What type of ultrasound is primarily used to measure the axial length of the eye?

A-scan ultrasound is the primary type of ultrasound used to measure the axial length of the eye. This technique involves sending ultrasonic waves into the eye and measuring the time it takes for these waves to travel to the retina and back. The axial length measurement is critical for various ophthalmic assessments, especially for determining the correct power of intraocular lenses prior to cataract surgery.

In an A-scan, the output can be displayed in a one-dimensional format with peaks corresponding to different interfaces within the eye, allowing the sonographer to identify the anterior surface of the cornea, the lens, and the retina. This visual representation enables accurate measurements necessary for diagnosing and planning treatment for retinal and other ocular conditions.

B-scan ultrasound, while useful for imaging the eye’s structures and identifying abnormalities, is not specifically designed for axial length measurement. C-scan ultrasound is not a standard term used in ophthalmology, and echocardiography is entirely focused on cardiac imaging, which is unrelated to ocular measurements. Therefore, A-scan ultrasound stands out as the most appropriate choice in this context.