Comparison of the iCare tonometer with the Goldmann tonometer in Malawi

The risk for glaucoma is 4-5 times higher in patients from sub-Saharan Africa. Thus, especially in developing countries an easy and effective method for assessing the intraocular pressure (IOP) is needed. In this hospital-based survey 150 eyes were divided into 3 groups concerning the IOP (group I < 16 mmHg, group II 16-23 mmHg and group III > 23 mmHg) and underwent examination with ultrasound pachymetry followed by iCare tonometry (ICT) and Goldmann applanation tonometry (GAT). Agreement of the measurements by two tonometers was assessed with the Bland-Altman method and the influence of the central corneal thickness (CCT) on the ICT measurements was determined. The mean difference between the IOD measured with GAT and ICT was 0.84 +/- 2.63 mmHg. The differences were similar in all three groups (0.77-0.97 mmHg), however, the standard deviation in group III (4.04 mmHg) was greater than in groups I (1.98 mmHg) and II (1.79 mmHg). The mean CCT was 513.51 +/- 36.22 A mu m. The agreement of measurements by GAT and ICT was good for lower IOP values but less accurate in patients with higher IOP values (group III). A dependency of the CCT on the ICT measurements was observed. In comparison to other countries the lowest CCTs were found in Malawian patients.