Intraocular pressure and ocular pulse amplitude using dynamic contour tonometry and contact lens tonometry

Background

The new Ocular Dynamic Contour Tonometer (DCT), investigational device supplied by SMT (Swiss Microtechnology AG, Switzerland) allows simultaneous recording of intraocular pressure (IOP) and ocular pulse amplitude (OPA). It was the aim of this study to compare the IOP results of this new device with Goldmann tonometry. Furthermore, IOP and OPA measured with the new slitlamp-mounted DCT were compared to the IOP and OPA measured with the hand-held SmartLens^®, a gonioscopic contact lens tonometer (ODC Ophthalmic Development Company AG, Switzerland).

Methods

Nineteen healthy subjects were included in this study. IOP was determined by three consecutive measurements with each of the DCT, SmartLens^®, and Goldmann tonometer. Furthermore, OPA was measured three times consecutively by DCT and SmartLens^®.

Results

No difference (P = 0.09) was found between the IOP values by means of DCT (mean: 16.6 mm Hg, median: 15.33 mm Hg, SD: +/- 4.04 mm Hg) and Goldmann tonometry (mean: 16.17 mm Hg, median: 15.33 mm Hg, SD: +/- 4.03 mm Hg). The IOP values of SmartLens^® (mean: 20.25 mm Hg, median: 19.00 mm Hg, SD: +/- 4.96 mm Hg) were significantly higher (P = 0.0008) both from Goldmann tonometry and DCT. The OPA values of the DCT (mean: 3.08 mm Hg, SD: +/- 0.92 mm Hg) were significantly lower (P = 0.0003) than those obtained by SmartLens^® (mean: 3.92 mm Hg, SD: +/- 0.83 mm Hg).

Conclusions

DCT was equivalent to Goldmann applanation tonometry in measurement of IOP in a small group of normal subjects. In contrast, SmartLens^® (contact lens tonometry) gave IOP readings that were significantly higher compared with Goldmann applanation tonometer readings. Both devices, DCT and SmartLens^® provide the measurement of OPA which could be helpful e.g. for the management of glaucoma.

     

动态轮廓眼压计在正常人群中的应用及其影响因素分析

目的评价动态轮廓眼压计（DCT）与Goldmann压平眼压计（GAT）测量值之间的关系,寻找DCT眼压测量值的影响因素;分析DCT所测眼压脉动振幅（OPA）与DCT眼压值、中央角膜厚度（CCT）、角膜屈光力（CCV）、眼轴长度（AL）、前房深度（ACD）、收缩压（SBP）、舒张压（DBP）和心率（HR）的关系。方法分别测量正常人60例60眼的DCT眼压、GAT眼压、CCT、CCV、AL、ACD以及HR、SBP、DBP等指标,比较GAT、DCT2种眼压计测量的相关性及DCT测量值的影响因素。结果 DCT与GAT所测眼压平均值分别为（16.04±2.57）mmHg和（14.20±2.93）mmHg。DCT眼压值较GAT眼压值高,差异有统计学意义（t=6.454,P〈0.01）。DCT眼压值与GAT眼压值呈正相关（r=0.684,P〈0.01）。DCT眼压值与CCT不相关（r=0.212,P=0.105）,GAT眼压值与CCT呈正相关（r=0.291,P=0.024）。60例正常人的OPA均值为（2.50±0.89）mmHg,OPA与年龄、DCT眼压值、CCT、SBP、DBP、HR均不相关（P〉0.05）,与CCV呈正相关（r=0.343,P=0.007）。结论在正常人群中DCT眼压值与GAT眼压值有较好的相关性,DCT的眼压测量值不受CCT、CCV等因素的影响。DCT眼压值、CCT、SBP、DBP、HR等对OPA无明显影响。     

Intraocular pressure measurement-comparison of dynamic contour tonometry and goldmann applanation tonometry

PURPOSE: The dynamic contour tonometer (DCT, Pascal tonometer, Swiss Microtechnology AG, Port, Switzerland) was recently introduced as a new method of intraocular pressure measurement, supposedly independent of corneal properties. In this study we analyzed the agreement and correlation of dynamic contour tonometry and Goldmann applanation tonometry (GAT) and investigated the influence of central corneal thickness (CCT) and corneal curvature. We also considered preferential patient groups for both methods. METHODS: In a prospective study of 100 eyes without glaucoma, intraocular pressure was measured using dynamic contour tonometry and Goldmann applanation tonometry, followed by measurements of central corneal thickness and corneal curvature. RESULTS: A clear correlation between dynamic contour tonometry and Goldmann applanation tonometry was found (r = 0.693; P < 0.001). Dynamic contour tonometry generally resulted in higher intraocular pressure measurements (median difference + 1.8 mm Hg, mean difference + 2.34 mm Hg). Unlike dynamic contour tonometry, Goldmann applanation tonometry was remarkably affected by central corneal thickness, but neither method was significantly influenced by corneal curvature. Bland-Altman graphs showed remarkable disagreement between dynamic contour tonometry and Goldmann applanation tonometry, which could be partially explained by the influence of central corneal thickness on Goldmann applanation tonometry. To obtain valid readings, dynamic contour tonometry required a more extensive selection of patients than Goldmann applanation tonometry. CONCLUSIONS: Dynamic contour tonometry seems to be a reliable method for intraocular pressure measurement, which unlike Goldmann applanation tonometry is not influenced by central corneal thickness. In clinical practice, advantages from dynamic contour tonometry can be expected for cooperative patients, outpatients, and patients with sufficient bilateral ocular fixation, whereas Goldmann applanation tonometry measurements are more reliable in case of patients with inadequate cooperation, poor vision, or nystagmus.     

Comparison of dynamic contour tonometry and noncontact tonometry in ocular hypertension and glaucoma

PURPOSE: To assess the agreement in the measurement of intraocular pressure obtained by dynamic contour tonometer (DCT) and noncontact tonometer (NCT) in patients with glaucoma and ocular hypertension, to investigate the effect of corneal thickness on pressure readings by both instruments, and to assess the reproducibility of dynamic contour tonometer. METHODS: NCT and DCT measurements were made on 104 eyes of 104 patients with primary open-angle glaucoma (n=75) or ocular hypertension (n=29), and agreement was assessed by means of Bland-Altman plots. The effect of corneal thickness on both tonometers was assessed by linear regression analysis. Interobserver and intraobserver variations for dynamic contour tonometer were assessed in 41 eyes of 41 patients. RESULTS: The mean difference+/-SD (95% limits of agreement) between NCT and DCT was -0.80+/-2.98 (-6.6 to 5.1) mm Hg (P=0.009) and no relation between NCT/DCT differences and average was found. The intraocular pressure readings obtained by noncontact tonometer depended on central corneal thickness (P<0.001, adjusted r(2)=0.301). However, dynamic contour tonometer readings showed no effect of corneal thickness (P=0.388, adjusted r(2)=-0.002). The coefficient of repeatability for DCT was 0.92 (95% CI 0.85-0.96, P=0.001). CONCLUSION: In subjects with primary open-angle glaucoma and ocular hypertension, NCT and DCT readings are not interchangeable. DCT measurements, unlike NCT measurements, did not depend on corneal thickness.     

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.     

Lower ocular pulse amplitude with dynamic contour tonometry is associated with biopsy-proven giant cell arteritis

Objectives

To determine the role of the ocular pulse amplitude (OPA) from Pascal dynamic contour tonometry in predicting the temporal artery biopsy (TABx) result in patients with suspected giant cell arteritis (GCA).

Ocular pulse amplitude in patients with open-angle glaucoma, normal-tension glaucoma, and ocular hypertensionby dynamic observing tonometry

PURPOSE: The aim of this study was to compare the ocular pulse amplitude (OPA) in patients with different types of glaucoma, and also to evaluate the usefulness of OPA for the elucidation of normal-tension glaucoma (NTG). OPA is thought to reflect choroidal circulation. SUBJECTS: Sixty-six patients with normal-tension glaucoma (NTG), 52 patients with primary open angle glaucoma (POAG), 42 with ocular hypertension (OH) and 68 normal controls (NC) were enrolled in this study. METHODS: OPA was measured in all participants by dynamic observing tonometry(DOT). The correlation between OPA and the following parameters [IOP, refraction error (Ref), blood pressure, pulse pressure (PP), MD of Humphrey field analyzer 30-2, type of groups] was analyzed by linear and multiple regression analysis (MRA). Multiple logistic regression analysis (MLR) was used to estimate the adjusted odds ratio (OR) for evaluation of the association between OPA (including other factors) and the proportion of NTG. RESULTS: In MRA, IOP, Ref (< -3 D), PP and type of groups were significantly associated with OPA. The OPA in NTG was significantly lower than NC (p < 0.05). MLR demonstrated that OPA [OR 0.26 (95% CI, 0.12-0.57), p = 0.001] was associated with increased risk of having NTG. CONCLUSIONS: Lower OPA in patients with NTG suggests that there is insufficiency of ocular circulation in NTG. Evaluation of OPA may be useful for the elucidation of the pathogenesis of glaucoma.     

Intraocular pressure measured by dynamic contour tonometer and ocular response analyzer in normal tension glaucoma

Background  

To investigate intraocular pressure (IOP) measurement values in normal tension glaucoma (NTG) eyes using two different types of tonometer that are supposed to be little affected by corneal biochemical properties.     

婴幼儿眼压水平及其不同眼压计测量结果比较

目的 初步了解我国婴幼儿的眼压水平,比较两种不同眼压计的测量结果.方法 选取正常或无影响眼压疾病的婴儿76例119只眼,幼儿18例27只眼,使用Perkins和Schiotz两种眼压计于异氟醚麻醉下测量婴儿眼压,于氯氨酮加异氟醚麻醉下测量幼儿眼压.结果 Perkins和Schiotz眼压计测量的婴儿眼压分别是(10.37±2.50)mmHg和(11.78±2.62)mmHg(F=15.98,P＜0.0001),幼儿眼压分别是(14.19±3.74)mmHg和(14.33±2.87)mmHg(F=0.04,P=0.8489).结论 婴儿组眼压低于幼儿组(F=60.53,P＜0.0001),幼儿组眼压较高是正常生理变化还是氯氨酮麻醉的作用,有待于进一步观察.     

Comparison of dynamic contour tonometry and Goldmann applanation tonometry and their relationship to corneal properties,refractive error,and ocular pulse amplitude

BackgroundAccurate intraocular pressure (IOP) measurement is essential in diagnosing and managing glaucoma. Dynamic contour tonometry (DCT) is less dependent on corneal properties, such as thickness, elasticity, and rigidity, than Goldmann applanation tonometry (GAT). This study examined the relationship between GAT and DCT as well as their relationship with corneal properties and ocular pulse amplitude (OPA).MethodsGAT, DCT, OPA, pachymetry, refractive error, and corneal curvature measurements were obtained on 115 healthy volunteers.ResultsParticipants with thicker corneas (≥580 μm) had higher IOP measurements with GAT than DCT (P = 0.005). Those with thinner corneas (≤520 μm) had lower IOP with GAT versus DCT (P = 0.008). GAT and DCT readings did not differ significantly in corneas with average thickness (521 to 579 μm). A clinically significant IOP difference between DCT and GAT was found in 18.2% of subjects. A correlation was found between OPA and both refractive error and IOP (R² = .343, P < 0.0001). OPA was higher with increased IOP and decreased myopia.ConclusionDCT provides IOP measurements that are less dependent on corneal factors than GAT, aiding in diagnosis and treatment of patients with ocular hypertension and glaucoma. Additional studies are necessary to examine the relationship between OPA, refractive error, and IOP and its possible association with increased incidence of glaucoma in myopic patients.     

老年人群的动态轮廓眼压计眼压及眼脉动幅度初步调查

目的:初步了解老年人群的动态轮廓眼压计(dynamic con-tour tonometer,DCT)的眼压及眼脉动幅度(ocular pulse amplitude,OPA)分布特征。方法:对一组老年人群(88例)双眼行DCT测量,记录其眼压及OPA,对获得的数据进行分组统计学分析比较。结果:受试者总体平均DCT眼压为16.57±2.87mmHg,总体平均OPA为2.37±0.83mmHg。受试者的右眼、左眼DCT平均眼压分别为16.91±2.03mmHg及16.24±3.08mmHg,双眼之间无显著统计学差异(P=0.007)。左右眼的OPA分别为2.37±0.83mmHg及2.38±0.82mmHg,双眼之间无显著统计学差异(P=0.907)。将受试者按性别分组比较均无显著统计学差异。双眼DCT眼压值的高度与OPA的大小之间无显著相关关系(右眼:r=0.206,P=0.054;左眼:r=0.121,P=0.262)。结论:初步获得DCT眼压及OPA在老年人群中的分布特征,了解到不同性别、不同眼别之间的DCT眼压及OPA无显著统计学差异,为今后DCT临床研究奠定了一定的基础。     

Comparing dynamic contour tonometry to Goldmann and hand-held tonometry in normal,ocular hypertension,and glaucoma populations

We prospectively compared dynamic contour tonometry (DCT) to Goldmann (GAT) and hand-held tonometry (HHT) in normal, ocular hypertension, and glaucoma populations. Both measurements were made on each patient within a 5-minute period during routine office exams over 4 months. While DCT is in good overall agreement with GAT and HTT, there is some systematic deviation at different pressure ranges in normal, ocular hypertension, and glaucoma populations. Disclosure The authors have stated that they do not have a significant financial interest or other relationship with any product manufacturer or provider of services discussed in this article. The authors also do not discuss the use of off-label products, which includes unlabeled, unapproved, or investigative products or devices.     

Intraocular pressure and ocular pulse amplitude variations during the Valsalva maneuver

Background  

To evaluate the effect of the Valsalva maneuver (VM) on short-term variations of intraocular pressure (IOP) and ocular pulse amplitude (OPA) values in healthy, young, male subjects.     

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.     

Comparison of dynamic contour tonometry and goldmann applanation tonometry in glaucoma patients and healthy subjects

PURPOSE: To investigate the agreement in the measurement of intraocular pressure (IOP) obtained by dynamic contour tonometry PASCAL (DCT-PASCAL) and Goldmann applanation tonometry (GAT) in glaucoma eyes and healthy eyes with different central corneal thickness (CCT). DESIGN: Prospective cross-sectional study. METHODS: In a randomized order, three consecutive IOP measurements were performed on 197 eyes of 107 subjects by one examiner using both DCT-PASCAL and GAT on all eyes. Furthermore, ultrasonic pachymetry was performed. The Spearman correlation coefficient (r) was determined to compare IOP readings between DCT-PASCAL and GAT. Regression-based Bland and Altman analysis was used to evaluate agreement between the instruments. RESULTS: Mean IOP values obtained by both instruments were significantly correlated in healthy and glaucoma eyes (all healthy eyes [n = 66]: r = 0.8, P < .001, all glaucoma eyes [n = 131]: r = 0.96, P < .001). Neither GAT nor DCT-PASCAL showed a significant correlation with CCT (GAT: all eyes: r = 0.009, P = .9, DCT-PASCAL: all eyes: r = -0.05, P = .5). Bland and Altman analysis revealed the existence of proportional bias. Thus, 95% limits of agreement between the instruments varied with the actual IOP measurement. CONCLUSIONS: DCT-PASCAL and GAT revealed a strong correlation in IOP measurements between glaucoma and healthy eyes. However, the analysis of agreement indicated some discrepancies between the instruments. Measurements with both GAT and DCT-PASCAL were not correlated with central corneal thickness.