Effect of central corneal thickness on Goldmann applanation tonometry measures—a different result with different pachymeters

Doughty, Michael J.; Jonuscheit, Sven

doi:10.1007/s00417-007-0601-x

Cited by 15 publications

(11 citation statements)

References 21 publications

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“…However, as this acrossstudy analysis shows, just because some studies have reported what might seem to be a substantial agreement (e.g., between adjusted mean corneal thickness values or even in correlation analyses), it is not consistent. These analyses further support a case made previously, [43][44][45][46] that the use of a so-called AF does not align Orbscan pachymetry data to that obtained by U/S pachymetry. More recent studies 55 also show that the Orbscan pachymetry, with or without a correction factor, does not obviously align Orbscan corneal thickness data to that of another optical technique of specular microscopy.…”

Section: Discussionsupporting

confidence: 85%

The Orbscan Acoustic (Correction) Factor for Central Corneal Thickness Measures of Normal Human Corneas

Doughty

Jonuscheit

2010

Eye &Amp; Contact Lens: Science &Amp; Clinical Practice

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Orbscan pachymetry can be expected to yield CCT data that is approximately 7% higher than U/S. The global application of a 0.92 AF does not robustly align the Orbscan CCT data to that of U/S and, in fact, can easily result in the data being as much as 7% lower. Overall, the level of agreement between Orbscan and U/S is limited, and Orbscan data should simply be reported as measured without any adjustment.

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Section: Discussionsupporting

confidence: 85%

The Orbscan Acoustic (Correction) Factor for Central Corneal Thickness Measures of Normal Human Corneas

Doughty

Jonuscheit

2010

Eye &Amp; Contact Lens: Science &Amp; Clinical Practice

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“…Although there is limited evidence that long-term use of topical hypotension medications are associated with lowered IOP and very slight reduction in CCT, 33 the predominant IOP-CCT interaction is that of differences in CCT resulting in differences in the outcome of tonometry. 2 Although this effect can be substantial and can be readily demonstrated with Orbscan pachymetry, 34 it is not logical to consider IOP to be a determinant of CCT in generally healthy eyes. 2 For this reason, IOP was not considered in the multivariate regressions.…”

Section: Iovsmentioning

confidence: 99%

Evidence for a Relative Thinning of the Peripheral Cornea with Age in White European Subjects

Jonuscheit

Doughty

2009

Invest. Ophthalmol. Vis. Sci.

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“…Several studies have been made comparing Orbscan with ultrasound pachymetry for measurement of corneal thickness, some of which are summarized in Table 1 4, ,9,10,11,12,13,14,15,16,17,18,19. From the Table, considerable variability is seen in comparison of mean CCT for groups of normal eyes when comparing ultrasound pachymetry with Orbscan measurements (using the manufacturer’s recommended acoustic correction factor of 0.92), with differences ranging from −21 to 33 µm.…”

Section: Introductionmentioning

confidence: 99%

Central corneal thickness measured by the Orbscan II system, contact ultrasound pachymetry, and the Artemis 2 system

Paul

Lim

Starr

et al. 2008

Journal of Cataract and Refractive Surgery

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Purpose-To compare central corneal thickness measurements obtained by Orbscan II, contact ultrasound pachymetry and the non-contact Artemis-2 scanning ultrasound system. Methods-The central corneal thickness of 40 eyes (20 normal subjects) was measured using first the Orbscan II, followed by contact ultrasound pachymetry, and finally by the Artemis-2. Results were compared statistically using ANOVA, paired T-tests, and Bland-Altman plots.Results-One-way ANOVA showed a significant difference between the three different modes of measuring central corneal thickness (F=32.84, p=0.0001). Artemis-2 and the ultrasound pachymeter measurements were highly correlated (R 2 =0.963, p<0.0001), but with Artemis, on average, measuring central corneal thickness by 11.2±6.6 microns less than the pachymeter. The Artemis-2 and Orbscan II measurements were less well correlated (R 2 =0.851, p<0.001), with Orbscan measurements on average 7.5±15.7 microns thinner than those obtained with the Artemis-2. In addition, the Orbscan showed a trend towards increasing underestimation of corneal thickness for thinner corneas.Conclusions-Ultrasound pachymetry and Artemis-2 measurements of central corneal thickness were highly correlated. The 11-micron mean difference between the pachymeter and Artemis measurements may be attributed to decentration, oblique incidence of the probe to the cornea or possibly the effect of topical anesthetic when using contact pachymetry. While Orbscan values only had an average difference of 7.5 microns from Artemis, they were less correlated than contact ultrasound pachymetry with Artemis values and increasing prone to underestimation of corneal thickness for thinner corneas.

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Effect of central corneal thickness on Goldmann applanation tonometry measures—a different result with different pachymeters

Abstract: Orbscan measures of the thickness of a central corneal zone can be used to assess the impact of central corneal thickness on Goldmann tonometry data.

Cited by 15 publications

References 21 publications

The Orbscan Acoustic (Correction) Factor for Central Corneal Thickness Measures of Normal Human Corneas

The Orbscan Acoustic (Correction) Factor for Central Corneal Thickness Measures of Normal Human Corneas

Evidence for a Relative Thinning of the Peripheral Cornea with Age in White European Subjects

Central corneal thickness measured by the Orbscan II system, contact ultrasound pachymetry, and the Artemis 2 system

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