Influence of operator experience on the performance of ultrasound biometry compared to optical biometry before cataract surgery

Purpose: To compare measurements performed with the IOLMaster (Carl Zeiss, Meditec AG) with those obtained by applanation ultrasound (US) and manual keratometry and to evaluate the effect of operator experience on US biometry. Setting: Department of Ophthalmology, University of Vienna, Vienna, Austria. Methods: The axial length (696 eyes) and anterior chamber depth (ACD) (462 eyes) were measured in 377 patients with cataract using the IOLMaster and applanation US. To assess the effect of operator experience on the biometric results, the operators were divided into 2 groups: experienced and less experienced in performing US biometry. The difference in measurements between the methods and the variability of the difference were compared between the 2 groups. Results: Applanation US measured axial length and ACD shorter than the IOLMaster; the mean numerical difference was 0.13 mm and 0.19 mm, respectively (P<.01). For axial length, the absolute difference was smaller with experienced operators than with less experienced operators (0.15 mm versus 0.22 mm) (P<.01). For ACD, experienced operators obtained a smaller difference between measurement techniques (0.21 mm versus 0.29 mm; P<.05). Conclusions: Experienced US operators had less difference and lower variability in the difference between applanation US and IOLMaster readings for axial length and ACD measurements. The noncontact optical method, which is essentially operator independent, gave significantly more reliable biometry before cataract surgery, especially in the case of less experienced operators.