Article

Repeatability and Reproducibility of Pachymetric Mapping with Visante Anterior Segment Optical Coherence Tomography

Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, 00, Hong Kong
Investigative Ophthalmology &amp Visual Science (Impact Factor: 3.66). 01/2008; 48(12):5499-504. DOI: 10.1167/iovs.07-0591
Source: PubMed

ABSTRACT To determine the repeatability and reproducibility of central and peripheral corneal pachymetry mapping with anterior segment-optical coherence tomography (AS-OCT).
An observational cross-sectional study involving two groups: 27 healthy eyes and 20 eyes with keratoconus. Each subject underwent scanning sessions with AS-OCT to determine intraobserver repeatability, interobserver reproducibility, and additionally for healthy eyes, intersession reproducibility for different regions of the cornea up to a 10-mm diameter. Main outcome measures were reproducibility and repeatability coefficients, intraclass correlation coefficients, and coefficients of variation of the average central (0-2 mm), pericentral (2-5 mm), transitional (5-7 mm), and peripheral (7-10 mm) corneal thicknesses generated by the Visante AS-OCT (Carl Zeiss Meditec, Inc., Dublin, CA) pachymetric mapping protocol.
The coefficients of repeatability were less than 2% in healthy subjects and less than 3% in patients with keratoconus. The reproducibility coefficients were less than 2% and 4% in healthy subjects and patients with keratoconus, respectively. There was no significant difference between scans obtained by different observers or during different visits. The intraclass correlation coefficients were greater than 0.99 and 0.97 in healthy subjects and patients with keratoconus, respectively.
With the pachymetric mapping protocol of Visante AS-OCT, these results suggest that central and peripheral corneal thickness measurements in healthy subjects and in eyes with keratoconus are repeatable and reproducible.

0 Followers
 · 
117 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To assess accuracy and repeatability of central corneal thickness (CCT) measurements obtained by swept-source anterior segment optical coherence tomography (AS-OCT), spectral-domain retinal OCT with corneal module and ultrasound pachymetry (USP), and to assess repeatability of pachymetric mapping with AS-OCT. 50 healthy volunteers were recruited. A single, experienced operator analysed the right eye of each participant twice in the same session with AS-OCT ('corneal map' routine), retinal OCT and USP. CCT measurements were compared using repeated-measures analysis of variance, Bonferroni test, Pearson correlation and Bland-Altman plots. Repeatability of thickness maps and CCT measurements were assessed using Alpha of Cronbach, intraclass correlation coefficient (ICC) and coefficient of repeatability. Mean CCT±SD was 540±28.9 μm for AS-OCT, 544±29.5 μm for retinal OCT and 549.3±31.7 μm for USP; the differences were statistically significant (p<0.01). CCT measurements obtained with the three instruments were highly correlated: r was 0.965 for AS-OCT/USP, 0.962 for retinal OCT/USP and 0.984 for AS-OCT/retinal OCT comparison. The repeatability of CCT measurements was higher for AS-OCT than for the other devices (p<0.001). Repeatability of pachymetric maps was excellent (ICC=0.999). Pachymetric maps by swept-source AS-OCT showed excellent repeatability. CCT measurements obtained by AS-OCT, USP and retinal OCT were highly correlated although not identical.
    Acta ophthalmologica 06/2012; 90(6):e452-7. DOI:10.1111/j.1755-3768.2012.02453.x · 2.51 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This copy of the thesis has been supplied on condition that anyone who consults it is understood to recognise that its copyright rests with its author and that no quotation from the thesis and no information derived from it may be published without proper acknowledgement.
  • [Show abstract] [Hide abstract]
    ABSTRACT: A description is given of the design of a broadband downconverter to cover both 4-GHz and 6-GHz common carrier bands. The downconverter was tested as a replacement for the downconverter in both the MDR-2204 and MDR-2306 4-GHz and 6-GHz radio systems, respectively. Excellent results have been observed in both radio systems. In threshold bit error rate (BER) tests, the downconverter provided 1.2-dB better performance than both radio systems. In overload BER tests, the downconverter showed a 0.5-dB better performance. The features credited for the good performance are: (1) the noise figure of the low-noise amplifier is less than 1.7 dB over the band; (2) the phase noise of the local oscillator is quite low; (3) the two-tone third-order intercept point of the downconverter is above 26 dBm; and (4) the image rejection is greater than 20 dB over the band.
    Microwave Symposium Digest, 1988., IEEE MTT-S International; 01/1988

Preview

Download
0 Downloads
Available from