Ocular coherence tomography is useful for detecting and monitoring glaucoma; however, ultrasound biomicroscopes can reveal more in-depth clinical information.
“The UBM is very high resolution. It gives you a clear image and actually goes deeper than OCT,” John A. McCall Jr., OD, Primary Care Optometry News Editorial Board member, said in an interview with PCON. “It allows you to see the cornea, the iris, the angle of the anterior chamber. As a matter of fact, you can image the entire anterior chamber with this instrument.
“You can actually visualize the ciliary body, so if the patient has a ciliary cyst or a malfunctioning or malformed ciliary body, you can see that,” he continued.
John A. McCall Jr.
McCall uses the Aviso (Quantel) ultrasound biomicroscope (UBM) in his practice.
“Similar to how OCT has improved how we are able to image the macula and retinal nerve fiber layer at the cellular level, UBM provides imaging behind the iris, into the ciliary sulcus, the ciliary body, lens, angle and trabecular meshwork,” Randall F. Fuerst, OD, FAAO, who also uses Quantel’s instrument, said in an interview with PCON. “Recent advances in this technology have made it smaller, easier to use and more powerful, on top of the amazing image clarity.
“Imaging the angle provides almost definitive assessment as to whether anatomically narrowing angle closure is occurring, whether pigmentation is appearing in the trabecular meshwork, lenticular changes inducing phakolytic glaucoma, along with other difficult-to-diagnose conditions such as cystic or tumor formation in the angular structures,” he continued. “It can be extremely instructive when visual acuity has dropped and differential diagnosis is needed when assessing how much of the drop is associated with cataract formation as compared to corneal distortion or macular degenerative changes.”
“I use it a lot for phacomorphic glaucoma,” McCall said. “If a patient has a nuclear sclerotic cataract that is expanding, and the lens is expanding and closing off the angle, the patient has to be watched very closely. As the angle closes, the pressure shoots up, and the patient will fall into phacomorphic glaucoma. It will go away once the cataract is removed, but he or she needs to be monitored closely until that happens. And UBM is a great way to do that.”
UBM is reimbursable under a number of anterior segment disease codes, Fuerst said.
“The CPT 76513 (ophthalmic ultrasound, diagnostic; anterior segment ultrasound [immersion] water bath B-scan; or high-resolution biomicroscopy) describes this service,” Fuerst said. “It is paid as a ‘per eye’ service, so the ‘R’ and ‘L’ modifiers are necessary.”
This UBM image shows a tumor behind the iris that is causing narrowing of the angle.
McCall added: “The Aviso has the highest return on investment of any instrument in my practice and any instrument that I know.”
Another benefit of using the UBM, according to PCON Editorial Board member J. James Thimons, OD, is that other tests — gonioscopy, for example — are not exclusionary for reimbursement on same-day visits.
“Gonioscopy and UBM can be performed on the same day because they provide complementary information,” Thimons said in an interview. “Sometimes it’s very helpful to perform gonioscopy and assess the angle in a light-simulated situation, then do the UBM in total darkness, which is the only way to see the difference in the anatomy.
“As a result, it becomes very helpful in identifying the contribution of mixed-mechanism glaucoma, where you have both open and narrow angle disease simultaneously,” he continued. “Many patients start with open angle glaucoma and then, over time, develop the phacomorphic component, which narrows off the angle. This is an eye that’s much more difficult to manage and requires a more detailed diagnostic assessment.”