Eye biometry

Publication date: 26.08.2019

Biometric examination enables measurement of axial length of the eye and the distance between several eye structures.
Currently two biometric methods are used:

  • Ultrasound biometry uses ultrasound waves to measure the distance between several eye structures. It is a contact method, that means, it requires contact of ultrasonic transducer with patient’s eye. (ultrasound)
  • Optic biometry does not require direct contact with the eyeball. It is based on optical coherence tomography (OCT) technique.

How to prepare for the examination?

You should remove make-up and contact lenses before the examination. The examination is performed after administration of anaesthetic eye drops, as the probe end is applied to the eye surface. The doctor should be informed about potential allergy to anaesthetics. The patient should sit or lie down calmly. If the patient sees light inside the probe, he/she should look directly into it. If the patient does not see the light, s/he should look straight in the distance with the other eye. No sudden movement with the head should be made or moving the head without doctor’s orders. During the examination and directly after it, it is possible to have a slightly blurred vision.

Ultrasound in A-mode projection

During the examination the length and the eyeball and particular structures inside the eye are evaluated. This computer method enables the doctor to calculate strength of intraocular lens during qualification to cataract removal surgery and to measure parameters like anterior chamber length, corneal thickness, axial length of the eye. Examination is performed with a biometer head touching the surface of the eye. The examination is based on making a quick series of measurements. The results are visible to the doctor as an average value received from the measurements.

The examination is painless, requires cooperation between the patient and the doctor and lasts only several seconds.

Indications for the examination

  • Measurement of the axial length of the eye
  • Measurement of the strength of intraocular lens that is inserted after removal of severe cataract
  • Monitoring of high myopia progression
  • Measurement of anterior chamber length and/or corneal thickness
  • Measurement of extraocular muscles
  • Measurement of intraocular neoplasms and/or orbital cavity neoplasms
  • Assessment of reflectivity of several eyeball structures

What conditions after the examination should make you contact the doctor?
You should see the doctor if the eye is very red, the redness lasts longer than one day or there is purulent discharge from the eye.

Ultrasound in B-mode projection

Ultrasound examination helps to visualise inner eye structures or pathology of the eye, even in case of severe cataract that impedes examination. This examination is also helpful in case of imaging of structures outside the eyeball but inside orbital cavity. The examination is performed by a doctor, who touches closed eyelid with a transducer. The examination is painless, requires cooperation between the patient and the doctor and lasts only several seconds.

Indications for having eye and eye socket ultrasound:

  • Imaging of eye’s interior with opaque optical structures
  • Diagnostics of exudative haemorrhagic macular degeneration
  • Diagnostics of retinal detachment
  • Diagnostics of proliferative and haemorrhagic lesions in diabetes and post-traumatic changes
  • Examination of posterior segment of the eyeball in case of haemorrhage or inflammation
  • Finding intraocular foreign bodies

Desc.ription of the examination by the doctor

The examination usually lasts from a few up to several dozens of seconds. The patient is sitting with closed eyes. Eyelids are covered with small amount of a gel and ultrasonic transducer is applied to the eyelid. That enables imaging of examined structures on a screen and measuring them. The examination ends with printing all the images together with measurements. The print-outs for the referring doctor are supplemented with a desc.ription made by the doctor performing the examination.


There are no medical contraindications. The examination can be performed on patients of all ages, also pregnant women or small children and can be repeated as necessary.