Agreement of non-contact pachymetry after LASIK: comparison of combined scanning-slit Placido disc topography and specular microscopy
Purpose To assess the interchangeability of central corneal thickness (CCT) measurements between combined scanning-slit/Placido disc topography (Orbscan-II) and specular microscopy (Topcon SP-2000P) in patients who underwent laser in situ keratomileusis (LASIK) for myopia. Patients and methods We re...
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Published in | Eye (London) Vol. 24; no. 6; pp. 1064 - 1070 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
London
Nature Publishing Group UK
01.06.2010
Nature Publishing Group |
Subjects | |
Online Access | Get full text |
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Summary: | Purpose
To assess the interchangeability of central corneal thickness (CCT) measurements between combined scanning-slit/Placido disc topography (Orbscan-II) and specular microscopy (Topcon SP-2000P) in patients who underwent laser
in situ
keratomileusis (LASIK) for myopia.
Patients and methods
We recruited 118 consecutive patients who underwent LASIK for myopia. The CCT was measured using Orbscan-II and Topcon SP-2000P randomly. Orbscan-II and Topcon SP-2000P CCT data were analysed using the paired-sample
t
-test and the limits of agreement (LoA) were calculated with the method described by Bland–Altman.
Results
The average CCT measurements by Orbscan-II and Topcon SP-2000P were 447.55±49.78
μ
m and 461.38±35.35
μ
m, respectively (
P
<0.0001; mean difference, 13.83±22.31
μ
m; 95% confidence interval, 9.77–17.09
μ
m). The Bland–Altman plot showed an inverse association between the average and the difference between the devices: Topcon–Orbscan-II=174.23 –0.353 × Average (
P
<0.01). The widths of the crude and regression-based 95% limits of agreement were 87.45 and 63.72
μ
m, respectively.
Conclusions
Orbscan-II measurements of CCT after myopic LASIK were significantly lower than those obtained using Topcon SP-2000P. The limits of agreement between the two devices were too broad and, therefore, both pachymetric values cannot be used interchangeably. Further, the tendency towards comparably Orbscan-II readings in thinner corneas precludes that one technique can directly replace the other. This is important for the adequate medium- and long-term follow-up of the growing LASIK patient population. |
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Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-News-1 ObjectType-Feature-3 content type line 23 |
ISSN: | 0950-222X 1476-5454 |
DOI: | 10.1038/eye.2009.233 |