PASCAL动态轮廓眼压计与Goldmann压平眼压计在非青光眼人群中眼压测量值的比较及一致性分析

目的探讨在不同的中央角膜厚度(CCT)下PASCAL动态轮廓眼压计(DCT)与Goldmann压平眼压计(GAT)眼压(IOP)测量值的相关性,评价两者测量值的一致性及临床上两种眼压计测量值相互替换的可能性。方法非青光眼病例87例(168只眼)分别用DCT和GAT进行眼压测量,两种仪器的测量顺序随机。同时,用NIDEK UP-1000型角膜测厚仪测量CCT。DCT与GAT眼压测量值的相关性采用Spearson双变量相关分析,Bland-Altman分析法评价两种仪器IOP测量值的一致性。结果 (1)在不同的角膜厚度下DCT与GAT测得的IOP值均显著相关(CCT≤520μm,n=24,r=0.67,P<0.001;520μm580μm,n=44,r=0.61,P<0.001)。(2)DCT眼压测量值与CCT不相关(r=0.14,P=0.08),GAT眼压测量值与CCT显著相关(r=0.59,P<0.001)。(3)Bland-Altman一致性分析显示两种仪器的差值的均值为-0.9mm Hg,一致性界限为(-5.6 mm Hg,3.9 mm Hg)。结论 (1)在不同的角膜厚度下DCT与GAT的眼压测量值均显著相关。(2)DCT眼压测量值与CCT值不相关,GAT眼压测量值与CCT值显著相关。(3)一致性分析显示两者测量值的一致性界限跨度较宽,二者的IOP值不可简单地相互代替。     

Comparison of dynamic contour tonometry and goldmann applanation tonometry in deep lamellar and penetrating keratoplasties

PURPOSE: To compare the measurements of intraocular pressure (IOP) with dynamic contour tonometry (DCT) and Goldmann applanation tonometry (GAT) in eyes with corneal graft and to evaluate the influence of corneal thickness (CCT), corneal curvature (CC), and astigmatism on these methods. DESIGN: Prospective, observational cross-sectional study. METHODS: Eighteen eyes of 18 patients after penetrating keratoplasty (PKP) and 14 eyes of 14 patients after deep lamellar keratoplasty (DLKP) underwent IOP evaluation with DCT and GAT, and measurements of CCT, CC, and astigmatism. Bland-Altman plots were used to evaluate the agreement between tonometers. Multivariate regression analysis was used to evaluate the influence of ocular structural factors and running suture on IOP measurements obtained with both tonometers. RESULTS: IOP values obtained by DCT and GAT were strongly correlated in all eyes (r = .91; P < .001). DCT values measured 2.5 +/- 1.7 mm Hg higher than GAT readings (P < .001). A reduction of the mean IOP difference between DCT and GAT with an increase in IOP values (P < .001) was found. Regression analysis showed no effect of CCT, CC, astigmatism, and running suture on both DCT and GAT readings, either in DLKP or in PKP eyes. CONCLUSIONS: We found a good overall correlation between both tonometers but the agreement between instruments differs in high or low IOP ranges. The wide and varying 95% limits of agreement between DCT and GAT indicates that DCT provides IOP measurements on deep lamellar and penetrating keratoplasties which can be used in the clinical practice.     

Comparison of dynamic contour tonometry with Goldmann applanation tonometry in glaucoma practice

Purpose: To compare intraocular pressure (IOP) readings taken using dynamic contour tonometry (DCT) with IOP readings taken with Goldmann applanation tonometry (GAT) in eyes with glaucoma or ocular hypertension. Methods: The present study included 100 eyes in 100 patients with glaucoma or ocular hypertension. After pachymetry DCT and GAT were performed. Intraocular pressures as measured with DCT and GAT were compared with one another and with central corneal thickness (CCT). Results: Mean DCT IOP measurements (20.1 ± 4.3 mmHg) were significantly (p < 0.001) higher than GAT IOP values (17.9 ± 4.7 mmHg). The mean difference between DCT and GAT measurements was 2.1 mmHg (range ? 3.4 to 9.7 mmHg). The difference followed a normal distribution. Measurements made with DCT and GAT correlated significantly with one another (Spearman’s rho = 0.761, p < 0.001). Neither GAT nor DCT measurements showed a significant correlation with CCT (537 ± 39 μm, range 458–656 μm). Multivariate regression analysis has shown that the difference between DCT and GAT is influenced significantly by ocular pulse amplitude (r = ? 0.334, p = 0.001) and it is not influenced by CCT (r = ? 0.106, p = 0.292). Conclusions: In eyes with glaucoma or ocular hypertension, DCT facilitates suitable and reliable IOP measurements which are in good concordance with GAT readings. Variation in CCT cannot by itself explain the differences in measurements taken with DCT and GAT in a number of eyes.     

Dynamic contour tonometry versus Goldmann applanation tonometry: a comparative study

Background Various sources of error, including central corneal thickness (CCT) and structural corneal rigidity, have been proposed for Goldmann applanation tonometry (GAT). The Pascal dynamic contour tonometer (DCT) is a novel device designed for intraocular pressure (IOP) measurements assumed to be largely independent of CCT and corneal curvature. We compared DCT with GAT in eyes with normal corneas of various thickness.Methods We prospectively measured IOP using DCT and GAT in random order in 100 eyes of 100 subjects (M:F=46:54; mean age 42±19, range 23–88 years).Results Mean DCT values were about 1mmHg higher than GAT readings (16±3 vs 15±3 mmHg, p=0.001). Bland–Altman analysis of individual pairs of DCT and GAT measurements revealed a bias of –1.0 mmHg [95% confidence interval (CI): ±1.2]. Neither GAT nor DCT showed a significant correlation with CCT (533±48, range 399–641 m).Conclusions In eyes with normal corneas, DCT allows suitable and reliable IOP measurements which are in good concordance with GAT. Comparison of DCT with intracameral manometry is desirable in the future.     

Comparison of dynamic contour tonometry with goldmann applanation tonometry

PURPOSE: The dynamic contour tonometer (DCT; Pascal tonometer) is a novel tonometer designed to measure intraocular pressure (IOP) independent of corneal properties. The purpose of this study was a comparison of the DCT with the Goldmann applanation tonometer (GAT) with respect to mean of IOP readings, the influence of ocular structural factors on IOP readings, and both intra- and interobserver variability, in a large group of healthy subjects. METHODS: In a prospective study of 228 eyes, IOP measurements by GAT and DCT were compared, and the effects of central corneal thickness (CCT), corneal curvature, axial length, and anterior chamber depth were analyzed. To evaluate intra- and interobserver variability, IOP was measured in eight eyes by four observers. RESULTS: There was a high concordance between the IOP readings obtained by DCT and GAT. However, IOP readings were consistently higher with DCT than with GAT (median difference: +1.7 mm Hg, interquartile range [25th-75th percentile] = 0.8-2.7 mm Hg). In contrast to GAT, multivariable regression analysis showed no significant effect of corneal thickness, corneal curvature, astigmatism, anterior chamber depth, and axial length on DCT readings. For repeated measurements the intraobserver variability was 0.65 mm Hg for the DCT and 1.1 mm Hg for the GAT (P = 0.008). Interobserver variability was 0.44 mm Hg for the DCT and 1.28 mm Hg for the GAT (P = 0.017). CONCLUSIONS: IOP measurements by DCT are highly concordant with IOP readings obtained from GAT but do not vary in CCT and have a lower intra- and interobserver variability. DCT seems to be an appropriate method of tonometry for routine clinical use.     

DCT和GAT对LASIK手术前后眼压的比较性研究

目的 评价动态轮廓眼压计(DCT)和Goldmann压平眼压计(GAT)对在准分子激光原位角膜磨镶术(LASIK)手术前后眼压测量值的变化.方法 取71例141只眼近视患者在LASIK术前和术后一周分别进行角膜厚度(CCT)、GAT、DCT测量.结果 ①LASIK手术前后DCT测得值尤显著性差异(P=0.062),GAT测得值有显著性差异(P＜0.001),CCT测得值有显著性差异(P＜0001).②Bland-Altman分析示LASIK手术前后DCT与GAT两种测量方法均呈现高度一致性.术前DCT测量值高于GAT测量值1.1mmHg,95%可信区间为(-0.6,2.8)mmHg;术后DCT测量值高于GAT测量值8.2mmHg,95%可信区间为(5.3,11.1)mmhg.③△GAT与△CCT呈正相关,△DCT与△CCT无统计相关性.结论 DCT测量值不受LASIK手术切削的影响,更适合于LASIK手术前后眼压的测量.     

Effect of corneal thickness on intraocular pressure measurements with the Pascal dynamic contour,Canon TX‐10 non‐contact and Goldmann applanation tonometers in healthy subjects

Purpose: To investigate the effects of central corneal thickness (CCT) on intraocular pressure (IOP) measurements of the Pascal dynamic contour tonometry (DCT), Canon TX‐10 non‐contact tonometry (NCT) and Goldmann applanation tonometry measurements (GAT) in healthy subjects. Methods: IOP values of 135 eyes with normal corneas of 135 healthy volunteers were determined by DCT, NCT and by GAT. The CCT was measured using an ultrasonic pachymeter after all IOP determinations had been made. Results: When DCT measurements were compared (IOP = 17.52 ± 2.0 mmHg) with NCT measurements (IOP = 16.54 ± 2.77 mmHg) and GAT measurements (IOP = 15.07 ± 2.35 mmHg), DCT measurements were significantly higher than NCT and GAT (p < 0.001). There was a significant correlation between CCT with both NCT (r = 0.260, p = 0.003) and GAT measurements (r = 0.257, p = 0.005). There was a weak correlation that was not statistically significant between CCT and DCT (r = 0.160, p = 0.079). Conclusion: The IOP measurements with DCT seem to be less dependent on CCT. NCT appears to be more affected by variation in CCT than GAT.     

The effect of corneal edema on dynamic contour and goldmann tonometry

PURPOSE: To determine the effect of contact lens-induced corneal edema on measurements of intraocular pressure (IOP) using the Pascal dynamic contour tonometer (DCT), compared with the Goldmann tonometer. METHODS: Thirty young healthy subjects (23.0 +/- 3.0 years) were recruited from the student population at the University of New South Wales. Thick hydroxyethyl methacrylate contact lenses were worn monocularly for 2 hours under closed-eye conditions to induce corneal edema via hypoxia. IOP (Goldmann and Pascal DCT), ocular pulse amplitude (OPA), and central corneal thickness (CCT) were measured in both eyes before and after lens wear. Paired t-tests, Pearson correlation, and Bland-Altman plots were used to identify changes in, and relationships between, these parameters resulting from corneal edema. RESULTS: Lens wear resulted in statistically significant changes in CCT (+48.3 +/- 14.4 microm, p < 0.001), Goldmann IOP (+1.5 +/- 2.8 mm Hg, p = 0.007), and Pascal DCT IOP (-0.7 +/- 1.1 mm Hg, p = 0.001) but not OPA (0.0 +/- 0.3 mm Hg, p = 0.721, two-tailed paired t-test). The Pascal DCT provided IOP readings that were 1.3 +/- 2.0 mm Hg higher than the Goldmann IOP readings when hydration was normal, but the Goldmann tonometer provided readings that were 0.8 +/- 2.5 mm Hg higher than the Pascal DCT readings when the cornea was edematous. The variation between the two instruments was weakly correlated to the change in CCT (r = -0.261, p = 0.044). CONCLUSIONS: Contact lens-induced corneal edema caused a small underestimation error in IOP measurements by the Pascal DCT, and an overestimation error in Goldmann tonometry measurements. The OPA measurement provided by the Pascal DCT is insensitive to corneal edema-induced changes in corneal properties.     

Is the PASCAL-Tonometer suitable for measuring intraocular pressure in clinical routine? Long- and short-term reproducibility of dynamic contour tonometry

PURPOSE: Dynamic contour tonometry (DCT) is a new technique to measure intraocular pressure (IOP). In several studies no correlation between IOP values and corneal thickness was shown with DCT. This is in contrast to the gold standard, Goldmann applanation tonometry (GAT). The authors evaluated the reproducibility (RP) of DCT compared to GAT, a prerequisite for its introduction into clinical routine. METHODS: IOP was measured with both DCT and GAT in 50 subjects with normal cornea. To evaluate the short-term RP, four DCT and four GAT measurements were performed at day 1 in a randomized order. Long-term RP was determined by one additional measurement per method at day 2, 5, and 8. RESULTS: The short-term RP was defined as the mean value of all standard deviations (SD) of the individual measurements at day 1. Short-term RP was 1.1 mmHg for GAT and 1.2 mmHg for DCT. For long-term reproducibility, mean SD was 1.2 mmHg for GAT and 1.5 mmHg for DCT. Bland-Altman revealed a good agreement of the two methods. However, mean DCT values were on average 0.8+/-1.1 mmHg higher than GAT values. A significant correlation was observed between GAT and CCT (r2=0.15, p=0.006), but not between DCT and CCT (r2=0.032, p=0.21). CONCLUSIONS: Short- and long-term reproducibility of DCT is comparable to that of GAT. GAT is more affected by CCT than DCT, measuring higher IOPs in eyes with higher central corneal thickness.     

Comparison of Goldmann applanation tonometry, rebound tonometry and dynamic contour tonometry in normal and glaucomatous eyes

AIM: To compare the intraocular pressure (IOP) measurements obtained with the rebound tonometry (RT), dynamic contour tonometry (DCT) and Goldmann applanation tonometry (GAT) in normal and glaucomatous eyes and investigate the effects of central corneal thickness (CCT) and corneal curvature (CC) on IOP measurements. METHODS: One hundred and twenty-four eyes of 124 subjects were enrolled in this cross-sectional study. Fifty-six of participants were healthy individuals and 68 of them were glaucomatous patients. IOP was measured on each subject always in the same order, ICare RT-Pascal DCT-GAT, after a minimum interval of 10min between measurements. CCT and CC were measured using a rotating Scheimpflug camera before the IOP measurements in all subjects. One way repeated measures ANOVA, Pearson correlation coefficient and regression analysis, and Bland-Altman analysis was used for the statistical assessment. RESULTS: Mean IOP for all enrolled eyes was 16.00±3.80 mm Hg for GAT, 16.99±4.91 mm Hg for RT, and 20.40±4.44 mm Hg for DCT. Mean differences between GAT and RT was -1.75±3.41 mm Hg in normal (P<0.001) and -0.37±3.00 mm Hg in glaucomatous eyes (P=0.563). Mean differences between GAT and DCT was -4.06±3.42 mm Hg in normal (P<0.001) and -4.67±3.12 mm Hg in glaucomatous eyes (P<0.001). GAT and RT were significantly positive correlated with CCT in normal (r=0.317, P=0.017 and r=0.576, P<0.001, respectively) and glaucomatous eyes (r=0.290, P=0.016 and r=0.351, P=0.003, respectively). DCT was also significantly positive correlated with CCT in normal eyes (r=0.424, P=0.001) but not in glaucomatous eyes (r=0.170, P=0.165). All tonometers were unaffected by CC. CONCLUSION: IOP measurements by RT and DCT were significantly higher than GAT. DCT has highest IOP measurements among these tonometers. RT was most influenced tonometer from CCT although all tonometers were significantly positive correlated with CCT except DCT in glaucomatous eyes. CC did not influence IOP measurements.     

The relative effects of corneal thickness and age on Goldmann applanation tonometry and dynamic contour tonometry

AIMS: To establish the effects of central corneal thickness (CCT) on intraocular pressure (IOP) measured with a prototype Pascal dynamic contour tonometer (DCT), to evaluate the effect of CCT and age on the agreement between IOP measured with the Pascal DCT and Goldmann applanation tonometer (GAT), and to compare the interobserver and intraobserver variation of the DCT with the GAT. METHODS: GAT and DCT IOP measurements were made on 130 eyes of 130 patients and agreement was assessed by means of Bland-Altman plots. The effect of CCT and age on GAT/DCT IOP differences was assessed by linear regression analysis. Interobserver and intraobserver variations for GAT and DCT were assessed in 100 eyes of 100 patients. RESULTS: The mean difference (95% limits of agreement) between GAT and DCT was -0.7 (-6.3 to 4.9) mm Hg. GAT/DCT IOP differences increased with thicker CCT (slope 0.017 mm Hg/microm, 95% CI 0.004 to 0.03, r2 = 0.05, p = 0.01), and with greater age, slope 0.05 mm Hg/year (95% CI 0.012 to 0.084, r2 = 0.05, p = 0.01). The intraobserver variability of GAT and DCT was 1.7 mm Hg and 3.2 mm Hg, respectively. The interobserver variability was (mean difference (95% limits of agreement)) 0.4 (-3.5 to 4.2) mm Hg for GAT and 0.2 (-4.9 to 5.3) mm Hg for DCT. CONCLUSIONS: GAT is significantly more affected than DCT by both CCT and subject age. The effect of age suggests an age related corneal biomechanical change that may induce measurement error additional to that of CCT. The prototype DCT has greater measurement variability than the GAT.     

动态轮廓眼压计与Goldmann压平眼压计及非接触眼压计测量眼压的对比研究

目的探讨动态轮廓眼压计(DCT)与Goldmann压平眼压计(GAT)及非接触眼压计(NCT)测量眼压的准确性,并比较三种眼压计测量结果与中央角膜厚度(CCT)的相关性。设计前瞻性、比较性病例系列。研究对象连续选取90例(90眼)10~76岁正常人。方法采用KONAN非接触式角膜内皮镜测量CCT后,对所有入选者单眼以随机顺序采用Pascal型DCT、GAT及Topcon型NCT测量眼压。测量结果两两比较,并将眼压值与CCT进行直线回归分析。主要指标眼压值,Pearson相关系数。结果 90例正常人DCT眼压平均值(17.33±2.71 mm Hg)明显高于GAT(14.27±2.81 mm Hg)(P=0.000)及NCT(14.67±2.93 mm Hg)(P=0.000),平均差异分别为(3.06±2.01)mm Hg和(2.67±2.20)mm Hg;GAT与NCT之间平均差异为(-0.39±2.29)mm Hg(P=0.105)。DCT与GAT眼压值之间相关系数r=0.736(P=0.000);与NCT眼压值之间相关系数r=0.699(P=0.000)。GAT、NCT眼压值与CCT均明显相关(r=0.370,P=0.000;r=0.508,P=0.000);DCT眼压值与CCT无明显相关性(r=0.051,P=0.639)。DCT和GAT的差值与年龄无明显相关性(r=0.064,P=0.052)。结论 DCT测量的眼压值虽高于GAT及NCT,但不受CCT的影响,可能较GAT和NCT测量的眼压值更接近真实值。     

Comparison of dynamic contour tonometry and Goldmann applanation tonometry in relation to central corneal thickness in primary congenital glaucoma

Background

To compare intraocular pressure (IOP) measurements obtained with dynamic contour tonometer (DCT) and Goldmann applanation tonometer (GAT), and to investigate their relationship to central corneal thickness (CCT) in primary congenital glaucoma (PCG) eyes.

Methods

Thirty-one eyes of 31 PCG patients (25.7?±?7.2 years old) were examined. PCG was defined as elevated IOP, enlarged corneal diameter (buphthalmos), Haab’s striae and abnormal findings at gonioscopy. The mean of three measurements of GAT, DCT (quality scores 1 and 2), and CCT were obtained and assessed for agreement by means of Bland–Altman plot and for Spearman correlation test.

Results

Mean CCT was 534?±?72.3 μm (range: 430 to 610 μm). Mean IOP measurements were 15.1?±?4.2 mmHg (range: 5.5 to 22.7 mmHg) for DCT and 14.5?±?5.6 mmHg (range: 7.0 to 34.0 mmHg) for GAT (P?=?0.244). Spearman correlation tests showed that IOP difference (DCT ? GAT) was not correlated with CCT (r ²?=?0.023, P?=?0.417). IOP measurements by DCT were weakly but statistically correlated with those obtained with GAT (r²?=?0.213, P?=?0.0089). Bland–Altman analysis revealed poor agreement between DCT and GAT readings, considering the 95 % confidence intervals of ±10.45 mmHg.

Conclusions

The differences between DCT and GAT readings were not influenced by CCT in this series of patients. Considering the weak correlation and the poor agreement observed between GAT and DCT measurements and that they both may be affected by corneal biomechanical changes, these methods should not be used interchangeably, and may possibly give no meaningful IOP values in PCG patients.     

Dynamic contour tonometry: a new way to assess intraocular pressure in ectatic corneas

PURPOSE: To compare intraocular pressure (IOP) measurements in patients with keratoconus (KC), pellucid marginal degeneration (PMD), and unilateral penetrating keratoplasty (PK) for KC by Goldmann applanation tonometry (GAT), Tono-Pen tonometry (TP), and Pascal dynamic contour tonometry (DCT). METHODS: Patients with KC, PMD, or PK were included in a prospective study. IOPs were measured by GAT, TP, and DCT. Severity of ectasia was determined by the steep curvature by corneal topography and central thinning by contact ultrasound pachymetry. IOP measurements were compared and correlated with disease severity. RESULTS: Fifty-three eyes of 36 patients were enrolled. Mean age was 45.3 +/- 12.5 years (range: 28-72 years). Twenty-nine eyes had KC, 21 eyes had a PK for KC, and 3 eyes had PMD. Mean DCT, GAT, and TP readings were 16.1 +/- 2.9, 14.3 +/- 4.1, and 13.8 +/- 4.1 mm Hg, respectively. The differences of mean IOP between GAT and DCT and TP and DCT were statistically significant, whereas the difference between GAT and TP was not. Both GAT and TP readings were significantly higher in the PK eyes than the KC and PMD eyes, whereas DCT readings were not. DCT measurements were not significantly different in PK versus non-PK eyes. CONCLUSION: DCT is a newly Food and Drug Administration (FDA)-approved device that is designed to measure IOP, independent of corneal thickness, corneal curvature, and ocular rigidity. DCT gave significantly higher IOP readings than GAT and TP in this study. DCT readings were not affected by corneal thickness. DCT may be more accurate in IOP measurement in eyes with KC and PMD.     

The effect of contact lens-induced corneal edema on Goldmann applanation tonometry and dynamic contour tonometry

Purpose  To evaluate the effect of contact lens-induced corneal edema on intraocular pressure (IOP) measurements using Goldmann applanation tonometry (GAT) and dynamic contour tonometry (DCT) in Asian subjects. Participants  The study included 40 eyes of 20 normal volunteers with no evidence of ocular disease. Methods  Forty eyes of 20 healthy volunteers were required to wear soft contact lenses for 2 hours to induce corneal swelling. Central corneal thickness (CCT) and IOP were measured before and immediately after contact lens wear using specular microscope, GAT, and DCT. The IOP measurements by GAT and DCT were compared. The changes in the CCT and the IOP measurements after wearing contact lenses were assessed. Results  The mean CCT of the 40 eyes evaluated was 532.6 ± 31.6 μm. The mean IOP was 11.78 ± 2.04 mmHg for the GAT and 14.46 ± 1.89 mmHg for the DCT, and the difference was statistically significant (P < 0.001). After wearing contact lenses, the mean CCT was 553.2 ± 34.3 μm, which was 20.6 ± 12.9 μm greater than before wearing them (P < 0.001). The mean IOP measurements of the GAT and DCT were decreased after wearing the contact lenses. The mean decrease of the GAT values was 0.43 ± 1.95 mmHg, which was not statistically significant (P = 0.175). However, the mean decrease of the DCT readings, which was 0.75 ± 1.74 mm Hg, was statistically significant (P = 0.010). Conclusion  The IOP measurements with DCT were significantly higher than those with GAT in healthy Asian eyes. Although the mean IOP measurements of both the GAT and the DCT were decreased in the edematous cornea, IOP measurements of the DCT were more affected by corneal edema than were the GAT. The authors have no proprietary, commercial, or financial interests in any of the products described in this study.     

Comparison of the rebound tonometer with the Goldmann applanation tonometer in glaucoma patients

PURPOSE: To determine the agreement between the measurement of intraocular pressure (IOP) by the rebound tonometer (RBT) and by the Goldmann applanation tonometer (GAT) and to find out the effect of central corneal thickness (CCT) values on IOP measurements in glaucoma patients. METHODS: IOP was measured with the RBT and GAT, respectively, in 61 eyes of 61 glaucoma patients. CCT was measured using an ultrasonic pachymeter after all IOP determinations had been made. The mean IOP measurement by the RBT was compared with the measurement by the GAT, by Student's t-test. Bland-Altman analysis was performed to assess the clinical agreement between the two methods. The effect of CCT on measured IOP was explored by linear regression analysis. RESULTS: The mean patient age was 56.7+/-21.1 years (range: 30-80 years). There were 32 (52.46%) women and 29 (47.54%) men in the study group. The mean IOP readings were 18.70+/-4.76 mmHg using the RBT, and 18.27+/-3.49 mmHg using the GAT. The difference was not statistically significant (mean difference 0.43+/-2.55, P=0.2). A frequency distribution of the differences demonstrated that in more than 80% of cases the IOP readings differed by <2.3 mmHg between the RBT and GAT. There was a strong correlation between the RBT and GAT readings (r=0.852, P<0.0001). The IOP measurements with the two methods were correlated with CCT (r=0.40, P=0.02 for the RBT and r=0.48, P<0.0001 for the GAT). The IOP increased 1.1 mmHg and 8 mmHg for every 100-microm increase in CCT for the GAT and RBT, respectively. CONCLUSION: The RBT slightly overestimated the IOP value by 0.43 mmHg on average when compared with the GAT. Nevertheless, the RBT readings appeared to be more affected by the various thicknesses of different corneas when compared with those obtained using the GAT.     

Reproducibility of dynamic contour tonometry. Comparison with TonoPenXL and Goldmann applanation tonometry - a clinical study on 323 normal eyes

BACKGROUND: The PASCAL Dynamic Contour Tonometer (DCT) is a new diagnostic approach for the digital measurement of intraocular pressure (IOP) in eyes with glaucoma. The aim of this study was to evaluate the reproducibility of DCT in normal eyes and to compare DCT with Goldmann applanation tonometry (GAT) and TonoPenXL. PATIENTS AND METHODS: A prospective cross-sectional study on 323 normal, consecutive eyes was performed. Eyes with an IOP of more than 23 mmHg (GAT) were excluded. Central corneal power (Zeiss Ophthalmometer) and central corneal thickness (ultrasound pachymetry: Tomey AL-1000) were taken. The IOP readings were obtained as follows: 3 x DCT [quality of measurement, IOP and ocular pulse amplitude (OPA) were taken], 1 x TonoPenXL, GAT, finally: once again DCT to evaluate the tonography effect. RESULTS: The quality of 3 following IOP (DCT) readings was good (quality Q1 = 43.4 %, Q2 = 32.5 %, Q3 = 22.7 %). The reproducibility of the IOP (DCT) measurements was excellent (first measurement IOP (DCT) = 18.1 +/- 3.4 mmHg, second measurement IOP (DCT) = 18.1 +/- 3.4 mmHg, third measurement IOP (DCT) = 17.8 +/- 3.4 mmHg, Cronbach's alpha = 0.976). First and second IOP (DCT) values showed a strong correlation (r = 0.93). A significant tonography effect was observed between first and third IOP (DCT) measurements (0.4 mmHg; p = 0.004). Mean OPA (DCT) was 3.0 mmHg during the first three measurements (Cronbach's alpha = 0.964). IOP (DCT) and OPA (DCT) reproducibility showed no laterality. IOP (DCT) (17.7 +/- 3.4 mmHg) was significantly higher than IOP (TonoPenXL) (16.0 +/- 3.2 mmHg, n = 275; p < 0.001) and higher than IOP (GAT) (14.5 +/- 3.1 mmHg, n = 275; p < 0.001). The effect of tonography between the third and last IOP (DCT) measurement was zero (p = 0.6). IOP (DCT) and IOP (GAT) values were only weak correlated with central corneal thickness. CONCLUSIONS: IOP and OPA values measured with the DCT are extraordinary reproducible in normal eyes. Frequently, DCT detects higher IOP values than those obtained with TonoPenXL and GAT. A reproducible measurement of IOP and OPA may open new diagnostic fields, e. g., in glaucoma detection or ocular vascular diseases.     

Intraocular pressure measurements using dynamic contour tonometry after laser in situ keratomileusis

PURPOSE: Thinning of the corneal stroma by laser in situ keratomileusis (LASIK) results in inaccurate low intraocular pressure (IOP) readings by Goldmann applanation tonometry (GAT). Dynamic contour tonometry (DCT) is a novel measuring technique, designed to measure IOP largely independent of corneal thickness and curvature. The purpose of this study was to compare IOP measurements using GAT and DCT in eyes undergoing LASIK for correction of myopia. METHODS: In a prospective, single-center study, central corneal thickness (CCT) and IOP were measured in patients undergoing first-time LASIK for myopia. IOP was measured before and after surgery using GAT and DCT. The untreated contralateral eyes served as paired controls. RESULTS: There was good concordance between the two tonometers in 62 normal eyes before LASIK. Corneal ablation of 90.0 +/- 49.18 micro m (median +/- SD) reduced IOP readings as measured by GAT by 3.0 +/- 1.9 mm Hg (P < 0.001). In contrast, no significant change in IOP readings was recorded by DCT (-0.2 mm Hg +/- 1.5 mm Hg, P = 0.30). There was no change in IOP in the untreated control eyes as measured by GAT and DCT. CONCLUSIONS: Significant decreases in IOP were recorded by GAT after LASIK for myopia. Measurements by DCT, however, did not reveal any significant changes in IOP.     

Comparison of intraocular pressure measured by Pascal dynamic contour tonometry and Goldmann applanation tonometry

AIMS: To compare the intraocular pressure (IOP) measurements obtained using the Pascal dynamic contour tonometer (PDCT) with the standard Goldmann applanation tonometer (GAT) and to correlate these with central corneal thickness (CCT) in patients with normal corneas. METHODS: A prospective, masked, comparative case series of 116 eyes from patients attending a glaucoma clinic. IOP was measured with PDCT by one examiner and with GAT by a masked, independent examiner. A mean of six CCT readings was used for analysis. RESULTS: IOP measured by the two instruments correlated significantly (r=0.77; P<0.0001). IOP measured by GAT correlated strongly with CCT (r=0.37, P=0.0001) whereas the relationship between IOP measured by PDCT and CCT approached significance (r=0.17, P=0.073). The differences between GAT and PDCT measured IOP also correlated strongly with CCT (r=0.37, P<0.0001). The 95% limits of agreement between GAT and PDCT were +/-4.2 mmHg. Dividing the eyes into three groups on the basis of CCT, demonstrated those in the thickest tertile showed a poorer agreement between instruments and the GAT measured significantly higher IOP in this group (P=0.003) while the PDCT showed no significant differences with different CCTs (P=0.37). CONCLUSION: Demonstration of the relative independence of PDCT IOP measurements from CCT supports a potential clinical role for this instrument, particularly for subjects with CCT outside the normal range.     

PASCAL动态轮廓眼压计临床应用的初步报告

目的:验证动态轮廓眼压计(DCT)的临床性能。方法:对81例143眼青光眼及可疑病例青光眼患者用DCT测量眼内压(IOP);132眼同时用Goldmann压平眼压计(GAT)测量眼压,部分病例同时用NIDEKUP-1000型角膜测厚仪测量中央角膜厚度(CCT)。GAT与DCT测量结果采用配对t检验,GAT、DCT测量值与CCT的关系及DCT测量值与眼脉动振幅(OPA)的相关关系采用Spearman双变量相关分析。结果:①DCT和GAT测得的眼压均数分别为(18.6±3.9)mmHg和(17.4±4.1)mmHg;DCT测得的眼压值高于GAT,其差值均数为(1.1±2.3)mmHg;两种眼压计测得的眼压值呈正相关(r=0.83,P<0.01)。②116眼同时完成了DCT眼压测量及CCT测量,两者相关系数r=0.03,P=0.77;113眼同时完成了GAT眼压测量及CCT测量,两者相关系数r=0.28,P=0.003。③143眼同时记录了DCT眼压值和眼脉动振幅(OPA),其均数分别为(18.6±3.9)mmHg和(2.6±1.1)mmHg,两者的相关系数r=0.32,P<0.01。结论:以上结果初步证实:①DCT眼压计测量值与GAT眼压测量值高度相关,但DCT测量值略高于GAT测量值,提示DCT可用于临床诊断。②DCT测量值与CCT不相关,GAT测量值与CCT显著相关,提示DCT在青光眼诊断中有独特优势。③DCT测量的OPA与IOP值显著相关,相关的机制及临床意义有待探讨。