Exact knowledge of the length and size of the eye and its different parts is a prerequisite before deciding on an operation. While the frontal, visible, parts of the eye are easy to measure, the measurement of the length of the eye and its parts requires a precise biometrical determination.

In the Clinic Pallas we use two different methods:

Optical biometry is based on the determination of the length of the eye by partial coherence interferometry (PCI). This is a non-contact procedure. Axis length, corneal radii and depth of the anterior chamber of the patient’s eye can be measured with great precision with this device.

Important operation data can be recorded by biometry. It is mandatory for implant surgery. But it is also an important part of the examination before a laser treatment, because an implant operation might be performed later, independently of the laser treatment (for instance in case of a cataract).

Optical biometry is performed along the visual axis and is very precise; measurement errors are virtually excluded. Even for a not perfectly shaped eye, the measurement of the axis length is still possible. High-degree refraction errors, pupil diameter and accommodation condition of the eye do not influence the result of this measure.

Ultrasound biometry is another technique used to measure eye length. It is based on pressure waves, as in marine echolocation. The ultrasonic waves generated by an emitter (in the non-audible range) pass through the whole eye. By measuring the time between the emission and reception of the waves, the position of the individual parts of the eye can be determined.