Ultrasound Biomicroscopy (UBM)
Ultrasound biomicroscopy is an eye examination that provides a detailed image of your eye. It uses high-frequency sound waves (ultrasound) to generate images of the inside of the eye. Ultrasound biomicroscopy is most commonly used to assess causes of glaucoma (damage of optic nerves), cysts, tumours, foreign objects in the eye and extent of trauma.
During the examination, you will be asked to lie down in a supine (face up) position. Your examiner will apply topical anaesthesia to the eye before scanning. A small coupling device is placed on the service of the eye which is filled with saline to create a “water bath”. The probe of the ultrasound is then placed in this water bath in close proximity to the eye. Ultrasound biomicroscopy generates cross-sectional or transverse images of the following structures of the eye:
- Cornea: transparent, dome-shaped layer covering the front of the eye
- Sclera: white portion of the eye
- Iris: thin, circular structure that regulates the amount of light that enters into the eye
- Anterior chamber angle: angle formed between the iris and the cornea
- Ciliary body: releases transparent fluid called aqueous humour, which maintains normal eye pressure
The images help your doctor to understand the structural pattern of the eye and diagnose any abnormalities or problems.