Axial length is the distance between the cornea on its epithelial side and the foveola of the retina, along the visual axis. It's essential to determine this variable whenever an intraocular lens is being calculated after having eliminated an optical element from the eye.

Any refractive consequence of an error in the calculation of axial length is significant, even more so when the aim of crystalline lens surgery is to achieve emmetropia.

Axial length is measured using ocular biometry. We calculate this using an optical biometer: IOL Master.

Using a non-contact technique, the IOL Master takes measurements via an optical system called partial coherence interferometry, measuring an anterior-posterior axis coinciding with the visual axis.

To carry out a biometric measurement, patients are normally placed in front of high precision equipment which sends a laser signal to record how images are captured.

In general, patients do not need any special preparation for this examination.