Very high-frequency digital ultrasound
What is it for?
Ultrasound is used to provide extremely precise measurements of the front surface of the eye (cornea and epithelium) as well as structures inside the eye (iris, ciliary body, and crystalline lens).
What actually happens?
Very high-frequency digital ultrasound (VHFU) with the ArcScan Insight 100 imaging takes approximately 3-5 minutes. While sitting, you will lean forward and rest your head on a chin-rest, as with most eye tests. The eye is then placed against a soft goggle (like a swimming goggle) which is then filled with saline solution.
While you are looking at a fixation light, the ultrasound device, without touching the eye, scans in front of the eye. The soundwaves produce a detailed cross-sectional image of the cornea and structures inside the eye.
How does it feel?
The surface of the eye is anesthetized before the exam with an eye drop. The eye is then gently rested in a “water bath” which can initially feel a little cool.
There is no other sensation throughout the exam. Most patients describe the experience as soothing.
How does it benefit you?
VHFU is the most accurate way of measuring most internal structures of the eye, particularly the cornea and structures behind the iris.
Before surgery VHFU allows for earlier diagnosis of conditions that can affect the outcome and safety of corneal refractive surgery. For example, micronic changes to the epithelial cells (front layer of skin on the cornea) can be detected using VHFU that can indicate the first signs of keratoconus (a corneal condition in which modifications to the standard corneal laser refractive surgery, or other options, must be made).
After surgery VHFU allows for the most accurate monitoring of the healing response as well as improved decision making and management of further care.
VHFU is also used in phakic IOL surgery, such as ICL sizing.
VHFU is the most accurate way to measure the structures inside the eye that affect the outcome of surgery, particularly the parts of the eye behind the iris that can only be imaged by ultrasound.
The high-resolution imaging accurately measures specific landmarks inside the eye including the sulcus, ciliary body, and crystalline lens position. Accurate measurements of these structures can help better predict the final position of the phakic IOL and therefore decrease the risk of complications (see phakic IOL section).