Comparison of Axial Length Measurements with the Use of Optical Biometry (IOL Master 700) and Ultrasound Biometry (A‐scan 550 Sonomed)

Abstract

Purpose: To compare measurements of axial length obtained with A-scan and IOL Master. The study was design to collect the axial length values resulting from the application of both methods on the same eye (R.E.) and then to compare them.
 Methodology Place and Duration of Study: 50 healthy patients selected randomly after visiting the clinic for daily routine examination. at the general hospital of Athens “Korgialenio – Benakio” were invited to participate in the study. The study took place in collaboration of University of West Attica Dept Biomedical Science Course Optics & Optometry with the general hospital of Athens “Korgialenio – Benakio”. Axial length measurements were obtained both by contact ultrasound (A‐scan 550 Sonomed, Lake Success, NY, USA) and by non‐contact laser interferometry (IOL Master 700 SWEPT Source Biometry). Two sets of measurements were repeated by a single examiner for each method.
 Results: A total of 50 eyes in 50 patients were evaluated. All participants volunteer to participate in this study. Estimates of axial length obtained with the two techniques were highly correlated. Axial lengths obtained with the contact method (mean 24.23mm, SD 1.64mm) were lower than those obtained with the non‐contact method (mean 23.29mm, SD 1.59mm) and the difference was not statistically significant (p = 0.150). The coefficient of variation was lower with non‐contact laser interferometry (6.58%) than with the ultrasound technique (6.76%).
 Conclusion: Similar estimates of axial length are obtained using contact and non‐contact techniques, with the latter producing higher measurements results than the former. The A-scan and the non‐contact laser interferometry device (IOL Master 700) provide both reproducible results with similar the accuracy of measurements of axial length in the clinical setting.