Comparison of Orbscan and Ultrasound pachymetry in the measurement of central corneal thickness

Radford, S W; Lim, Ridia; Salmon, John F.

doi:10.1038/sj.eye.6700669

Cited by 22 publications

(12 citation statements)

References 9 publications

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“…4–9 Most investigations of epithelial thickness report on the central cornea only. While a few studies have documented the peripheral thickness along the horizontal meridian, 10–13 very few have studied the thickness along the peripheral vertical meridian.…”

Section: Introductionmentioning

confidence: 99%

Vertical and Horizontal Corneal Epithelial Thickness Profiles Determined by Ultrahigh Resolution Optical Coherence Tomography

Wang

Cui

et al. 2012

Cornea

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Purpose To measure vertical and horizontal thickness profiles of the central and peripheral corneal epithelium and determine if daytime changes occur. Methods Forty eyes of 20 normal subjects were imaged by ultra-high resolution spectral domain optical coherence tomography to profile the corneal epithelial thickness from the edge of Bowman’s layer to the central cornea across the vertical and horizontal meridians. Measurements were made at 10:00 AM and again at 6, 8 hours later. Results The baseline vertical meridional epithelial thickness was thinnest, 42.9±4.1 μm, at the edge of Bowman’s layer in the superior region. It increased in thickness (p<0.01), towards the central cornea. The central epithelium averaged 52.5±2.4 μm, becoming thickest, 55.2±2.5 μm, in the inferior pericentral region. It thinned towards the inferior periphery, reaching 51.3±5.1 μm at the edge of Bowman’s layer (p<0.01). Along the horizontal meridian, the epithelium was thickest at the nasal side, 58.6±5.1 μm, and temporal side, 59.3±6.6 μm, near the edges of Bowman’s layer. It thinned towards the central cornea. There were no significant changes in the epithelial thickness at any location over 8 hours. Conclusion Epithelial thickness varied over the horizontal and vertical meridians and appeared stable during the daytime.

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Section: Introductionmentioning

confidence: 99%

Vertical and Horizontal Corneal Epithelial Thickness Profiles Determined by Ultrahigh Resolution Optical Coherence Tomography

Wang

Cui

et al. 2012

Cornea

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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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“…It has recently been reported that the order of measurement by different ultrasonic pachymeters has no effect on thickness. 26 The Orbscan II measurements, in eyes without previous corneal surgery (group 1), were found to be comparable with those of the three tested ultrasound instruments, differing from the findings of Radford et al 9 Fakhry et al 25 found no difference, even in post-LASIK eyes. One possible reason for a difference in these and other reports is the acoustic level setting.…”

Section: Discussionmentioning

confidence: 73%

Section: Purposementioning

confidence: 99%

“…A review of methods for measuring CCT with a range of thickness and the impact of CCT on measuring intraocular pressure was recently reported by Doughty and Zaman 7 using a meta-analysis. The most common method to determine CCT is ultrasonic pachymetry, which has been claimed by some authors 8,9 to be the gold standard.The clinical care of patients who undergo corneal refractive surgery and glaucoma risk assessment and management often involve being examined at more than one office location. Because different pachymeters can be used at different offices, it is important to know how comparable these different instruments are.…”

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confidence: 99%

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Comparison of Central Corneal Thickness Measured by Four Different Pachymeters

Myrowitz¹,

Ren²,

Chuck³

2007

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

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In 45 consecutive patients tested on one visit by the same clinician, CCT measured with three ultrasonic pachymeters, including two hand-held units, was clinically comparable in group 2. CCT measured with two ultrasonic pachymeters (i.e., PachMate and PachPen) was clinically comparable in group 1. The Orbscan II data differ from the other three instruments in both groups but more in the patients who had undergone LASIK (group 2).

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Comparison of Orbscan and Ultrasound pachymetry in the measurement of central corneal thickness

Cited by 22 publications

References 9 publications

Vertical and Horizontal Corneal Epithelial Thickness Profiles Determined by Ultrahigh Resolution Optical Coherence Tomography

Vertical and Horizontal Corneal Epithelial Thickness Profiles Determined by Ultrahigh Resolution Optical Coherence Tomography

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

Comparison of Central Corneal Thickness Measured by Four Different Pachymeters

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