Intraocular lenses (IOL) power calculation is one of the main parts of the preoperative examination of cataractous patients. In order to determine accurate IOL power, some ocular parameters should be measured through biometry devices. The most important ocular biometry parameters include the axial length (AL), the corneal curvature (K-reading), corneal diameter (white-to-white), and the anterior chamber depth (ACD).

There are two different technologies for performing ocular biometry measurements: ultrasonography and optical biometry. Ophthalmic ultrasound is an easily available, cost-effective and reliable imaging method for measuring oculometric parameters. A-mode applanation ultrasound is a contact biometry method in which the device's probe is placed directly on the corneal surface. The primary problem with the contact method is the unwanted pressure applied to the cornea during the test and can underestimate the measured AL and ACD.

In recent years, new biometric instruments based on the swept-source optical coherence tomography (SS-OCT) technology have been a non-invasive, high-sensitivity, and high-resolution medical imaging technology.

To compare the reliability and agreement of axial length (AL), anterior chamber depth (ACD), and lens thickness (LT) measurements obtained with optical biometry based on swept-source optical coherence tomography (IOLMaster 700; Carl Zeiss, Germany) and an ultrasound biometry device (Nidek; US-4000 Echoscan, Japan) in different qualities of AL measurement.

As a result of the study, it is noted that AL and ACD of the IOLMaster700 had outstanding agreements with the US-4000 ultrasound in different quality measurements of AL and can be used interchangeably. But LT should be used interchangeably cautiously only in the high-quality measurements group.

More details can be found here https://www.sciencedirect.com/science/article/pii/S1888429623000171