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Two clinicians use UBM for specific types of glaucoma management
One delegates most image capturing to a technician, while the other prefers administering the test himself to optimize its interactivity.
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Ultrasound biomicroscopy is becoming more commonly used in the optometric practice to diagnose all types of glaucoma.
Two clinicians spoke to Primary Care Optometry News regarding how they use this technology in their practice and, specifically, how they administer the test.
PCON Editorial Board member J. James Thimons, OD, FAAO, said he has been using ultrasound biomicroscopy (UBM) to diagnose narrow-angle, suspected narrow-angle and mixed-mechanism glaucoma for 3 years. He also uses it to determine placement and wound healing for surgically implanted stents, tubes and other devices.
He considers it an indispensable technology for his practice.
“High-density anterior segment optical coherence tomography (OCT) is capable of visualizing the cornea and even, to some degree, the angle,” Thimons told PCON. “However, OCT is limited by the depth that it can penetrate into the eye and, because of this limitation, it can’t provide all the information we need to accurately diagnose and subsequently manage complex, or even moderately complex, glaucoma.”
J. James Thimons
He noted that when using light instruments, such as slit lamp and gonioscopy, the angle can be altered by the combination of room light and slit-lamp illumination.
Thimons shared a recent case of a patient with low hyperopic refraction and mildly elevated intraocular pressure who looked minimally narrow on slit-lamp examination analysis. Gonioscopy showed appositional touch in the superior angle only.
In a dark room, the UBM showed that the patient’s angle was 70% closed.
“This allowed me to identify that she had a form of narrow-angle glaucoma that was amenable to peripheral iridotomy, and not primary open-angle glaucoma,” Thimons said. “Following the procedure, UBM showed significant deepening of the angle and a lowering of IOP into the normal range.”
Technician performs testing
Thimons said that his technician, Joshua Escalera, primarily performs the UBM testing.
“I have found him to be quite skilled at doing a four-plane analysis of the anterior chamber and capturing the images that are pertinent to each individual case,” he said. “Occasionally I will be in the exam room while he is taking the images to assess a unique problem that requires real-time analysis. In those cases, I will use the foot pedal to freeze and store the images I like into the computer for later review. Allowing him to perform the test while I watch frees my time to focus on anatomy and amplifies my ability to truly analyze the data.”
Thimons said that having technicians perform testing saves the clinician time that can be given back to the patient.
“As practitioners move toward a more advanced medical model of practice, the goal is to effectively assess and treat as many patients as is reasonable and prudent in the course the day,” Thimons said. “If the doctor is doing most of the testing, he or she is limiting the number of patients being seen and the efficiency of his or her interface with the patient.
“I have chosen to extend and maximize my time by employing talented staff and moving them into a position of responsibility to utilize diagnostic equipment, acquire data and subsequently work with me in the disposition of the patient by setting appointments and instructing them on medical therapy,” he continued. “This has proven to be a an ideal way to maximize my time in that it gives me the opportunity to interact with patients in the exam room, finalizing the diagnostic and therapeutic plan, instead of tied up running routine tests.”
Thimons emphasized the importance of evaluating a specific technology’s impact on your unique patient base, how you will implement it and whether it will complement existing systems.
Elliot M. Kirstein, OD, FAAO, has also been using the UBM for more than 3 years for diagnosing and managing glaucoma.
He said that like most ophthalmic diseases, glaucoma requires high-quality imaging for accurate diagnosis and treatment.
“UBM offers knowledge of the anterior chamber and a sensitivity that might otherwise be lacking in other imaging modalities,” he said.
Kirstein said the technology allows the user to differentiate between narrow-angle glaucoma, plateau iris glaucoma and pigment dispersion syndrome.
“It also determines if there is a small, shallow chamber or a large gaping chamber, which is important in monitoring IOP, as it gives us the most complete and useful perspective of anterior segment anatomy,” he said.
Elliott M. Kirstein
Kirstin said he uses the gonioscopy lens just as often, but has a better understanding of what he sees when considered in conjunction with the UBM view.
Clinician performs testing
Kirstein said he prefers performing the UBM himself as opposed to delegating the task to a technician.
“With other technologies, such as OCT, technicians follow certain parameters and take images based on those parameters,” he said. “The images that I receive and analyze from those tests are no different or even better than if I had administered the test myself.
“In the case of UBM, testing requires a more objective and interactive method of capturing images,” Kirstein said.
He said he may want to visualize a certain part of the angle, for example, and he can gather useful information while the test is being performed. Kirstein feels that, otherwise, important information may be overlooked.
Kirstein’s patients are first given topical anesthesia and viscous lubricating drops.
“If possible, we prefer to use Tetravisc Forte (tetracaine 0.5%, Cynacon/OcuSoft), which conveniently combines anesthesia and a viscosity agent in a single drop,” he said. “The patient is then instructed to lean their head back against the examination chair head rest and to fixate at a high point across the room, such as the intersection between the wall and the ceiling.
“Next, the patient is told that their eye will experience ‘a cool feeling’ as their images are being captured,” Kirstein continued.
Images are taken in four to six planes and often in different positions of gaze, he said. Rotation of the probe allows optimal visualization of superior, inferior and nasal segments of the angle.
“The variety of images might help us visualize the relative similarity in angle anatomy around the clock in a normal chamber as opposed to dramatic variations, which can be seen in anomalies such as angle closure or recession,” Kirstein said. “Checking the patency of peripheral iridectomies can also be accomplished with this procedure.”
Kirstein said his practice performs UBM testing on nearly 98% of glaucoma patients and glaucoma suspects within the first, second or third visits, with continued testing annually. – by Nancy Hemphill, ELS