Purpose To compare biometric measures from 2 modern swept-source OCT biometers (IOLMaster700
(Z, Carl-Zeiss-Meditec) and Anterion (H, Heidelberg Engineering)) and evaluate the
effect of measurement differences on the resulting lens power (IOLP). Methods Biometric
measurements were made on a large study population with both instruments. We compared
axial length (AL), central corneal thickness (CCT), anterior chamber depth (ACD),
lens thickness (LT) and corneal front and back surface curvature measurements. Corneal
curvature was converted to power vectors and total power derived using the Gullstrand
formula. A paraxial lens power calculation formula and a prediction for the IOL axial
position according to the Castrop formula were used to estimate differences in IOLP
targeting for emmetropia. Results There were no systematic differences between measurements
of AL (- 0.0146 +/- 0.0286 mm) and LT (0.0383 +/- 0.0595 mm), whereas CCT yielded
lower (7.8 +/- 6.6 mu m) and ACD higher (0.1200 +/- 0.0531 mm) values with H. With
H, CCT was lower for thicker corneas. The mean corneal front surface radius did not
differ (- 0.4 +/- 41.6 mu m), but the corneal back surface yielded a steeper radius
(- 397.0 +/- 74.6 mu m) with H, giving lower mean total power (- 0.3469 +/- 0.2689
dpt). The astigmatic vector components in 0 degrees/90 degrees and 45 degrees/135
degrees were the same between both instruments for the front/back surface or total
power. Conclusion The biometric measures used in standard formulae (AL, corneal front
surface curvature/power) are consistent between instruments. However, modern formulae
involving ACD, CCT or corneal back surface curvature may yield differences in IOLP,
and therefore, formula constant optimisation customised to the biometer type is required.
