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Good intermethod agreement seen with two imaging systems
A comparison of two imaging systems showed good intraobserver and interobserver agreement, a study found.
The study assessed the Heidelberg Retina Tomograph (HRT) II Rostock Cornea Module and the Tomey EM-3000 noncontact specular microscope.
The 48 normal subjects included in the prospective study underwent central corneal thickness (CCT) and endothelial cell density (ECD) measurements with both instruments three times each by two independent observers. Mean age of participants was 69.6 years.
Differences between instruments were not related to CCT, but a significant difference was observed with increasing ECD (P = .0001).
The mean CCT with the HRT was 536 ± 37.6 µm, and the mean CCT with the Tomey was 529.4 ± 35.4 µm. The mean ECD with the HRT was 2,539.7 ± 338.6 cells/mm2, and the mean ECD with the Tomey was 2,473.5 ± 242.2 cells/mm2.
The HRT and the Tomey both showed low intraobserver and interobserver test-retest variability for CCT and ECD measurements, although the Tomey tended to show less variability.
“Although highly correlated, these instruments should not be used interchangeably for the assessment of CCT and ECD measurements, considering that HRT II RCM showed an overall tendency to overestimate CCT and to underestimate ECD in eyes with lower cell density, yet overestimate ECD in eyes with higher cell density,” the study authors said.