Comparison of IOP obtained in different kind of eyes with contact and no contact tonometers.

BACKGROUND: The aim of this study is to analyze and compare the intraocular pressure (IOP) values measured in three different kinds of participants such as healthy subjects (HS), keratoconus patients (KP), and those who underwent myopic photorefractive keratectomy (MPRK). The devices used in this study are the Goldmann Applanation Tonometry (GAT), the dynamic contour tonometry (DCT), the ocular response analyzer (ORA), and the Corvis ST (CST). SUBJECTS AND METHODS: This research included 92 eyes of 92 h, 63 eyes of 63 KP, and 58 eyes of 58 MPRKM. Each participant underwent a complete ophthalmic evaluation and IOP measurement with GAT, DCT, ORA, and CST. A statistical analysis was conducted to detect possible differences and correlations. RESULTS: First, according to the observed data, HS eyes displayed mean IOP values measured with GAT, DCT, ORA, and CST, respectively, 15.82 ± 2.74 mmHg, 17.63 ± 2.28 mmHg, 16.24 ± 3.14 mmHg, and 17.31 ± 3.21 mmHg. Then, KP eyes showed mean IOP values measured with GAT, DCT, ORA, and CST of, respectively, 14.89 ± 1.64 mmHg, 16.97 ± 2.08 mmHg, 13.09 ± 3.12 mmHg, and 13.78 ± 2.11 mmHg. Finally, MPRK eyes showed mean IOP values measured with GAT, DCT, ORA, and CST of, respectively, 13.92 ± 1.34 mmHg, 15.39 ± 2.86 mmHg, 16.63 ± 2.51 mmHg, and 15.06 ± 1.56 mmHg. CONCLUSION: According to the observed data, ORA and GAT might be used interchangeably in HS, whereas GAT, ORA, and CST in KP eyes. Moreover, it has been noticed that in those eyes that previously undergone a myopic PRK, GAT provided lower values of IOP in comparison with other devices.

Analysis of differences in intraocular pressure evaluation performed with contact and non-contact devices.

BACKGROUND: To evaluate differences of intraocular pressure (IOP) measurements performed with Goldmann applanation tonometer (GAT), dynamic contour tonometer (DCT), rebound tonometry (RT), Ocular Response Analyzer (ORA) and Corvis ST (CST) in eyes screened for refractive surgery. METHODS: One eye, only the right one, of 146 patients was included in this study. Each participant was submitted to a corneal analysis with Scheimpflug camera and IOP evaluation with GAT, DCT, RT, ORA and CST. Differences in IOP values obtained thanks to each instruments were compared and then correlations between these discrepancies and morphological features such as mean keratometry (MK) and central corneal thickness (CCT) provided by Pentacam were studied. Software used to run statistical evaluations was SPSS, version 18.0. RESULTS: Study participants had a mean age of 33.1 ± 9.2 years old. IOP values observed in this study were 15.97 ± 2.47 mmHg (GAT), 17.55 ± 2.42 mmHg (DCT), 17.49 ± 2.08 mmHg (RT), 18.51 ± 2.59 mmHg (ORA) and 18.33 ± 2.31 mmHg (CST). The mean CCT was 560.23 ± 31.00 µm, and the mean MK was 43.33 ± 1.35 D. GAT provided significant lower values in comparison to all other devices. DCT and RT gave significantly lower intermediate IOP values than those measured with ORA and CST. All the IOP measures and the differences between devices were significantly correlated with CCT. CONCLUSIONS: According to our data, although our findings should be confirmed in further studies, GAT tonometer cannot be used interchangeably with DCT, RT, ORA and CST.

Intraocular pressure evaluation in healthy eyes and diseased ones using contact and non contact devices.

PURPOSE: To analyze and compare intraocular pressure (IOP) values measured in healthy subjects (HS), keratoconus (KC) patients and patients that underwent myopic photorefractive keratectomy (REF), using Goldmann applanation tonometry (GAT), dynamic contour tonometry (DCT), ocular response analyzer (ORA) and Corvis ST (CST). METHODS: The study included 76 eyes of 76HS, 15 eyes of 15 KC patients and 18 eyes of 18 subjects that underwent REF. Each participant underwent a complete ophthalmic evaluation, IOP measurement with GAT, DCT, ORA and CST. RESULTS: HS showed a mean GAT value of 15.62±2.33 mm Hg, a mean DCT value of 17.44±2.51 mm Hg, a mean ORA value of 15.99±3.58 mm Hg and a mean CST value of 17.24±3.44 mm Hg. KC showed a mean GAT value of 15.07±1.83 mm Hg, a mean DCT value of 17.01±1.96 mm Hg, a mean ORA value of 13.58±2.99 mm Hg and a mean CST value of 14.37±1.89 mm Hg. REF showed a mean GAT value of 14.06±1.51 mm Hg, a mean DCT value of 15.12±2.34 mm Hg, a mean ORA value of 16.85±2.4 mm Hg and a mean CST value of 15.57±1.77 mm Hg. CONCLUSION: Our data suggest that ORA and GAT could be used interchangeably in HS; GAT, ORA and CST could be used interchangeably in KC patients and that GAT provides lower IOP values compared to the other devices in eyes previously submitted to myopic PRK.

Comparison between Corvis and other tonometers in healthy eyes.

PURPOSE: To determine the agreement of intraocular pressure (IOP) values in healthy eyes among Goldmann applanation tonometer, dynamic contour tonometer, ocular response analyzer and Corvis. Additionally, to study the relationship between their differences with central corneal thickness (CCT) and corneal curvature (CK). METHODS: Seventy-six eyes of 76 healthy subjects were examined. Every subject underwent a complete ophthalmic evaluation, a Pentacam scan and three consecutive IOP measurements with each instrument (DCT, GAT, ORA and CST). IOP measurements provided by each device were compared with each other and the differences between them were correlated with morphological parameters obtained by Pentacam (CCT and CK). Statistical analysis was performed using SPSS software, version 18.0. RESULTS: The mean age of enrolled subjects was 36.8 ± 10.6 years old. The mean IOP measurements that were obtained with GAT, DCT, ORA and CST was 15.62 ± 2.33 mmHg, 17.44 ± 2.51 mmHg, 15.99 ± 3.58 mmHg and 17.24 ± 3.44 mmHg respectively. The mean CCT was 543.63 ± 36.15 µm, the mean CK was 43.35 ± 1.23 D. GAT and ORA provided IOP values not showing a statistical difference; CST and DCT IOP measurements did not show a statistical difference whereas CST provided statistically higher IOP values both than GAT and both ORA. CONCLUSIONS: According to our data, CST produces IOP values that are notably higher than GAT measures; therefore they cannot be used interchangeably. If CST should be used as the next gold standard, higher IOP values will come to be considered normal.