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.     

The relationship between central corneal thickness and Goldmann applanation tonometry

Background: The aim of this study was to investigate the relationship between Goldmann applanation tonometry and central corneal thickness in a large sample of healthy eyes. Method: Five hundred eyes of 500 subjects (253 women, 50.6 per cent and 247 men, 49.4 per cent) were analysed in a prospective healthy population study. Mean age of the sample was 31 ± 8 years. Goldmann applanation tonometry was carried out by one physician. Tonometric values were the mean of three consecutive readings. Subsequently, another physician carried out ultrasonic pachymetry with the DGH 2000 AP ultrasonic pachymeter (DGH Technology Inc, San Diego, USA). Ten measurements were made at the centre of the cornea of each eye. The lowest value was used for analysis. Results: Applanation tonometry and central corneal thickness were correlated (r = 0.184, p < 0.001). There was no significam correlation between corneal thickness and age (r = 0.083, p = 0.065), mean spherical equivalem refraction (r = 0.083, p = 0.065) or visual acuity (r = 0.036, p = 0.187). Conclusion: In normal eyes, there is no statistically significant correlation between changes of intraocular pressure and changes of central corneal thickness but they suggest a relationship between intraocular pressure and central corneal thickness. Goldmann applanation tonometry has a systematic error in accuracy of intraocular pressure readings of healthy eyes caused by its dependence on central corneal thickness. Measurement of corneal thickness by optometrists should be the first step in diagnosing intraocular pressure pathologies.     

Comparison of Goldmann applanation and dynamic contour tonometry measurements: effects of corneal morphometry

ObjectivesTo compare intraocular pressure (IOP) measurements made by Goldmann applanation tonometry (GAT) and dynamic contour tonometry (DCT).MethodsIOPs were measured by GAT and DCT in 63 eyes of 63 healthy subjects. A comparison was made by intraclass correlation coefficient. Passing-Bablok plot was constructed to establish the existence of systematic and/or proportional biases. Multivariate regression analysis was used to examine whether the measurements of both instruments were affected by the power of the steepest and flattest corneal axes, their orientation, age or central corneal thickness (CCT).ResultsThe intra-class correlations (ICCs) were 0.57 (95% confidence interval (95% CI): 0.29-0.74). Mean differences were 1.68 (DCT minus GAT) (95% CI: 0.92-2.44). Passing-Bablok analysis (X=DCT, Y=GAT) revealed a systematic bias (A=-14.35, 95% CI: -24.51-[-9.14]) and a proportional bias (B=1.74, 95% CI: 1.43-2.26). Multivariate regression analysis revealed that the DCT was independent of the corneal characteristics analysed while GAT was biased by CCT (B=0.042, 95% CI: 0.002-0.082).ConclusionsWhile GAT was biased by corneal CCT; DCT readings were independent of corneal morphometry.     

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.     

The effect of Goldmann applanation tonometry on automated static threshold perimetry

Automated static threshold perimetry was performed in both eyes of 10 normal and 12 ocular hypertensive subjects treated with a topical beta-blocker, before and after Goldmann applanation tonometry of their right eyes. Both objective statistical comparison and subjective evaluation of the resultant visual fields showed no detrimental effect on visual field test results after applanation tonometry.     

The effect of contact lens induced oedema on the accuracy of Goldmann tonometry in a mature population

Aim

To determine the effect of contact lens induced oedema on the accuracy of Goldmann tonometry measurements of intraocular pressure (IOP) in mature subjects.

Methods

22 healthy subjects aged between 50 and 60 years were recruited. Corneal curvature, IOP, and central corneal thickness (CCT) were measured before and after two hours of monocular closed eye wear of a thick hydroxyethyl methacrylate (HEMA) contact lens. Measurements were then repeated at 20 minute intervals for one hour after lens removal.

Results

Both CCT (+54.1 μm) and IOP (+2.7 mm Hg) increased significantly after lens wear (p<0.001, paired t test with Bonferroni correction). For the hour following lens removal, the measured IOP was correlated to the increase in CCT (r = 0.84, p<0.001), at a rate of 1.0 mm Hg/10 μm (95% confidence interval, 0.8 to 1.2 mm Hg/10 μm, linear mixed model analysis).

Conclusions

A relatively small increase in CCT from contact lens induced corneal oedema caused an overestimation error in Goldmann tonometry measurements of IOP in healthy mature subjects.     

Comparison of rebound tonometry with Goldmann applanation tonometry and correlation with central corneal thickness

BACKGROUND/AIMS: Rebound tonometry (RT) is performed without anaesthesia with a hand held device. The primary aim was to compare RT with Goldmann applanation tonometry (GAT) and to correlate with central corneal thickness (CCT). The secondary aim was to prove tolerability and practicability of RT under "study conditions" and "routine practice conditions." METHODS: In group 1 (52 eyes/28 patients), all measurements were taken by the same physician, in the same room and order: non-contact optical pachymetry, RT, slit lamp inspection, GAT. Patients were questioned about discomfort or pain. In group 2 (49 eyes/27 patients), tonometry was performed by three other physicians during routine examinations. RESULTS: RT was well tolerated and safe. Intraocular pressure (IOP) ranged between 6 mm Hg and 48 mm Hg. No different trends were found between the groups. RT tended to give slightly higher readings: n = 101, mean difference 1.0 (SD 2.17) mm Hg; 84.1% of RT readings within plus or minus 3 mm Hg of GAT; 95% confidence interval in the Bland-Altman analysis -3.2 mm Hg to +5.2 mm Hg. Both RT and GAT showed a weak positive correlation with CCT (r2 0.028 and 0.025, respectively). CONCLUSIONS: RT can be considered a reliable alternative for clinical screening and in cases where positioning of the head at the slit lamp is impossible or topical preparations are to be avoided.     

Goldmann applanation tonometry after intacs corneal ring segments(1)

PURPOSE: To evaluate the change of intraocular pressure (IOP) after implantation of Intacs (KeraVision) corneal ring segments using Goldmann applanation tonometry (GAT). SETTING: Multicenter clinical trial for U.S. Food and Drug Administration application conducted at 10 U.S. sites. METHODS: One-year follow-up data from a phase III clinical trial (n = 359) were reviewed. Intraocular pressure was measured by GAT preoperatively and 1 week and 1, 3, 6, and 12 months after Intacs implantation. The untreated fellow eyes were controls. Change from baseline (preoperative) IOP was calculated and tested for correlation with age and change from baseline in mean keratometry, manifest refraction spherical equivalent (MRSE), and pachymetry (central corneal thickness). Mean IOP in treated and control groups was compared through month 6. RESULTS: At all postoperative examinations, mean IOP in the Intacs eyes was significantly lower (-0.39 to -1.75 mm Hg; all P 相似文献   

Comparison of Proview phosphene tonometry with Goldmann applanation tonometry

BACKGROUND: To compare intraocular pressures obtained using a handheld pressure phosphene tonometer (PPT) (Proview, Bausch & Lomb Pharmaceuticals, Inc., Tampa, Fla.) with Goldmann applanation tonometry. METHODS: Comparative case series of 30 randomly selected patients. RESULTS: The readings obtained with the pressure phosphene tonometer display a higher mean and a larger standard deviation than those obtained with the Goldmann applanation tonometer (GAT). Differences between PPT and GAT readings tended to decrease as a function of increased Goldmann levels. The relation of Proview and Goldmann readings (r = 0.32) and the scatterplot were not consistent with the hypothesis that the 2 methods are equivalent. INTERPRETATION: Our results indicate that the pressure phosphene-type handheld tonometry method, which does not appear to provide an accurate and consistent measure of intraocular pressure, is substantially less reliable than the Goldmann method.     

Ocular response analyzer versus Goldmann applanation tonometry for intraocular pressure measurements

PURPOSE: To establish correlations between intraocular pressure (IOP) measurements obtained with the ocular response analyzer (ORA) and the Goldmann applanation tonometer (GAT). The effects of central corneal thickness on the measures obtained were also examined. METHODS: This was a cross-sectional study. IOP was determined in 48 eyes of 48 patients with glaucoma In all patients, central corneal thickness (CCT) was measured by ultrasound pachymetry. RESULTS: ORA readings were consistently higher than GAT measurements (Goldmann-correlated IOP - IOP GAT mean difference, 7.2 +/- 3.5 mm Hg; corneal-compensated IOP - IOP GAT mean difference, 8.3 +/- 4.0 mm Hg) However, differences were not constant and increased with increasing IOP GAT readings, both with respect to Goldmann-correlated IOP (slope = 0.623, P < 0.0001) and corneal-compensated IOP (slope = 0.538, P < 0.0001). Both pressure measurements provided by the ORA showed significant correlation with CCT (CCT versus Goldmann-correlated IOP: r = 0.460, P = 0.001; CCT versus corneal-compensated IOP: r = 0.442, P = 0.001). No significant effects of corneal curvature or refraction on any of the pressures were observed. CONCLUSIONS: The ORA significantly overestimates IOP compared with the GAT. Differences between both sets of measures increase as the GAT-determined IOP increases. ORA readings seem to be affected by central corneal thickness.     

Clinical evaluation of applanation resonance tonometry: a comparison with Goldmann applanation tonometry

PURPOSE: The purpose of this study was to calibrate and evaluate the precision of the new applanation resonance tonometry (ART) in a clinical study designed in accordance with the International Standard Organization's requirements. METHODS: This was a prospective, randomized, single-center study, where healthy volunteers and patients participated. A total of 153 eyes were divided into 3 groups with respect to their intraocular pressure (IOP) at screening: <16 mm Hg, 16 to 23 mm Hg, and >23 mm Hg. IOP was measured with Goldmann applanation tonometry (GAT) as reference method and by ART in both a biomicroscope (ARTBiom) and a handheld (ARTHand) setup with a 10-minutes pause between methods. The mean of 6 readings was regarded as one measurement value. RESULTS: Mean age of the subjects was 59 years (range 20 to 87 y). GAT showed a mean IOP of 20.0 mm Hg (range 8.5 to 43.5 mm Hg, n=153). The precision was 2.07 mm Hg for ARTBiom and 2.50 mm Hg for ARTHand, with a significant dependency for age as compared with GAT. Measurement order produced a decreasing IOP with a mean of 2.3 mm Hg between the first and last method. CONCLUSIONS: The precision obtained in both ARTBiom and ARTHand was within the limits set by the International Standard Organization standards for tonometers. The standardized procedure and the stability of the biomicroscope setup resulted in a slightly better precision as compared with the handheld setup. Despite a 10-minutes pause between measurements, the order was a significant factor, possibly because the patients were more apprehensive at the first measurement.     

不同角膜厚度下动态轮廓眼压计和Goldmann压平眼压计在不同角膜厚度的测量值比较

目的比较动态轮廓眼压计（dynamic contour to-nometry,DCT）和Goldmann压平眼压计（Goldmann applanation tonometry,GAT）在中央角膜厚度（central corneal thickness,CCT）不同的正常眼测量值的差异。方法患者69例（69眼）按CCT不同分为正常组（520～580μm）42眼、变薄组（450～520μm）16眼、增厚组（580～640μm）11眼。各组分别用DCT和GAT测量眼压。结果正常组平均CCT为（574.55±16.40）μm,平均GAT值为（16.62±3.15）mmHg（1kPa=7.5mmHg）,平均DCT值为（16.78±2.86）mmHg,DCT与GAP差异无统计学意义（P〉0.05）,平均GAT-DCT值为（-0.16±0.96）mmHg;变薄组平均CCT为（499.44±16.70）μm,平均GAT值为（14.03±2.72）mmHg,平均DCT值为（17.06±2.72）mmHg,2者差异有统计学意义（P〈0.01）,平均GAT-DCT值为（-3.03±1.32）mmHg;增厚组平均CCT为（605.18±17.90）μm,平均GAT值为（16.91±3.94）mmHg,平均DCT值为（16.80±4.25）mmHg,2者差异无统计学意义（P〉0.05）,平均GAT-DCT值为（0.05±2.47）mmHg。结论在角膜厚度正常眼,DCT值和GAT值较一致;在角膜厚度变薄眼,前者较后者准确;在角膜厚度变厚眼未体现DCT的优越性。     

Goldmann applanation tonometry in the conscious rat

PURPOSE: To determine whether the Goldmann applanation tonometer can be modified to measure intraocular pressure (IOP) in the conscious rat. METHODS: In anesthetized rats Goldmann tonometers were tested that had reduced biprism angles in the applanating tips and reduced weights in the tonometer body from those used in humans and species with similar size eyes. Tonometers with tips with biprism angles of 48 degrees and an applied weight of 25 mg per Goldmann scale division (2 g full scale) were calibrated for the rat against manometrically measured IOP. Tonometers, thus modified, were then used in conscious, unsedated rats. RESULTS: In conscious rats the measured mean Goldmann value was 15.5 +/- 0.6 mm Hg (confidence interval = 14.1, 16.6 mm Hg). This was the plateau level reached after the repeated applanations (approximately 10) required to eliminate an artifactual decline in initial Goldmann readings, which was larger than that in humans. CONCLUSIONS: The Goldmann applanation tonometer was modified to measure IOP in the conscious, unsedated rat. This instrument, the standard for measuring this key physiological parameter in the human eye, can now be applied to the laboratory rat. This may advance the use of this important animal as a model in IOP and glaucoma research.     

Digit preference in Goldmann applanation tonometry: the hedgehog effect

PURPOSE: Digit preference is a subconscious bias towards numbers that end in certain digits. We conducted a study to assess for digit preference in intraocular pressure measurement using the Goldmann applanation tonometer. DESIGN: Prospective study with masked and unmasked phases. METHODS: The study was conducted in general ophthalmic clinics in a District General Hospital in Blackpool, United Kingdom, by 6 clinical ophthalmologists. Consecutive right eye intraocular pressure measurements were collected for a 2-month period for the masked phase and were repeated for the unmasked phase. The proportion of even numbers was the main outcome measure. RESULTS: Six ophthalmologists completed both phases: 555 of 917 readings were even in the masked phase (P = .075), and 679 of 1056 readings were even in the unmasked phase (P = .022). CONCLUSIONS: Our results suggest that digit preference influences measurements from the Goldmann applanation tonometer and that this persists when observers are aware of digit preference. This bias may influence both clinical decision-making and trial results.     

中央角膜厚度及屈光度对压平眼压计测量值的影响

目的 探讨中央角膜厚度(CCT)以及屈光状态对Goldmann压平眼压计(GAT)测量值的影响.方法 应用OCT3测量正常人121例(199只眼)与近视患者81例(159只眼)的CCT,用Goldmann压平眼压计测量眼压,比较两组之间CCT和眼压测量值的差异,分析CCT与眼压测量值的关系.结果 正视组平均CCT值为(525.05±32.83)μm,眼压的均值为(12.91±2.26)mmHg;近视组平均CCT值为(524.85±29.76)μm,眼压的均值为(14.23±2.54)mmHg;两组的CCT值比较差异无显著性(t=-0.600,P=0.952),两组的眼压值比较差异有显著性(t=-5.139,P＜0.001).高度近视眼CCT偏薄,眼压随屈光度数较少而增加,近视组眼压与屈光度相关(r=-0.296,P＜0.001),屈光度数每增加-4.05D,眼内压升高1 mmHg.正视组(r=0.317,P＜0.001)和近视组(r=0.341,P＜0.001)的眼压与CCT相关,眼压校正公式分别为1 mmHg/45.45 μm、1 mmHg/34.48 μm.结论 CCT可以影响Goldmann压平眼压计测量值,屈光状态也可以影响眼压值,高度近视眼的眼压建议用从近视人群中获得的眼压校正公式校正.