Ultrasound Sonography of Eyes

Ultrasound sonography is one of the oldest investigative tools used in the medical field. They also commonly go by the name ‘Video X-ray’ as it has a similar display as X-rays with black and white shadows. It is one of the most convenient tools that helps to visualize various layers of the eyeball in the form of echoes with black and white color.

What Is Ultrasound Sonography Of The Eye?

Ultrasound sonography of the eye is a simple investigation that is performed to diagnose different eye pathologies with high sensitivity, specificity, and accuracy. There are different types, techniques, and methods to perform ultrasonography of an eye. It can be done in an emergency or normal outpatient setting depending on the indication. It is like any other regular ultrasound sonography done on other parts of the body. There are currently two types of ultrasound sonography of eyes.

A-scan:

Also known as amplitude scan, this uses comparatively higher frequencies than B-scan. It is used widely to measure the axial length of the eye. There are three techniques to perform A-scan, i.e., contact method, immersion method, and automatic method. The information from the A-scan can be determined by the spike generated by the machine and by studying its height, regularity, reflectivity, and sound attenuation. It is also a part of optic biometry, an automated approach to studying the anatomical structure of an eye.

B-scan:

Also known as a brightness scan, this uses lower frequencies of ultrasound waves. There are two techniques to perform B-scan, i.e., contact method and immersion method. B-scan can visualize the eye in different planes by placing the probe accordingly. The echoes reflected are present as dots of varying intensities represented.

What Are the Indications of A-Scan (Amplitude Scan)?

The thought of an A-scan may trigger distress in someone as they may think of the transducers touching their naked eye. But as A-scan is done only after the eyes get anesthetized with anesthetic drops, patients feel minimal discomfort. A-scan gives information regarding the following features:

Length of the eye
Intraocular lens power
Lens thickness
Anterior chamber depth

By studying the characteristics of spikes generated during an A-scan, it helps plan cataract surgeries by giving estimates of correct lens implant and location of placement. It can also determine any internal tumor structures.

What Are the Indications of B-Scan (Brightness Scan)?

B-scan is one of the most convenient investigations to perform in any setting. A doctor may suggest B-scan when someone presents with ocular trauma, sudden vision changes, or signs of increased intracranial pressure. Eye conditions that can be diagnosed using B-scan are: Ocular foreign body Lens dislocation Retinal detachment Vitreous detachment Vitreous hemorrhage Retinoblastoma Pseudotumor Dense cataracts Globe rupture Choroidal melanoma Asteroid hyalosis By studying the intensities of the echoes generated during the B-scan, the above conditions can be detected. B-scan also provides the details of the shape, mobility, extension, and thickness of the structures in the eye.

What Can You Expect While Undergoing Ultrasonography of The Eye?

The concept of ultrasonography of the eye may horrify someone as they may think of the probe in the eyeball. This depends on what type of scan and what technique the examiner is using to conduct the test. The tear film is enough for effective acoustic transmission of ultrasound waves from the transducer to the eye. However, in some instances, like in ocular trauma or non-compliant patients, transducers can be placed over the eyelids with coupling jelly. It helps to glide the ultrasound probe or the transducer against the eyelid or the cornea.

1. There are ultrasound probes or transducers that come in different sizes. The transducer for A-scan is comparatively smaller than that of the B-scan. However, all the transducers are usually small, not exceeding the diameters of the anterior surface of the eye.

2. The contact method of scanning can be done in a sitting or supine position, while the immersion method is always done in the supine position. Normal saline is used in the immersion method to reduce an error due to applanation during the contact method.

3. You may be asked to move your eyeball in a different direction or to remain static. Do alert the examiner if you experience any inconvenience.

Easy to perform in any setting

Detects many ailments despite media opacity

High accuracy and reliability

High sensitivity and specificity

Painless

Free of radiation hazard

What Are the Limitations of Ultrasonography of the Eye?

Although ultrasound sonography of the eye is an easy and convenient investigation, it has a few limitations. Some of them are as follows:

Issues with patient compliance may cause corneal injuries post-procedure due to lack of sensation in the anesthetized eye
May miss minute retinal detachments and small hemorrhages
Ocular injuries or globe rupture may be further hampered
Subjective examiner interpretation may result in an error

The Takeaway

Ultrasound sonography of the eyes is a widely used tool to detect pathological eye conditions. There are two types of eye ultrasound, A-scan and B-scan. These two different types of ultrasound investigations have unique components and unique determinants to interpret the report. Eye ultrasonography is used not only as a diagnostic tool but also for monitoring post-operative patients.

Wanna know your Ultrasound Sonography of Eyes options?

Our cataract surgeon in New York has extensive training and experience in laser cataract surgery to help you regain clearer vision and start your journey to a higher quality of life.