Diaton tonometry: an assessment of validity and preference against Goldmann tonometry

Abstract

To assess agreement between the Diaton, a new transpalpebral tonometer, and Goldmann applanation tonometry, the accepted gold standard. Comparative study of two devices in a hospital setting. Two hundred and fifty-one patients attending the eye casualty and general ophthalmology clinics at St James' University Hospital, Leeds between February and December 2009. Intraocular pressure was measured using Goldmann applanation tonometry and Diaton tonometry by one examining ophthalmologist. Patient preference for either technique was also recorded. Intraocular pressure measured by Diaton was compared with intraocular pressure measured by Goldmann applanation tonometry. Limits of agreement were determined using the Bland-Altman method. Two hundred and fifty right eyes underwent both Goldmann applanation tonometry and Diaton tonometry. Mean intraocular pressure was 13.8 ± 3.6 mmHg using Goldmann applanation tonometry and 13.2 ± 4.3 mmHg using Diaton tonometry. Upper and lower limits of agreement were +8.4 mmHg and -9.6 mmHg, respectively. Order of intraocular pressure measurement and positioning did not influence limits of agreement in a clinically significant manner. Overall, more patients expressed preference for Diaton tonometry (40.2%) than Goldmann applanation tonometry (30.3%). Those aged 50 or less were more likely to prefer Diaton tonometry. The Diaton tonometer is portable, lightweight, user-friendly and well tolerated by patients. However, it shows poor agreement with Goldmann applanation tonometry, thereby precluding it from being regarded as a substitute in routine clinical practice.