Purpose: To evaluate the intraobserver and interobserver variability in axial length (AL), anterior chamber depth (ACD), and corneal radius measurements using an optical biometry instrument based on partial coherence interferometry (PCI).
Setting: Johannes Gutenberg University, Mainz, Germany.
Methods: In this observational case series and interobserver reliability trial, 30 healthy, emmetropic to moderately myopic eyes of 15 volunteers were evaluated. The AL, ACD, and corneal radius were measured 20 times in 10 eyes by 1 observer to evaluate the intraobserver variability. To evaluate the interobserver variability, the measurements were taken in 20 eyes by 5 different observers. Measurements were performed using the IOLMaster (Carl Zeiss) based on PCI. The data description is based on coefficients of variation and the statistical inference on reliability estimation based on analysis of variance. The main outcome measures were intraobserver and interobserver variability and reliability in AL, ACD, and corneal radii.
Results: The intraobserver variability (SD) was +/-25.6 microm for AL, +/-33.4 microm for ACD, and +/-12.9 microm for corneal radius. The coefficients of variation were 0.1%, 0.9%, and 0.17%, respectively. The interobserver variability (SD) was +/-21.5 microm for AL, +/-29.8 microm for ACD, and +/-15.9 microm for corneal radius. The coefficients of variation were 0.09%, 0.82%, and 0.21%, respectively. The reliability was 99.9% for AL, 97.8% for ACD, and 99.8%/99.5% for corneal radius (r1/r2). The slightly reduced reliability in ACD measurement was caused by a reduced intraobserver reliability of 1 of the 5 observers (R = 0.87).
Conclusion: Partial coherence biometry using the IOLMaster for AL measurement was highly reliable, offering observer-independent measurement results.