.37), there was significant correlation between NCT and GAT (r=0.48, p<0.001). The mean difference between baseline and 1-month was -0.3 ± 3.1, 0.1 ± 2.1, and 0.6 ± 2.0 mmHg in TapEye, GAT, and NCT, respectively.

TapEye can be used as a self-tonometer; however, the correlation with GAT was not appropriate for IOP measurements in terms of accuracy. It is suggested that TapEye might track individual changes in IOP over time.