54 EyeWorld Asia-Pacific | March 2025 GLAUCOMA High-resolution cross-sectional image, temporal to nasal; note narrow angle inlets measuring 15 degrees (nasal) and 7 degrees (temporal). Source: Shakeel Shareef, MD neovascularization of the angle in patients with diabetic retinopathy; 3) aids in surgical planning of angle-based surgeries; 4) assesses for angle recession in those who have sustained ocular trauma clinically observed as a widening of the ciliary body band; 5) monitors glaucoma suspects and glaucoma patients; 6) evaluates the outflow pathway in high hyperopes who are at risk for acute angle closure; and 7) facilitates laser trabeculoplasty for the ophthalmologist to aim the laser beam and deliver targeted energy to help lower the eye pressure in patients with open angle glaucoma. Limitations Of Office-Based Gonioscopy Dr. Xu said the most inconvenient aspect of gonioscopy is it requires putting a contact lens on the patient’s eye typically prior to dilation. “This can be uncomfortable for the patient. It can be time consuming. It can be disruptive to clinical workflows,” he said. “As a clinical assessment, it is not very convenient to perform gonioscopy.” Another limitation is that there is a high degree of variability between clinicians. “It’s qualitative and not terribly reproducible, so there is also that inherent limitation of the technique,” Dr. Xu said. Regarding the Lee et al. study, of which Dr. Xu was the corresponding author, he said he and the co-authors were surprised at how few gonioscopies were performed. “Perhaps it speaks to the need for new technology, something that’s more convenient,” he said. Modern Angle Imaging In lieu of or in conjunction with manual gonioscopy, Dr. Shareef said imaging technologies like anterior segment OCT (AS-OCT) and/or ultrasound biomicroscopy (UBM) can play an important role. He offered this example: “If an asymptomatic patient has anatomically narrow or closed angles determined during an eye exam, the imaging obtained would enable the physician to educate and counsel the patient of their condition, including intervention, as it would be difficult to explain to the patient otherwise. The image demonstrating angle closure would enable a provider to offer the patient options including 1) observation if asymptomatic; 2) laser iridotomy to open the drain as a preventative measure or if symptoms warrant the drain to be opened; 3) if appropriate, the need to perform cataract surgery to anatomically open the drain. This could also be a discussion in the setting of a patent iridotomy, yet the drain remains closed, and the patient is symptomatic with elevated eye pressure that needs to be lowered.” From a diagnostic standpoint, Dr. Shareef said imaging technologies can be helpful for patients who cannot have office-based gonioscopy, such as those who have a shallow or hypotonus eye. Imaging can help identify the location and size of cyclodialysis cleft for surgical planning, for example, or angle closure in the setting of a patent iridotomy in the presence of plateau iris syndrome. “[Imaging] would enable the physician to counsel the patient to consider argon laser iridoplasty to further open the angle to enhance outflow and lower the eye pressure,” Dr. Shareef said. Dr. Xu said the anterior segment OCT for glaucoma is an active area of research. “One challenge to performing gonioscopy is that it’s qualitative. We describe the structures we can see but we can’t take a precise measurement. It becomes hard to track conditions like angle narrowing or angle closure over time,” he said. “OCT has been around for several decades, and it’s widely used in the posterior segment for measuring anatomical structures like the thickness of the retina. We and other research groups have been adapting OCT for the anterior segment as a means of more precisely quantifying the anatomical configurations of our patients. I think that is a unique strength of OCT, which nicely complements a primary weakness of gonioscopy. In addition, OCT is fast; it doesn’t take a trained clinician to perform; it’s non-contact so it’s comfortable for patients. Analysis of OCT images can also be automated using other technologies, such as artificial intelligence. In these ways, OCT may fill a clinical need for a more convenient and reproducible method to assess the angle.” Some knowledge from the research being produced with AS-OCT for angle imaging is being transferred to the clinic already. Dr. Xu said he and colleagues compared AS-OCT
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