What is ocular biometry and what is it used for?

04/02/2026

Ocular biometry is an essential diagnostic test in ophthalmology that is used to measure the dimensions of the eye with great precision.

The main parameters measured by ocular biometry are:

• Axial length of the eye: distance between the cornea and the retina
• Anterior chamber depth: space between the posterior surface of the cornea and the anterior surface of the crystalline lens
• Lens thickness
• Corneal curvature

We can basically distinguish two types of biometry depending on the technique used to take the measurements:

• Optical biometry: the most commonly used. It uses laser technology or coherent light to perform the measurement. It is fast and non-invasive, and is especially useful in eyes with transparent ocular media.
• Ultrasound biometry: uses ultrasound to perform the measurement. It is especially useful when dealing with eyes with opaque corneas or very dense cataracts in which the light from the optical biometer cannot penetrate. Since there is contact with the cornea, it requires instillation of topical anesthesia to perform the test.

What is ocular biometry used for?

Ocular biometry is mainly used to:

• Calculate the power of the intraocular lens that will be implanted in cataract surgery.
• Assess ocular anatomy in cases of myopia, hyperopia, or other abnormalities.
• Monitor eye growth in children or in myopia progression studies.

Olga Riera, diagnostic tests at Centro de Oftalmología Barraquer