ABSTRACT
Objective: The aim of this study was to compare intraocular pressure [IOP] measured with the Tono-Pen[registered] to that measured using the Goldmann applanation tonometer [GAT] in patients with primary open angle glaucoma attending a glaucoma clinic
Subjects and Methods: A comparative clinic- based observational study was conducted involving 75 patients [39 men and 36 women] attending a glaucoma clinic in Southwest Nigeria. A pretested structured questionnaire was used to collect sociodemographic data. The Tono-Pen and the GAT were used to measure the IOP in each patient. Central corneal thickness [CCT] was measured with an ultrasonic pachymeter, and the corrected GAT value was calculated for each patient. The Tono-Pen readings were compared with the uncorrected and corrected GAT readings. Descriptive and comparative analyses were performed. Values for p < 0.05 were considered statistically significant
Results: The mean age of the participants was 60.39 +/- 16.71 years. The mean IOP using the Tono-Pen was 21.1 +/- 6.8 mm Hg versus the mean uncorrected GAT value of 17.1 +/- 6.9 mm Hg and the corrected GAT value of 18.9 +/- 7.5 mm Hg. The mean CCT was 510.5 +/- 29.6 micro m. The mean differences between the Tono-Pen reading and uncorrected and corrected GAT readings were 3.9 +/- 2.6 and 2.1 +/- 3.5 mm Hg, respectively. Gender [Tono-Pen vs. GAT; p = 0.981 vs. 0.437] and corneal thickness [p = 0.057] did not significantly affect the IOP value. Of the 75 patients, 68 [90.7%] preferred the Tono-Pen to the GAT
Conclusion: In this study, the Tono-Pen gave a higher value for IOP than the uncorrected and corrected GAT values. Gender and corneal thickness did not significantly affect the measurements. Most patients found the Tono-Pen more acceptable than the GAT