Corneal thickness measurements: scanning-slit corneal topography and noncontact specular microscopy versus ultrasonic pachymetry☆
Accepted 17 January 2003.
Abstract
Purpose
To compare central corneal thickness measurements taken with 3 pachymetry systems: Orbscan scanning-slit corneal topography/pachymetry, Topcon SP2000P noncontact specular microscopy, and Tomey ultrasonic pachymetry.
Setting
Multicenter study, Tokyo, Japan.
Methods
In 216 healthy eyes of 114 subjects, scanning-slit topography, noncontact specular microscopy, and ultrasonic pachymetry were used in that sequence to record central corneal thickness. In another 20 healthy eyes of 13 subjects, 2 sets of measurements were repeated for each pachymetry to assess repeatability.
Results
The mean central corneal thickness was compatible between scanning-slit topography (546.9 μm ± 35.4 [SD] ) and ultrasonic pachymetry (548.1 ± 33.0 μm); however, noncontact specular microscopy gave a significantly smaller mean (525.3 ± 31.4 μm) than the other 2 tests (P<.001, Tukey multiple comparison). There were significant linear correlations between scanning-slit topography and noncontact specular microscopy (r = 0.846, P<.001), noncontact specular microscopy and ultrasonic pachymetry (r = 0.897, P<.001), and ultrasonic pachymetry and scanning-slit topography (r = 0.852, P<.001). Noncontact specular microscopy tended to show the best repeatability; however, the difference was not statistically significant (P = .663, repeated-measure analysis of variance).
Conclusions
Corneal thickness readings were comparable between scanning-slit topography and pachymetry; noncontact specular microscopy gave significantly smaller values. The measurements of the 3 methods showed significant linear correlations with one another. All methods provided acceptable repeatability of measurements.
aDepartment of Ophthalmology, University of Tokyo School of Medicine (Suzuki, Amano, Araie), Tokyo, Japan
Reprint requests to Tetsuro Oshika, MD, Department of Ophthalmology, Institute of Clinical Medicine, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8575, Japan.
☆ None of the authors has a financial or proprietary interest in any material or method mentioned.
ABSTRACT