A-scan

A-scan (Amplitude scan) is a type of ultrasound used in medical diagnosis. It provides a one-dimensional view of the tissue being examined. It is commonly used in ophthalmology to measure the length of the eye and to determine the power of an intraocular lens needed after cataract surgery.

History[edit | edit source]

The A-scan was first developed in the 1950s by ophthalmologist Dr. John Alvis. It was initially used to detect foreign bodies in the eye. Over time, its use has expanded to include the measurement of eye length and the calculation of intraocular lens power.

Procedure[edit | edit source]

During an A-scan, a small probe is placed on the closed eyelid. The probe emits ultrasound waves that pass through the eye and reflect off the various structures within. These reflections are then converted into electrical signals that are displayed as a series of peaks on a graph. Each peak corresponds to a different structure within the eye, allowing the ophthalmologist to measure the length of the eye and calculate the power of the intraocular lens needed.

Applications[edit | edit source]

In addition to its use in ophthalmology, the A-scan is also used in other areas of medicine. For example, it is used in radiology to measure the size of organs and in cardiology to measure the size of the heart and its chambers.

See also[edit | edit source]

A-scan Resources
Need Help Finding a Doctor? Need help finding a doctor or specialist anywhere in the world? Explore our world directory. WikiMD's DocFinder can assist you in locating millions of physicians.	Medical Knowledge Access the latest research - Most recent articles Ongoing trials.