An ocular biometry is a diagnostic test that enables us to measure the different parameters of the eye, like its axial length, i.e., the distance between the apex of the cornea and retina, and the depth of the anterior chamber, which is the space between the cornea and the crystalline lens.

It provides fundamental data for calculating the power of intraocular lenses, which is why the test is  performed on all patients who are to undergo cataract operations.

There are two types of biometry: optical ones that work with light, and A-scan ultrasounds. The latter may be contact- or immersion-based. Light or ultrasounds pass through the different structures of the eye, giving us information about the different parameters. Anaesthetic drops must be instilled to perform an ultrasound biometry, as direct contact with the patient’s cornea is involved.

Olga Riera,Visual Function Department