Increased Corneal Thickness Simulating Elevated Intraocular Pressure

Johnson, Mark W.; Kass, Michael A.; Moses, Robert A.; Grodzki, Walter J.

doi:10.1001/archopht.1978.03910050360012

Cited by 186 publications

(83 citation statements)

References 4 publications

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“…31 The mean CCT value of our cohort of patients was lower than that reported by other studies for OHT subjects. 32,33 Considering that a substantial number of OHT patients tend to have an overestimation of GAT IOP based on a thicker cornea, 34 the significance of the CCT value as predictor for POAG development could be related to the proportion of false-positive OHT patients included in the study. Moreover, IOP and CCT values are related and this could have masked the real effect of both parameters in predicting POAG conversion.…”

Section: Discussionmentioning

confidence: 99%

Baseline factors predicting the risk of conversion from ocular hypertension to primary open-angle glaucoma during a 10-year follow-up

Salvetat

Zeppieri

Tosoni

et al. 2016

Eye

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Section: Discussionmentioning

confidence: 99%

Baseline factors predicting the risk of conversion from ocular hypertension to primary open-angle glaucoma during a 10-year follow-up

Salvetat

Zeppieri

Tosoni

et al. 2016

Eye

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“…5 Studies comparing measurements with manometry and tonometry indicate that measuring CCT is essential to properly interpret the results obtained with a Goldmann applanation tonometer (GAT). [6][7][8] To estimate the true intraocular hydrostatic pressure from the GAT readings, several investigators have proposed some formulae, which we employed for the purposes of this study, that take CCT into account. 6,7,[9][10][11] If applying these correction formulae to the Ocular Hypertension Treatment Study cohort, the proportion of subjects with a baseline IOPr21 mmHg in the randomly chosen eye at entry would be 52%, which would be only 10% if uncorrected by these formulae.…”

Section: Introductionmentioning

confidence: 99%

Varying Effects of Corneal Thickness on Intraocular Pressure Measurements with Different Tonometers

Liu

Hsu

2004

Eye

109

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Aims To compare the intraocular pressure (IOP) measurements using the Goldmann applanation tonometer (GAT), noncontact tonometer (NCT), and ocular blood flow tonometer (OBFT), and to evaluate the effects of varying central corneal thickness (CCT) on the readings. Methods Ultrasound pachymetry and tonometry were performed on 170 eyes. Using the corrected GAT values that took CCT into account as the standard, we calculated the NCT and OBFT measurement errors related to the CCT variable by a linear regression model. Group comparisons were performed with the v 2 test and one-way ANOVA test. The correlation between the various tonometer measurements was analysed by Pearson's correlation method. Results Both the NCT (r ¼ 0.872, Po0.001) and OBFT measurements (r ¼ 0.861, Po0.001) were highly correlated with the GAT measurements. IOP measurements using the three tonometers were all correlated with CCT (all Po0.001), with the NCT measurements showing the greatest regression coefficient (b ¼ 0.063, r ¼ 0.650) and the GAT measurements the least (b ¼ 0.037, r ¼ 0.496). A linear regression model indicated that a 10 lm change in CCT resulted in a NCT measurement deviation of 0.47-0.98 mmHg and an OBFT measurement deviation of 0.29-0.81 mmHg.Conclusion Pressure readings with the GAT, NCT, and OBFT are all affected by CCT, with the NCT being the one most affected and the GAT the least. Our findings suggest CCT an essential variable to consider in interpreting IOP readings, especially for the NCT measurements.

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“…[2][3][4] It has been known for some time that interindividual variation in central corneal thickness (CCT) influences intraocular pressure (IOP) measurement. [5][6][7][8][9] Orssengo and Pye 10 using an engineering approach to the cornea have developed a tabulated algorithm for calculating a 'true' IOP. The process modifies a Goldmann tonometry reading, taking into account CCT and, to a lesser extent, corneal curvature.…”

Section: Introductionmentioning

confidence: 99%

Repeatability and reproducibility of the BVI ultrasonic Pachymeter

Gunvant

Broadway

Watkins

2003

Eye

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Purpose To evaluate the interobserver and intraobserver reliability of a commercially available, portable, ultrasonic pachymeter. Methods For the interobserver variability study, 42 healthy subjects underwent repeated ultrasonic pachymetry under topical anaesthesia performed by two observers. For the intraobserver study, another 30 further healthy subjects underwent repeated pachymetry by one of the observers. Agreement was analysed by means of Bland-Altman plots and by determination of the intraclass correlation coefficient. Results For the interobserver variability study, the mean measurement difference between observers was 0.7 lm (95% CI À0.8-2.2 lm) and the intraclass correlation coefficient was 0.9958 (95% CI 0.9922-0.9977). The Bland-Altman plot showed narrow limits of agreement with respect to central corneal thickness (CCT). For the intraobserver variability study, the mean difference between the repeated measurements was 0.9 lm (95% CI À3.1-1.3 lm). The intraclass correlation coefficient was 0.9934 (95% CI 0.9863-0.9969). A Bland-Altman plot again showed narrow limits of agreement with respect to CCT. The mean CCT for 72 subjects was 538 lm (95% CI 528-545 lm). Conclusions Measurements of CCT using the BVI Pocket Pachymeter were repeatable and had excellent interobserver reliability. Measurement variation amounted to less than 0.2% assuming a mean CCT of 538 lm.

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Increased Corneal Thickness Simulating Elevated Intraocular Pressure

Cited by 186 publications

References 4 publications

Baseline factors predicting the risk of conversion from ocular hypertension to primary open-angle glaucoma during a 10-year follow-up

Baseline factors predicting the risk of conversion from ocular hypertension to primary open-angle glaucoma during a 10-year follow-up

Varying Effects of Corneal Thickness on Intraocular Pressure Measurements with Different Tonometers

Repeatability and reproducibility of the BVI ultrasonic Pachymeter

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