Rebound tonometer: ideal tonometer for measurement of accurate intraocular pressure

To assess the accuracy of a rebound tonometer (RT) in patients with glaucoma, comparing the measurements with those obtained by a noncontact tonometer (NCT) and a Goldmann applanation tonometer (GAT).

A total of 71 patients (142 eyes) with glaucoma from our hospital-based glaucoma clinic were included in the study. Intraocular pressure (IOP) was measured with RT, NCT, and GAT with an interval of 10 minutes, in between the readings obtained by the different tonometers.

In eyes with normal IOP, the IOP measured by RT is 1 to 3 mm Hg higher than that by NCT and 2 to 3 mm Hg higher than that by GAT. There was a trend toward greater difference when the IOP values were higher (>21 mm Hg). Mean IOP readings recorded by RT were higher than IOP recorded by NCT and GAT. A statistically significant tendency to an overestimation of IOP with RT as compared with GAT was found.

IOP readings obtained by an I-care tonometer in our study have shown reasonable concordance with GAT. Overestimation of IOP measured by RT as compared with GAT is directly proportional to the IOP. As the I-care tonometer measured IOP with good accuracy, it may be considered as an appropriate method for clinical use in normal subjects and glaucoma patients.