Comparison of the Transpalpebral Tonometer TGDc-01 with Goldmann Applanation Tonometry

Abstract

This study aimed to compare intraocular pressure (IOP) measurements obtained by the transpalpebral tonometer TGDc-01 and by the Goldmann applanation tonometer (GAT). IOP was measured by the conventional GAT and the TGDc-01 tonometer. Central corneal thickness (CCT) was measured for all eyes. Sixty-seven consecutive patients (123 eyes) participated. The mean difference between the 2 techniques (TGDc-01-GAT) was -0.93 mmHg, SD=2.74 (p=0.0002, paired t-test), and 70% of the measurements were within +/-2 mmHg. The correlation coefficient was 0.67 (p<0.0001). A subgroup analysis according to CCT was conducted. For CCT <520 microm, the mean IOP difference was 0.67 mmHg (p=0.13); r=0.75 (p<0.001). For CCT 520 microm-580 microm, the mean IOP difference was -1.08 mmHg (p=0.001); r=0.69 (p<0.0001). For CCT>580 microm, the mean IOP difference was -2.29 mmHg (p=0.0003); r=0.57 (p=0.003). TGDc-01 may estimate IOP with a fair agreement to the Goldmann tonometer, although caution should be used for patients who require precise IOP measurements. TGDc-01 measured higher IOPs than Goldman tonometry for thinner corneas, a trend that was reversed for thicker corneas. This tonometer is a portable device, easy to use, does not require anesthetic drops, and may be suitable for IOP screening.