Abstract
Purpose: :
The object of this study was to compare intraocular pressure measurements obtained with the Diaton, a new digital transpalpebral indentation tonometer, with those from Goldmann applanation tonometry (GAT) in normal and glaucomatous eyes.
Methods: :
Sixty six eyes of 33 consecutive subjects, 46 eyes having glaucoma and 20 eyes without glaucoma, were included in the study. Patients were excluded with clinically significant lid, scleral or motility disorders, a history of recent intraocular surgery or previous trabeculectomy, glaucoma shunt, or scleral buckle. Goldmann tonometry was perfomed by one of the authors, while the Diaton measurements were performed by another author in a masked fashion. Applanation measurements were performed in a upright sitting position taking two IOP readings. Diaton measurements were performed until the device signaled acceptable measurements, with the back of the chair reclined to achieve a horizontal head position.
Results: :
The age of the glaucoma group subjects ranged from 46 to 90 years (mean 69.37,SD 10.07) and in the normal group ranged from 62 to 88 years (mean 76.85, SD 9.07). The Goldman applanation IOP in the normal group ranged from 11 to 19 mmHg (mean 14.55 and SD, 2.32 ) ,while the Diaton measurement for the same group ranged from 12 to 19 mmHg (mean 14.95 and SD, 2.21). While for the glaucoma group, the Goldman applanation IOP ranged from 6 to 31 mmHg (mean 15.42 and SD, 4.77) , while the Diaton measurement for the same group ranged from 9 to 31 mmHg (mean 16.13 and SD, 4.30). The Pearson's correlation coefficient r between Goldman applanation pressure and Diaton pressure was 0.725 for the whole group (66 eyes, p <0.01) and 0.778 for the glaucoma group with p < 0.01. In both normal and glaucoma groups, 15.15% of the Diaton measurements exactly the same as the Goldman applanation tonometer, Diaton under-estimated the IOP compared to the applanation pressure in 37.87% (1-6 mmHg), and over-estimated the IOP by (1-8 mmHg) in 43.93% of the eyes tested. The difference between Diaton and GAT reading was ≤ 1 mmHg in 51.51% of eyes measured, ≤2 mmHg in 65.15%, < 3 mmHg in 83.33%, ≤4 mmHg in 89.39%, and was 5-8 mmHg in 10.6% of eyes measured.
Keywords: intraocular pressure