Measurement of the Intraocular Pressure with the "Eyelid tonometer" - TGDc-01 in Comparison to Applanation and Pneumotonometry

Abstract

Abstract: : Purpose: An irregular corneal surface compromises IOP measurements by Goldmann applanation tonometry. For these patients an accurate measurement without corneal contact would be desirable. The new eyelid tonometer TGDc-01 measures IOP without corneal contact through the eyelid. The aim of the study was to evaluate the accuracy of the eyelid tonometer compared to Goldmann applanation tonometry and pneumotonometry by OBF in subjects without corneal alterations. Methods: IOP was measured in 250 eyes of 125 subjects without corneal alterations with three different methods. Measurements with the eyelid tonometer TGDc-01 and the Goldmann applanation tonometer were performed within 5 minutes in a random order. OBF tonometry was performed within 30 minutes before or after. Results: The mean difference between lid tonometry and Goldmann applantion tonometry was 0.46 mmHg, SD +/-2.78 mmHg. The correlation between both methods was statistically significant (r = 0.856; p < 0.01). In the reliability analysis the intraclass correlation coefficient was 0.8511. Compared to Goldmann applanation tonometry 78% of the IOP readings measured by lidtonometry were in an interval of +/- 2 mmHg, 88% in an interval of +/-3 mmHg with a maximum deviation of -11 / +15 mmHg. The mean difference between lidtonometry and pneumotonometry by OBF was 1.43 mmHg SD +/ 4.43 mmHg. The correlation between these methods was r = 0.611; p < 0.01, the intraclass correlation coefficient was 0.6583. Compared to pneumotonometry 51.6% of the IOP readings measured by lidtonometry were in an interval of +/- 2 mmHg, 65.9% in an interval of +/- 3 mmHg and 84.2% in +/- 5 mmHg with a maximum deviation of -18/+19 mmHg. Conclusions: Lidtonometry correlates well with Goldmann applantion tonometry, but in more than 10% of the measurements the IOP readings differed more than 3 mmHg. The eyelid tonometer might be helpful when Goldmann applanation tonometry is not applicable.

Keywords: intraocular pressure • eyelid • clinical (human) or epidemiologic studies: sys