Eye ultrasound: when and how it is done

Eye ultrasound is an imaging procedure that uses high frequency sound waves to create detailed images of structures within the eye and orbit. The sound waves are emitted by a transducer, bounce off the ocular tissues as echoes, and are then converted into digital images. This examination allows a doctor to assess the condition of various parts of the eye, including the retina, lens, optic nerve, and the muscles surrounding the eye.

An eye ultrasound is crucial in situations where the inside of the eye cannot be directly visualized, such as due to corneal opacity, vitreous hemorrhage, or advanced cataracts. It is used to diagnose a wide range of conditions, including retinal detachment, retinal tears, intraocular tumors like melanoma or retinoblastoma, and to assess fluid around the optic nerve in cases of increased intracranial pressure. The test can also help evaluate the position of an intraocular lens after cataract surgery or in cases of severe eye trauma.

Before the test, you may be asked to remove contact lenses. Tell the medical team about recent injuries, operations or other relevant eye conditions. Ultrasound itself usually does not require dilating drops, although the clinician may use them for a separate examination during the same visit. If dilation is planned, arrange transport and avoid driving until your vision is safe.

The test is typically performed while you are sitting or lying down. After local anesthetic drops are applied to the eye, a special gel is placed on the eyelid or directly on the white of the eye. The transducer is gently placed on the area and moved in various directions to scan all parts of the eye. You may be asked to move your eye in different directions during the examination. The test itself usually takes about 15 minutes and is not painful, though it may cause slight discomfort due to the pressure from the transducer.

There are two main types of eye ultrasound: B scan for the posterior segment and Ultrasound Biomicroscopy (UBM) for the anterior segment. The B scan is used to image the retina, choroid, optic nerve, and orbit, aiding in the diagnosis of retinal detachment, tumors, and hemorrhages. UBM provides high resolution images of the front part of the eye, including the cornea, iris, ciliary body, and drainage angle, making it particularly useful for evaluating glaucoma, anterior segment tumors, and intraocular lens position.

Eye ultrasound does not use ionizing radiation and is generally safe when performed with appropriate equipment and technique. It can be used in children and during pregnancy when clinically indicated. However, pressure on an eye with a suspected open wound can be harmful. Tell the team about recent trauma or surgery so that an ophthalmologist can decide whether ultrasound is appropriate and choose the technique.

Ultrasound does not replace a direct retinal examination when this is possible, and a normal scan does not reliably exclude every small retinal tear. If dilating drops were used for another part of the visit, avoid driving until vision is safe. The clinician interprets the images together with the eye examination and discusses the next steps.