Abstract | PURPOSE: SETTING: METHODS: Central corneal thickness (CCT) was measured in 101 eyes of 59 normal subjects and in 30 eyes of 21 post- LASIK patients. Measurements were made with an Orbscan slit-scanning elevation topographer and immediately afterward with an ultrasound pachymeter. RESULTS: The difference in mean CCT between ultrasound (538.0 microm +/- 36.7 [SD]) and Orbscan (566.6 +/- 40.7 microm) pachymetry was statistically significant (P <.001) in the normal eyes; the Orbscan measurement was approximately 28 microm higher than that of the ultrasound pachymeter. The difference in mean CCT between the ultrasound and the slit-scanning techniques was also statistically significant in the post- LASIK eyes (mean values 475.3 +/- 50.3 microm and 461.9 +/- 74.2 microm, respectively; P <.0001). Differences in CCT in individual subjects were much more variable in the post- LASIK eyes than in the normal eyes. The Bland and Altman method for assessing clinical agreement between 2 instruments showed that in 95% of cases, the CCT measurements with both instruments would be within 65 microm in normal eyes and 150 microm in post- LASIK eyes. CONCLUSION: Central corneal thickness measurements were, on average, 28 microm higher with the Orbscan than with the ultrasound pachymeter in normal eyes and 13 microm lower in post- LASIK eyes. The degree of variability within each group indicated that these 2 techniques are not clinically comparable, precluding interchangeable use of their data in planning or assessing corneal surgery.
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Authors | H S Chakrabarti, J P Craig, A Brahma, T Y Malik, C N McGhee |
Journal | Journal of cataract and refractive surgery
(J Cataract Refract Surg)
Vol. 27
Issue 11
Pg. 1823-8
(Nov 2001)
ISSN: 0886-3350 [Print] United States |
PMID | 11709257
(Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)
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Topics |
- Adult
- Cornea
(diagnostic imaging, surgery)
- Corneal Topography
- Humans
- Keratomileusis, Laser In Situ
- Myopia
(diagnostic imaging, surgery)
- Prospective Studies
- Surveys and Questionnaires
- Ultrasonography
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