EyeWorld Asia-Pacific September 2020 Issue

GLAUCOMA EWAP SEPTEMBER 2020 43 Gonioscopy 101: Utilizations in the clinic and OR by Ellen Stodola Editorial Co-Director Contact information Brown: reaymary@comcast.net Lehrer: rlehrer@ohioeye.com Noecker: noeckerrj@gmail.com Shareef: shklshrf@gmail.com This article originally appeared in the June/July 2020 issue of EyeWorld . It has been slightly modified and appears here with permission from the ASCRS Ophthalmic Services Corp. T he term “gonioscopy” was coined to refer to “observation of the angle,” according to Shakeel Shareef, MD, who said he thinks all ophthalmologists should be versed in its use. 1 Advances in gonioscopy occurred with the advent of the modern slit lamp microscope more than a century ago, enabling angle examination with the patient seated upright. Why is gonioscopy essential? Though it is a low-tech instrument, Dr. Shareef said it is an essential diagnostic tool that helps determine the presence of neovascularization within the angle, such as in diabetes, or presence of angle recession, microhyphema, or a cyclodialysis cleft associated with ocular trauma, or presence of peripheral anterior synechiae associated with uveitis. “In patients presenting with narrow angles necessitating laser iridotomy, it can help monitor the effect pre- and post-laser,” he said. “In glaucoma patients who are being considered for topical medical therapy, the presence of an open angle will provide the rationale to prescribe outflow enhancing agents or consideration to perform laser trabeculoplasty. Gonioscopy is an underutilized procedure that is 100% billable during an office visit and should constitute an essential part of every eyecare provider’s skill set.” Office-based gonioscopy is essential for preoperative MIGS planning. Identification of the scleral spur serves as the “surgical landmark,” separating Schlemm’s canal-based angle surgery anteriorly via the trabecular meshwork from suprachoroidal-based surgery posteriorly via the ciliary body band, Dr. Shareef said. “If the angle is closed or significant synechiae are present, an alternate surgical procedure would need to be considered,” he explained. What can gonioscopy identify? “For those who wish to familiarize themselves with this office-based procedure, I highly recommend they visit Wallace Alward’s website gonioscopy.org, ” Dr. Shareef said. One of the challenges in performing gonioscopy, he added, is to determine whether the angle is open or not, especially in patients who present with minimal to no pigment or those who have excessive pigment present. With indentation gonioscopy, one can differentiate appositional angle closure from synechial closure, Dr. Shareef said. This is important for deciding if a patient would benefit from laser iridotomy. Additionally, in patients with plateau iris, one can observe the “double hump” sign due to the anterior displacement of the ciliary body, he said. In the office, Richard Lehrer, MD, said gonioscopy can be used to diagnose primary and secondary glaucoma (normal anatomy; narrow angles with and without synechial closure; assess risk of angle closure attack and need for lensectomy, iridotomy, or iridoplasty; and distinguish other anatomical features like pigment dispersion, pseudoexfoliation, neovascular glaucoma, or Fuchs heterochromic iridocyclitis), to correctly identify congenital anomalies (immature angle or angles with cleavage abnormalities), and to correctly identify traumatic and surgical abnormalities in the anterior segment (traumatic angle recession, haptic placement of ACIOLs, prior glaucoma procedures, or retained foreign bodies). In the laser suite or OR, it can be used to correctly identify target of laser trabeculoplasty, to correctly identify structures in the anterior segment for placement of MIGS devices, to correctly identify and complete ablative or catheterizing angle procedures, or to enhance lysis of anterior segment adhesions under direct visualization. Tips for learning gonioscopy Dr. Shareef noted that office- based gonioscopy is not a substitute for intraoperative gonioscopy. “The former utilizes slit lamp-based indirect gonioscopy with the patient sitting in an upright position, whereas the latter utilizes direct gonioscopy with the patient