Icare Pro Rebound Tonometer Research Articles

Rebound tonometry measurements over extended-wear bandage contact lenses

BackgroundThe aim of this study was to assess the validity of rebound tonometry measurements obtained over eyes wearing extended-wear bandage contact lenses with the highest oxygen transmissibility (Dk/t) value of 175 @ -3.00 D. MethodsA total of 151 normal eyes were included in this prospective pretest-posttest study. A rebound tonometer (iCare PRO) was used to collect intraocular pressure readings from “naked” eyes (eyes without contact lenses) and the same eyes wearing extended-wear lotrafilcon A bandage contact lenses (Alcon Air Optix Night & Day Aqua Contact Lenses). The mean pre- and post-application values were pooled and compared using the paired t-test. ResultsThe application of extended-wear lotrafilcon A contact lenses over normal eyes did not cause a statistically significant change in the intraocular pressure measurements obtained using an iCare PRO tonometer (13.74 ± 2.15 mm Hg vs. 13.77 ± 2.26 mm Hg, p-value = 0.6506). ConclusionBased on this study conducted on normal eyes, the removal of extended-wear bandage contact lenses is not necessary when taking intraocular pressure measurements using the iCare PRO rebound tonometer.

The influence of corneal geometrical and biomechanical properties on tonometry readings in keratoconic eyes.

To identify the effect of corneal geometrical and biomechanical parameters on the intraocular pressure (IOP) measurements obtained by Goldmann Applanation Tonometer (GAT), non-contact tonometer, iCare Pro Rebound Tonometer (IRT), Tonopen and Ocular Response Analyzer (ORA, Goldmann-correlated IOP: IOPg, corneal compensated IOP: IOPcc). We prospectively recruited patients with a tomographically confirmed diagnosis of keratoconus. IOP measurements were performed in the following order: non-contact tonometry, ORA, IRT, GAT and Tonopen. The means of the three IOP measurements were used for the analysis. Correlation analyses were performed to assess the association between tonometer readings and the corneal geometrical and biomechanical parameters including ORA waveform parameters. Tonometer variability was assessed using a stepwise linear regression analysis. Fifty-one patients with keratoconus (27 females, mean age 30.8 ± 8.7years) were evaluated. The highest mean IOP was measured by IOPcc (14.6 ± 2.3mmHg) followed by IRT IOP (13.0 ± 3.2mmHg), Tonopen IOP 12.0 ± 2.6mmHg), GAT IOP (11.7 ± 3.1mmHg), NCT IOP (10.2 ± 3.2mmHg) and IOPg (10.2 ± 3.6mmHg). NCT and IOPg were affected from all corneal parameters including thickness, curvature and biomechanical parameters. While GAT and IRT had significant correlations with corneal resistance factor (CRF) and corneal hysteresis, IOPcc only had a significant correlation with CRF. None of the corneal factors had any statistically significant correlation with Tonopen. CRF predicted tonometer measurement variability in 7 of the 15 inter-device variability assessments. Tonopen was the least affected from the corneal parameters followed by IOPcc and GAT. CRF was a strong determinant of tonometer variability.

Comparability of three intraocular pressure measurement: iCare pro rebound, non-contact and Goldmann applanation tonometry in different IOP group

BackgroundMeasurement of intraocular pressure (IOP) is essential for glaucoma patients. Many factors such as central corneal thickness (CCT) can affect the accuracy of IOP measurement. The purpose of this study was to evaluate the agreement of IOP measured by non-contact tonometer (NCT), iCare pro rebound tonometer (iCare), and Goldmann applanation tonometer (GAT) in different IOP group.MethodsThis was a Hospital-based cross-sectional study. Two hundred subjects were enrolled in this study. All subjects underwent IOP measurement using an NCT–iCare–GAT sequence. Bland-Altman, Pearson correlation and intraclass correlation analysis were performed using SPSS 17.0 software. The influence of CCT on each IOP measurement methods was evaluated by linear regression analysis.ResultsThe mean difference (Δ) of NCT–GAT did not differ from (Δ) iCare–GAT in IOP < 10 and 10–21 mmHg group. However, (Δ) NCT–GAT was significantly higher than (Δ) iCare–GAT in IOP 22–30 and > 30 mmHg group (P < 0.05). Bland–Altman analysis showed significant agreement between the three devices (P < 0.01). IOP measurements of the three methods were significantly correlated with CCT (P < 0.01).ConclusionsICare pro shows a higher agreement with GAT over a wide range of IOP compared with NCT. The consistency between the three tonometers was similar in a low and normal IOP range. However, NCT shows a greater overestimate of IOP in moderate and higher IOP group. The variability of IOP measurement affected by CCT is NCT > iCare pro > GAT.

Tonometry after Intrastromal Corneal Ring Segments for Keratoconus.

Reliable intraocular pressure (IOP) measurement after intrastromal corneal ring segments (ICRS) implantation is a challenge because of altered corneal morphology. In this study, IOP is measured with four tonometers, compared with Goldmann applanation tonometry (GAT) values and the influence of corneal parameters is established. This study compares IOP measurements made using different tonometers in patients implanted with ICRS and assesses the effects of central corneal thickness (CCT), corneal curvature, and corneal astigmatism on the IOP measurements obtained. In this cross-sectional study, IOP was measured using three different tonometers in 91 eyes of 91 patients with corneal ectasia implanted at least 6 months previously with ICRS. The tonometers tested were the TonoPen XL, Pascal dynamic contour tonometer (DCT), and iCare Pro rebound tonometer. GAT measurements were used as reference. Agreement among the IOPs provided by the different tonometers and the influence of corneal variables on the IOP measurements obtained were assessed using the Bland-Altman method, intraclass correlation coefficients, and multiple linear regression analysis. Mean IOP differences were GAT versus TonoPen XL -0.8 ± 3.07 mm Hg, GAT versus DCT -1.0 ± 3.26 mm Hg, and GAT versus iCare Pro 0.8 ± 2.92 mm Hg. Our multiple linear regression analysis identified CCT as a confounding factor affecting all the tonometer readings but DCT-IOP. In patients fitted with ICRS, IOP measurements made using the iCare Pro and TonoPen XL showed most agreement with GAT. Intraocular pressure measurements made by DCT were unaffected by corneal topographic factors though this procedure slightly overestimated GAT readings.

Time Course of Conjunctival Hyperemia Induced by a Rho-kinase Inhibitor Anti-glaucoma Eye Drop: Ripasudil 0.4%

ABSTRACTPurpose: We investigated the detailed time course of conjunctival hyperemia induced by ripasudil 0.4%, a novel Rho-kinase inhibitor anti-glaucoma eye drop, in healthy subjects.Methods: We recruited 51 healthy subjects and administered ripasudil 0.4% in their right eye. We evaluated conjunctival hyperemia using slit lamp photography and measured the intraocular pressure (IOP) using the Icare PRO Rebound Tonometer at baseline and after 5, 15, 30, 60, 90, and 120 min. The conjunctival hyperemia score was graded by three independent observers on a scale of 0 (none) to 3 (severe). Additionally, we analyzed the “percent coverage” of conjunctival hyperemia by using an automated hyperemia analysis software program; this program provides the pixel coverage of the conjunctival vessels in the region of interest. Dunnett and Steel multiple comparison tests were used, as appropriate, for the subsequent analyses.Results: The conjunctival hyperemia score and percent coverage increased rapidly after the instillation of ripasudil 0.4%, peaking at 15 min (score: 1.83 ± 0.29 [mean ± SD]) and 5 min (11.6% ± 4.7%), respectively, and then gradually decreasing until 120 min (0.45 ± 0.22 and 4.7% ± 1.8%, respectively), when they reached a level that was not significantly different from the baseline values. The IOP decreased significantly compared to the baseline at 30, 60, and 90 min, based on the Dunnett test.Conclusion: Conjunctival hyperemia induced by ripasudil 0.4% peaks rapidly to moderate severity, but subsides relatively quickly.

Comparability of Icare Pro Rebound Tonometer with Goldmann Applanation and Noncontact Tonometer in a Wide Range of Intraocular Pressure and Central Corneal Thickness

Purpose: To evaluate the agreement between the reading values of the Goldmann applanation tonometer (GAT), Icare Pro rebound tonometer (IRT) and noncontact tonometer (NCT) in glaucoma patients. Methods: This cross-sectional study comprised 292 eyes of 292 patients selected from a glaucoma outpatient clinic. The intraocular pressure (IOP) was measured sequentially, at a 10-min interval each, in the following order: NCT, IRT and GAT. The central corneal thickness (CCT) was measured using Pentacam HR before the IOP measurements. Results: The mean IOPs measured by the GAT, NCT and IRT were 20.17 ± 6.73 mm Hg (range: 4-48), 19.77 ± 6.88 mm Hg (range: 3-46) and 19.30 ± 5.15 mm Hg (range: 7.30-44.5), respectively. The correlation coefficients of the GAT and IRT, NCT and IRT, and GAT and NCT measurements were r² = 0.673, r² = 0.663 and r² = 0.938 (all p < 0.001), respectively. The IRT tends to overestimate in the low GAT-measured IOPs, whereas it underestimates in high GAT-measured IOPs. The measurements of all 3 devices were also correlated with the CCT at a statistically significant level (GAT: r² = 0.063, NCT: r² = 0.063, IRT: r² = 0.058). Conclusion: The agreement between the IRT and GAT measurements is higher in the IOP range of 9-22 mm Hg, whereas significant discrepancies occur as the IOP deviates from normal values. The variability of the IRT and GAT measurements over a wide range of CCT is minimal.

Reliability Comparison of Rebound Tonometer at the Upright and Supine Position

Purpose: Rebound tonometer has been used to measure the intraocular pressure (IOP) in the supine as well as normal upright positions. We investigated the reliability of IOP measurements using the rebound tonometer in the upright and supine positions. Methods: IOP was measured in 30 patients (60 eyes) with open-angle glaucoma who had no history of ocular surgery and no anterior segment pathology, in both the upright and supine positions using rebound tonometer (IcarePRO; Icare Finland Oy, Finland). The average IOP value after 6 measurements was recorded. We measured IOP repeatedly until 3 reliable values within normal limits of the measurement’s variation were obtained. We calculated the intraclass correlation coefficient (ICC), coefficient of variation, and number of repeated measurements necessary to obtain 3 reliable IOP values in each position as measured by one examiner. Results: ICC values for IOP measurements were 0.852 (95% confidence interval [CI], 0.784-0.903; p < 0.001) in the upright position and 0.684 (95% CI, 0.563-0.784; p < 0.027) in the supine position. Coefficient of variation was 8.7 ± 0.1% in the upright position and 24.0 ± 0.1% in the supine position. An average of 3.3 times of repeated measurements in the upright position and 6.2 times in the supine position were necessary to obtain 3 reliable IOP values within the normal range of standard deviation. Conclusions: When measuring IOP using the IcarePRO rebound tonometer, the measurement reliability was different between the upright and supine positions. Reproducibility of IOP measurements was lower in the upright than the supine position. J Korean Ophthalmol Soc 2015;56(1):93-98

A Comparison of the Icare Pro Rebound Tonometer with Applanation Tonometry in Healthy Infants

Aims: To study the accuracy and patient tolerability of the new Icare Pro rebound tonometer (ICPRO) compared with applanation tonometry in infants aged under 24 months. Methods: Prospective observational study of 50 consecutive patients with expected normal intraocular pressure (IOP). One eye of each patient was examined sequentially using an ICPRO and Perkins applanation tonometer (PAT) to obtain a single adequate IOP measurement for each device. Agreement was assessed using Bland-Altman analysis. An objective assessment of patient tolerance of IOP measurement was also recorded. Results: Mean age of patients was 12.6 months. Correlation of IOP measurement between PAT and ICPRO was moderate (r=0.384, p=0.0059). ICPRO underestimated IOP in 88% of cases: IOP was measured significantly lower with ICPRO (9.18±1.57 mmHg) compared to PAT (12.4±2.95 mmHg, p<0.001). The 95% limit of agreement (LOA) was -8.6 to 2.2 mmHg. Subgroup analysis showed ICPRO underestimated IOP most in infants over 12 months (mean: 4.8mmHg, 95% LOA:-9.5 to 0.2mmHg, p<0.0001). Measurement of IOP with the ICPRO was significantly better tolerated, causing distress and crying in 6%, compared to 62% with PAT (p<0.0001). IOP underestimation with ICPRO was significantly greater when infants were crying during PAT measurement (5.26±2.83) compared to when infants were not crying during PAT measurement (1.97±1.83, p<0.0001). Conclusions: ICPRO appears to be safe, tolerable and of adequate accuracy for the screening of IOP in infants. It consistently significantly underestimated IOP, therefore high or borderline IOPs measured with the ICPRO should be repeated with applanation tonometry to prevent missing cases of raised IOP.

Comparison of Intraocular Pressure Measurements between Icare Pro Rebound Tonometer and Tono-Pen XL Tonometer in Supine and Lateral Decubitus Body Positions

Purpose: To compare intraocular pressure (IOP) measurements obtained using the Icare Pro rebound tonometer and Tono-Pen XL tonometer in supine and lateral decubitus body positions. Methods: One-hundred eyes of 50 subjects (normal volunteers or glaucoma suspects) were enrolled in this prospective observational study. IOP was measured in both eyes using the Icare Pro and Tono-Pen XL in the sitting position and the recumbent positions including supine, right lateral decubitus and left lateral decubitus. IOP was measured five minutes after assuming each of the recumbent postures in a randomized sequence. The eye on the lower side in the lateral decubitus position was termed as the dependent eye. Agreement of IOP readings between the Icare Pro and Tono-Pen was assessed in all recumbent positions. Differences of IOP readings (ΔIOP) between the two tonometers and their correlations with ocular parameters were also assessed in all positions. Results: The IOP readings obtained using Icare Pro and Tono-Pen showed good correlations in supine and lateral decubitus positions (all r > 0.7, p < 0.005), although Icare Pro readings were higher than Tono-Pen readings (all p < 0.001) in all positions. The ΔIOP showed a weakly positive correlation with central corneal thickness in both eyes, whereas such a positive correlation was found only in the dependent eye in the lateral decubitus positions (r = 0.307–0.531, all p < 0.005). Both the spherical equivalents and axial lengths were not correlated with ΔIOP in all positions. Conclusion: IOP readings obtained with Tono-Pen and Icare Pro tonometers showed good agreement in supine as well as in lateral decubitus positions, although Icare readings were higher than Tono-Pen readings in all positions. Such differences in IOP readings between the different tonometers need to be considered when measuring IOPs in various body positions.

Comparison between Goldmann, Icare Pro and Corvis ST tonometry

PurposeTo compare intraocular pressure (IOP) between the new non-contact tonometer Corvis ST (CST), the Goldmann applanation tonometry (GAT) and Icare Pro rebound tonometer (PRO). MethodsA total of 178 eyes of 178 healthy subjects were selected for the study. Measurements of IOP were made in a random order with GAT, PRO and CST. Central corneal thickness (CCT) was determined by ultrasound pachymetry. The mean of three valid measurements of each variable was used in the statistical analysis. The relationship between the tonometers was established using Bland–Altman plots. ResultsMean IOP was 15.5±2.8mmHg for GAT, 15.4±2.8mmHg for CST, and 14.6±2.3mmHg for PRO. The mean differences between pairs of tonometers were: GAT-PRO=0.9±1.7mmHg (p<.001), GAT-CST: 0.1±2.2 (p=.398), and PRO-CST: −0.8±−0.7mmHg, p<0.001. A positive relationship was detected between CCT and the three tonometers: GAT: r=0.325, p<.001; PRO: r=0.385, p<.001, and CST: r=0.428; p<.001. ConclusionsThe differences found between PRO and GAT were significantly higher than those found between CST and GAT, which showed non-significant differences. The measurements of the three tonometers were affected by the CCT.

Concordancia entre la tonometría de Goldmann, Icare Pro y Corvis ST

PurposeTo compare intraocular pressure (IOP) between the new non-contact tonometer Corvis ST (CST), the Goldmann applanation tonometry (GAT) and Icare Pro rebound tonometer (PRO). MethodsA total of 178 eyes of 178 healthy subjects were selected for the study. Measurements of IOP were made in a random order with GAT, PRO and CST. Central corneal thickness (CCT) was determined by ultrasound pachymetry. The mean of three valid measurements of each variable was used in the statistical analysis. The relationship between the tonometers was established using Bland-Altman plots. ResultsMean IOP was 15.5±2.8mmHg for GAT, 15.4±2.8mmHg for CST, and 14.6±2.3mmHg for PRO. The mean differences between pairs of tonometers were: GAT-PRO=0.9±1.7mmHg (P<.001), GAT-CST: 0.1±2.2 (P=.398), and PRO-CST: −0.8±−0.7mmHg, p<0.001. A positive relationship was detected between CCT and the three tonometers: GAT: r=0.325, P<.001; PRO: r = 0.385, P<.001, and CST: r = 0.428; P<.001. ConclusionsThe differences found between PRO and GAT were significantly higher than those found between CST and GAT, which showed non-significant differences. The measurements of the three tonometers were affected by the CCT.

Comparison of Three Intraocular Pressure Measurement Methods Including Biomechanical Properties of the Cornea

The aim of this study was to show the usefulness of three methods for measuring IOP: Goldmann applanation tonometry, rebound tonometry, and Ultra-High-Speed Scheimpflug technology. The examined group consisted of 96 patients (192 eyes), including 63 women and 33 men with a mean age of 59.3 ± 19.9 years. Together, 152 healthy eyes and 40 eyes with different pathologies were examined. Intraocular pressure was measured using the Goldmann applanation tonometer (GAT), the Icare Pro rebound tonometer (RT), and Ultra-High-Speed Scheimpflug technology (UHS ST; Corvis ST with pachymetry). Additionally, corneal pachymetry was conducted with a Scheimpflug camera (Pentacam) and an Ultrasound Pachymeter (A-scan Plus) as a comparison for Corvis ST pachymetry. The mean IOPs were 15.6 ± 3.75 mm Hg, 15.6 ± 3.5 mm Hg, and 16.1 ± 4.0 mm Hg when measured with the GAT, the RT, and the UHS ST, respectively. The mean central corneal thickness (CCT) was 543.7 ± 52.7 μm, 547.9 ± 54.0 μm, and 556.25 ± 38.8 μm as measured with the UHS ST, the Pentacam, and the Ultrasound Pachymeter, respectively. In comparison between devices, there was a significant difference between IOP values measured with the GAT and the RT versus the UHS ST (P < 0.001), and there was no significant difference between GAT and RT (P = 0.5). No significant differences were observed in CCT measured with the UHS ST, Pentacam, and Ultrasound Pachymeter. We showed that the RT Icare Pro ensures IOP measurements that are more comparable with the measurements obtained with the GAT than the measurements that are provided by UHS ST.