A-scan ultrasound biometry commonly referred to as an A-scan (short for Amplitude scan), is a routine type of diagnostic test used in ophthalmology. The most common use of the A-scan is to determine eye length for calculation of intraocular lens power used for cataract surgery.
B-scan Ultrasonography often called B-scan offers a two-dimensional cross-sectional view of the eye as well as the orbit. A B-scan is used on the outside of the closed eyelid to view the eye. A B-scan can help accurately view other eye structures like the lens, choroid, sclera, vitreous and retina. A B-scan helps diagnose retinal detachments, vitreous haemorrhages, and certain abnormalities of the optic nerve head.