Abstract
This was a cross-sectional analytic study conducted to compare intraocular pressure
(IOP) measurements by non-contact tonometer (NCT) and a standard Goldmann
applanation tonometer (GAT) in glaucoma and non-glaucoma patients. One hundred and
forty-eight outpatients attending Thamuang Hospital in the period December 2007 - January
2008 were categorized into two groups: the glaucoma group comprised 48 patients
(48 right eyes, 47 left eyes) and the non-glaucoma group comprised 100 patients (99 right
eyes, 100 left eyes). None of the patients had a history of ocular surgery or corneal disease.
Their IOP were measured by two independent parallel observers using non-contact
tonometer Canon TX-F and Goldmann applanation tonometer.
The results of the study disclosed that the intraocular pressures measured by the
non-contact tonometer were significantly different from those measured by the Goldmann
applanation tonometer (paired t-test statistical analysis p < 0.05) in both glaucoma and non-glaucoma groups. Mean IOP in the glaucoma group, measured by NCT, was lower
than GAT (4.63 ±3.14 mmHg right eye, 4.33±3.50 mmHg left eye); also, the mean IOP in
the non-glaucoma group, measured by NCT, was lower than GAT (1.95±2.89 mmHg right
eye, 2.40±2.62 mmHg left eye). The pressure difference increased in cases with a higher
IOP, thus reflecting the reliability of NCT measurement only in measurement of the cases
with normal intraocular pressure range. Therefore, repeat intraocular pressure measurement
should be performed to conform with the standard Goldmann applanation tonometer,
if necessary.
