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Ultrasound biomicroscopy an important diagnostic tool for anterior portion of posterior segment
Refinement of the UBM probe, software advancements and a proven reimbursement process are reasons to invest in the technology.
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Robert J. Noecker
In my 20 years of experience using ultrasound biomicroscopy, I have become increasingly impressed with ultrasound technology for the diagnosis and treatment of many diseases, especially glaucoma. I have found it to be an invaluable instrument in my practice because it allows me to clearly visualize areas behind the iris of the eye, such as the ciliary body processes and the lens zonules. As new advancements in system technology emerge, such as probe covers that are more comfortable to the patient, the technology becomes an increasingly valuable addition to any ophthalmic practice.
Practical applications
Ultrasound biomicroscopy (UBM) is an excellent tool for imaging the more anterior portion of the posterior segment of the eye, namely, the ciliary body, lens and posterior iris. These areas are difficult, if not impossible, to see with traditional imaging devices such as optical coherence tomography, largely because melanin blocks the transmission of the light. I have found UBM to be particularly useful for patients who are suspected of having narrow-angle glaucoma. UBM can image the front of the eye, but it takes me a step further in imaging the area behind the iris so that I can better examine the ciliary body. At this point, I can determine if the patient has typical primary angle closure or narrow angles or whether he or she has plateau iris. If UBM shows that the ciliary body is too far rotated anteriorly, I can then look for a cyst or even a tumor that may be making the angle narrow. Another condition in which UBM proves helpful is malignant glaucoma, in which the entire front of the eye rotates forward. For the evaluation of surgical devices, such as tubes, I can use UBM images to determine whether a tube was successfully implanted and if fluid is flowing through it underneath the conjunctiva.
UBM of plateau iris. The ciliary body is rotated anteriorly, resulting in significant narrowing of the angle.
UBM demonstrating a glaucoma drainage device in the anterior chamber. The tube is well positioned away from the cornea and iris.
Images: Noecker RJ
Execution
When I perform UBM in my office, I have the patient recline slightly and my technician preps the patient with an anesthetic drop in the eye that is to be examined. The probe used for UBM has evolved over the years. In the past, the physician or technician had to place a rigid cup between the eye and eyelid so that water could bathe the eye during the exam. While effective, it was a little uncomfortable for the patient. Fortunately, the technology has improved. In our practice, we use Aviso UBM (Quantel Medical), with our device probe covered by a ClearScan probe cover (ESI), a flexible, clear “skin” about the size of a large marble filled with water. The probe cover is placed directly on the eye, and the technician begins to image. I observe and instruct as the test is taking place, making sure that the right areas are examined and captured. We start by aligning the probe with the limbus, where the cornea meets the sclera. I have the patient look in different directions, capturing the 12, 6, 3 and 9 o’clock positions. We use a Mac monitor and a foot pedal that the technician taps when we get the probe into the right position to capture the video images. We can then review the exact images that I am looking for.
Advantages
I have found that there is little downside to using UBM. The reimbursement process is simple, and I am not aware of an insurance company that does not reimburse for this procedure as long as the proper protocol is followed and we are imaging for approved diseases. Patients appreciate that we are using advanced technology, and with UBM, we get images of their eyes that they have never seen. It is especially helpful when we suspect a growth near the ciliary body because with UBM we can determine if the growth is a cyst, which is usually harmless, or a tumor, which can be life threatening. We can offer our patients a more narrow differential diagnosis with this technology, saving them from worrying about whether they have a cancerous tumor. Training to use UBM has become easier over the years, and while the technician or physician must be well acquainted with the anatomy to be successful with UBM imaging, it is a straightforward endeavor to learn this procedure.
UBM is a device that every eye care practitioner should have in his or her armamentarium, especially in the area of glaucoma diagnosis and treatment. As of today, UBM is an underutilized technology in ophthalmologic diagnostic imaging, simply because it is not in every office. This technology is helpful in looking for problems that can be mysterious and unseen in the pathology behind the iris. With the refinement of the probe for patient comfort, advancing software to make the probe easier to learn and to use, and the simple and proven reimbursement process, the reasons to invest in a UBM system are increasing.