Repeatability of Central Corneal Thickness Measures by Orbscan Pachymetry for Right and Left Eyes

Abstract

The results confirm excellent repeatability of Orbscan pachymetry measures in both spectacle and contact lens wearers. For the adult subjects assessed, there was no evidence of a right/left eye difference and/or a progressive change in measured thickness with time. The high similarity between right and left eye measures should be taken into account if data from both eyes are being used either in contralateral eye comparisons or in comparative studies of different pachymeters.

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

“…This selection has since been recommended for the acquisition of reliable and repeatable measurements of both central and peripheral locations. 13,19,20 Overall, slightly different results can be obtained if …”

“…As detailed elsewhere on other groups of subjects, including contact lens wearers, the repeat scans are highly reproducible with no detectable differences between the data output from successive scans. 13 From the pachymetry data output mode, 9,13 single-point thickness measurements from 17 locations (eight temporal and eight nasal locations as well as from the central point of the cornea), nominally 0.5 mm apart, were manually extracted. No correction factor was applied to the pachymetry measurements.…”

Screening of Forme Fruste Keratoconus with the Ocular Response Analyzer

“…Although the CCT measurements with US pachymetry is less variable, we chose Orbscan II slit lamp biomicroscopy to allow a good repeatability and reproducibility of measured values with an acoustic factor of 0.92 and to ensure low intraand interobserver variations. [33][34][35][36] In published data, CH and CRF had a positive and moderate correlation with CCT, but were no measurements of the same biomechanical parameters. [21][22][23][24][25][26] We found similar moderate correlation coefficients with CCT in our study.…”

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

“…For nominally normal subjects, it is likely that the intereye repeatability of corneal thickness measures is so good and so similar that combining data from both eyes could yield a false estimate of the consistency of any difference between measurement techniques. 60 Indeed, the very weak correlation between Orbscan and U/S measures when all data sets are used (r ϭ 0.351, P ϭ 0.015) could very well be due to such an effect, as no correlation was found when only studies using one eye were used for the analyses (r ϭ 0.316, P ϭ 0.174).…”