Abstract
Purpose:
The goals of the study were to analyze the correlation of Goldmann applanation tonometer (GAT), ICare and Tono-Pen tonometers in young healthy persons. To investigate the influence of central corneal thickness (CCT) on intraocular pressure (IOP) measurements recorded with all tonometers assessed in this study.
Methods:
A prospective clinical study conducted on 78 eyes of 78 (n=78) subjects in the age group 22 to 28 years was performed. IOP was measured using GAT, ICare and Tono-Pen tonometers, followed by measurements of CCT. The statistical analysis was performed using SPSS 20.00.
Results:
The study included 44 (56,41%) women and 34 (43,59%) men. The mean age of the participants was 23,8 years. Mean IOP and standard deviation (+/-SD) for GAT, iCare and Tono-Pen tonometers were 15,61mmHg(+/-2,28), 16,29mmHg(+/-2,726) and 16.32mmHg(+/-2,393) respectively. Mean CCT was 555 μm (+/- 29,648). Clear positive correlations between GAT and ICare, GAT and Tono-Pen and Icare and Tono-Pen tonometer were found (r= 0.867, p<0.001; r= 0,861, p<0,001; r=0,915, p<0,001) respectively. Bland-Altman analysis showed a mean difference (MD) of measurements by GAT and ICare of -0,679 mmHg (SD=1,363, p<0,001), by GAT and Tono-Pen of -0,705 (SD=1,239, p<0,001) and by Icare and Tono-Pen of -0,026 (SD=1,104, p>0,05). Comparing GAT to both non-gold standard tonometers they were affected by CCT: both Icare and Tono-Pen tonometer values were statistically significant higher by higher CCT means (>555μm), (MD= -1,282, p<0,001; MD= -0,949, p<0,001), respectively.
Conclusions:
Both ICare and Tono-Pen tonometers overestimated the GAT values. Both ICare and Tono-Pen could be used equally instead of GAT, because they didn’t show any statistically significant difference compared to each other. Higher CCT values (>555μm) overestimate IOP values.