Can ultrasound also be used for eye examinations?

Ultrasound is a non-invasive examination technology that uses the physical principles of ultrasound to obtain structural and functional information of human body tissues. Through ultrasound examination, doctors can have a more comprehensive understanding of the patient's condition and help with diagnosis and treatment. In life, we know that ultrasound examinations include gynecological ultrasound, cardiac ultrasound, abdominal ultrasound, etc. These ultrasound examinations play a vital role in clinical diagnosis, helping doctors discover diseases, evaluate organ function, and guide the formulation of treatment plans. In addition to these, did you know that ultrasound can also be used for ophthalmic examinations? Let's take you to learn about it today!

Principles of Ultrasonic Technology:

Generation and propagation of ultrasonic waves: Ultrasonic waves are high-frequency sound waves, with frequencies usually between 1 and 25 MHz. Ultrasonic waves are generated by ultrasonic transmitters, which are made of materials such as piezoelectric crystals or piezoelectric ceramics. When voltage is applied to the piezoelectric crystal, it produces mechanical vibrations and generates ultrasonic waves. Ultrasonic waves propagate through liquid or solid media, and the propagation speed is related to the density and compressibility of the medium.

Interaction between ultrasound and tissue: When ultrasound encounters a tissue interface, part of the energy will be reflected back, and part of the energy will be absorbed and scattered. The intensity and time delay of the reflection depend on the difference in acoustic impedance of the tissues on both sides of the interface. The greater the difference in acoustic impedance, the greater the reflected energy. Different tissues and organs have different acoustic impedances, so they will produce different degrees of reflection.

Echo signal reception and processing: The receiver behind the ultrasonic transmitter will receive the reflected echo signal, and the receiver will transmit the echo signal to the ultrasonic instrument for processing and analysis. The ultrasonic instrument measures the intensity and time delay of the echo, and then converts it into images or sounds.

Image generation: By processing and analyzing echo signals, ultrasound instruments can generate images of human organs and tissues. These images are presented in grayscale, with different brightness representing the acoustic impedance differences of different tissues or organs. By adjusting the frequency, power and scanning method of ultrasound, images of different depths and angles can be obtained.

Applications of ocular ultrasound technology :

Diagnosis of eye and retinal diseases: Ocular ultrasound technology can help doctors evaluate the shape, size, structure and fundus of the eye, and has important clinical significance for the early diagnosis of eye tumors, retinal detachment, abnormal intraocular pressure and other diseases.

Anterior segment disease diagnosis: Ocular ultrasound technology can be used to evaluate abnormalities in the anterior segment structure and tissue, such as glaucoma, cataracts, etc. Through ultrasound scanning, doctors can detect and evaluate lesions in a timely manner in order to develop better treatment plans.

Visual function assessment: Ocular ultrasound technology can detect visual function, including abnormalities of the optic nerve and visual pathway. This is particularly important for patients with neurological visual disorders and visual impairments, and can help doctors more accurately assess the extent of the disease and develop effective treatment plans.

Preoperative evaluation and intraoperative monitoring: Ocular ultrasound technology can help with evaluation and monitoring before and after ophthalmic surgery, such as eye measurement before cataract surgery, positioning navigation during vitreous surgery, etc. This helps improve the safety and accuracy of surgery.

Type A ultrasound:

In 1956, American ophthalmologists Mundt and Hughes first applied A-scan ultrasound to the diagnosis of eye diseases. A-scan ultrasound uses the differences in the propagation speed and echo characteristics of ultrasound in different tissues to measure the biological parameters of related tissues, and displays them in the form of wave peaks according to the echoes of different interfaces. In the field of ophthalmology, A-scan ultrasound is mainly used to measure the size and thickness of eye structures, and the measurement accuracy of corneal thickness can reach 0.001 mm. In clinical applications, A-scan ultrasound can be used for single-point or multi-point measurements, and can also be measured in concentric circles around the center point.

B-mode ultrasound:

B-scan ultrasound converts the interface echo of tissues into echo points of different brightness through sector or linear array scanning to reflect the changes in tissue structure. In ophthalmic diseases, B-ultrasound is often used for the diagnosis and treatment of ocular diseases because the eyeball and its contents have good sound transmission properties to B-ultrasound. In clinical B-ultrasound examination, the patient needs to close his eyes, lie on his back on the hospital bed, apply a special coupling agent to the eyelids, and then the B-ultrasound probe can perform a comprehensive examination of the eyes in the vertical and horizontal planes to determine the location of the lesion and measure its length, and then the printer can print out the image. B-ultrasound can be widely used in the field of ophthalmology for the diagnosis and treatment of diseases such as lens opacity, vitreous opacity, retinal detachment, and intraocular foreign bodies.

Doppler ultrasound:

It can directly observe the dynamics of blood flow in the orbit and eyeball wall, help doctors determine the mixed blood flow of arteries, veins and arteriovenous intersections, and help observe changes in the internal environment of eye cells and determine the location of tumors. Compared with general ultrasound examinations, color Doppler ultrasound is simpler and more intuitive, causes less pain to patients, and can clearly locate the target, so it has become one of the routine ophthalmic examination methods.

As a rapidly developing ophthalmic diagnostic and treatment tool, ocular ultrasound technology has great potential and broad prospects. It should be noted that ocular ultrasound examinations require professional equipment and experienced ophthalmologists. Therefore, before undergoing an ocular ultrasound examination, be sure to consult a doctor and receive professional guidance. (Gao Yanmin, Lingshou County People's Hospital, Shijiazhuang City, Hebei Province)