Ultrasound (ie: B-Scan) Testing and Your Eyes

Background on Ultrasound

The procedure of an ultrasound is well known from its uses in pregnancy and other medicine. However, the same technology is used on the eyes.

An ultrasound is scan that uses very high frequency sound waves to scan into the body.

This type of sound wave is not heard or felt but allows for an image to be formed based on the return of the sound off of structures in the body.

Safety of Ultrasounds B-Scans

Ultrasounds are one of the most frequently used imaging types due to the overwhelming safety of the procedure.

Having been around for many years, ultrasound technology provides a very low risk means of viewing inside the body.

Additionally, ultrasounds are available and quick and typically do not require a separate office visit or appointment.

Ultrasound on the Eye

Just like on a pregnant woman’s stomach, a transducer and gel are used to perform an ultrasound on the eye.

With the eyelid closed, the provider performing the ultrasound will apply the transducer directly to the eyelid with a small amount of the gel on the end of the transducer.

This procedure is very painless and does not require any anesthetic.

To obtain a view of the back of the eye, the provider will instruct the patient to look in a specific direction. This allows the ultrasound to scan in the appropriate direction.

An ultrasound on the eye will only take a few minutes to perform and does not have any lasting side effects. The gel can be removed with a tissue or cleansing wipe.

When Would You Need a B-Scan? 

There are multiple reasons to have an ultrasound on the eyes. Some common reasons include a dense cataract, a large hemorrhage or abnormalities in the vitreous, drusen on the optic nerve, or determining the axial length of the eye.

Ultrasound for a Dense Cataract

If a patient has a cataract that prevents the doctor from viewing the retina in the back of the eye, an ultrasound may be indicated before a referral for surgical removal.

The importance of assessing the health of the retina before attempting a surgical procedure is due to optimal outcomes.

If the retina is not healthy or intact, vision may not improve following a cataract extraction surgery.

For this reason, it is common that an ultrasound of the eye be used if the retina cannot be viewed in an exam.

Intraocular Hemorrhage or Abnormality in Vitreous

Similar to a dense cataract, if there is a large hemorrhage or spilled blood into the vitreous of the eye, the view of the retina may be obscured.

Optic Nerve Drusen

A common finding in an eye exam is optic nerve drusen. This is a benign finding that is typically monitored and not treated.

However, the optic nerve drusen may mimic many other conditions which require additional treatment such as optic nerve swelling or papilledema.

An ultrasound can help distinguish optic nerve drusen due to the bright reflection of the drusen in the ultrasound images.

Determining the Length of the Eye (Axial Length)

The length of the eyeball is called the axial length. This is an important factor in determining the prescription power of the eye as the longer the eye is the more powerful the glasses will be needed.

In some cases, nearsightedness can be prevented from progressing and a common measurement in these cases is the axial length.

An ultrasound can help to measure the axial length of the eye and can be used to monitor changes due to progression.

When You Need an Ultrasound on Your Eye

An ultrasound of the eye is a useful procedure but is only used for specific needs. An eye doctor will determine if an ultrasound is the correct option for you.