Intraocular pressure measurements with the newly reconfigured Ocuton S*TT-MV self-tonometer in comparison to Goldmann applanation tonometry in glaucoma patients.

Background: This study compared the new Ocuton S*TT-MV to the Ocuton S (former configuration) and GAT. The effect of the reconfiguration on measuring accuracy and device handling of glaucoma patients was evaluated.
Material/methods: 101 glaucoma patients performed self-measurements using the old Ocuton S and the Ocuton S*TT-MV. The new Ocuton S*TT-MV automatically verifies the applanated area. We used GAT as the gold standard reference. Three series of measurements were performed in random order.
Results: The mean IOP was 18.3+/-4.2 mmHg with Ocuton S, 17.5+/-3.6 mmHg with the reconfigured Ocuton S*TT-MV, and 15.1+/-3.4 mmHg with GAT. IOP ranged from 9 to 30.5 mmHg with GAT, 7 to 42 mmHg with Ocuton S*TT-MV, and 5 to 38 mmHg with the old Ocuton S. The mean difference between the old Ocuton S and GAT was 3.2+/-3.5 mmHg, between Ocuton S*TT-MV and GAT 2.4+/-3.3 mmHg, and between old and new Ocuton S 0.9+/-2.9 mmHg (p<0.01). The standard deviation within an individual row of 4 readings per eye with the old Ocuton S averaged 1.9 mmHg, while with the new Ocuton S*TT-MV the standard deviation averaged 1.7 mmHg. This measuring accuracy showed no age correlation for either self-tonometer (old Ocuton S: coefficient of correlation R=0.2; Ocuton S*TT-MV: coefficient of correlation R=0.053).
Conclusions: The newly reconfigured Ocuton S*TT-MV improves measuring accuracy significantly and approaches the accuracy achieved using GAT. Improved usability of self-tonometers has clinical relevance, as patients don't have to check the corneal cast on the measuring prism. This could lead to an increased usage of self-tonometry in glaucoma monitoring.