Ultrasound uses high frequency sound waves to produce images of the internal eye structure. It is a helpful tool if cataract or vitreous clouding prevents a doctor from viewing the structures inside of your eye with traditional methods. A-scan and B-scan are two types of ultrasound tests. A-scan ultrasonography is used to measure the length from the cornea to the retina. B-scan ultrasonography is used to provide cross-sectional two-dimensional images of the inner eye.
Ultrasound is helpful for diagnosing retinal detachment, vitreous bleeding, tumors, inflammation, lesions in the eye socket bone, or foreign bodies in the eye. A-scan measurements are a factor used for selecting an artificial lens implant for cataract surgery. A-scan ultrasonography is also used to identify types of tumors in the eye.
You should arrange to have another person drive you home from your test. Following the procedure, you should not rub or touch your eyes for 30 minutes. There are no other special preparations for ultrasound examination.
Ultrasound is a quick and painless procedure. It is performed in your doctor’s office. For an A-Scan, your doctor will numb your eye with eye drops. A small transducer device is placed on your eye. The transducer transmits sound waves to a computer that produces images of the structures inside your eye. A B-scan is done through the closed eyelids and requires no preparation.
You will be asked to look straight ahead during the A-scan ultrasound. You will be instructed to look in various directions during the B-scan ultrasound. This allows your doctor to view your inner eye from different angles.
The anesthesia (numbing agent) in your eye should wear off about 15 minutes after your test. You should avoid rubbing or touching your eyes for 30 minutes following your test. This is necessary to avoid scratching your cornea.