June-July 2020


Skill Focus
Gonioscopy 101: Utilizations in the clinic and OR

by Ellen Stodola Editorial Co-Director

The 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 lying in a supine position,” he said. “In the office setting, gonioscopic assessment of both eyes utilizes both hands to hold the goniolens, whereas during surgery, the non-dominant hand plays a critical role in holding the lens in place to visualize the angle structures enabling the dominant hand to perform the MIGS procedure.” Dr. Shareef recommends all cataract surgeons use a fixation ring during surgery to get used to holding the handle with the non-dominant hand before transitioning to a goniolens for MIGS.
Dr. Lehrer stressed the importance of a mentor when learning how to use gonioscopy in the office and the OR. When learning in-office gonioscopy, he said to know the angle grading systems, as well as different techniques. Dr. Lehrer offered several tips for in-office gonioscopy: 1) Both the surgeon and patient should get comfortable. 2) Rest your elbow on the table or on an elbow rest or lens box. 3) Rest your fingers holding the lens against the patient’s cheek to steady the lens.
When using a direct gonio-prism to view the nasal angle in the OR, it is important to tilt the patient’s head away from the surgeon and the microscope toward the surgeon to achieve ideal visualization. Other newer lenses, including disposable lenses, may not require positioning or tilting and may be useful in operating on other angles than the nasal quadrant.

Use in the clinic and the OR

There are key differences between using gonioscopy intraoperatively and in the office, said Robert Noecker, MD. The first is the position of the patient (upright or laying down), presenting different views. Lighting can differ between the two as well.
In the office, the physician can push on the eye a bit more and change the shape, he said. If the angle is narrow, the physician can sometimes push it open wider. The slit lamp typically provides more of a 3D view, and it’s harder to achieve that in the OR with the microscope, he explained.
In the OR, there are some tricks to manipulate the position of the patient, Dr. Noecker said. One is you can change the patient’s head position to get a better look. Another key in the OR is keeping the eye well inflated.

Types of goniolenses

There are a number of commercially available direct surgical goniolenses that vary by handle length and field of view,2 Dr. Shareef said. They are all a modification of the Swan-Jacob goniolens, and some come with adjustments to counter involuntary ocular movements, such as a flange or a fixation ring. Disposable goniolenses are also available.
Much of the choice among goniolenses is surgeon preference, Dr. Noecker said. There are a variety of options to address different issues.
Dr. Lehrer’s preferred lens for office diagnostics is the Posner lens with octagonal handle (Ocular Instruments). He described it as easy to use, clean, and manipulate for compression and tilting.
Reay Brown, MD, is working on a SecureFlex (Ocular Instruments) goniolens with a wider view. He described this as a goniolens connected to a contact lens and said it works well for MIGS procedures, especially when a wider view is critical. He wanted a wider view because he performs many OMNI Surgical System (Sight Sciences) procedures and likes to see the catheter advance in the canal to confirm that it is properly placed. “Visibility is one of the keys to all MIGS,” Dr. Brown said. “I was using the original SecureFlex and liked it; I approached the company and asked if we could work together on a design to give surgeons a wider view.” Most goniolenses give about a 90-degree view, but even that is degraded at the edges, he said. “This is fine for a single ‘classic’ iStent [Glaukos], but a wider view is helpful if you are placing two iStent injects [Glaukos] or performing an OMNI or Hydrus [Ivantis] or any of the angle procedures.” The new design gives a clear view for 120 degrees.

About the doctors

Reay Brown, MD
Atlanta Ophthalmology Associates
Atlanta, Georgia

Richard Lehrer, MD
Director of Glaucoma Services
Ohio Eye Alliance
Alliance, Ohio

Robert Noecker, MD
Ophthalmic Consultants of Connecticut
Fairfield, Connecticut

Shakeel Shareef, MD
Director of Glaucoma Service
University Hospitals Eye Institute
Case Western Reserve School of Medicine
Cleveland, Ohio


1. Alward WL. A history of gonioscopy. Optom Vis Sci. 2011;88:29–35
2. Shareef S, et al. Intra-operative gonioscopy: a key to successful angle surgery. Expert Rev Ophthalmol. 2014;9:515–527.

Relevant disclosures

: None
Lehrer: Glaukos, Ivantis
Noecker: None
Shareef: None


: reaymary@comcast.net
Lehrer: rlehrer@ohioeye.com
Noecker: noeckerrj@gmail.com
Shareef: shklshrf@gmail.com

Gonioscopy 101: Utilizations in the clinic and OR Gonioscopy 101: Utilizations in the clinic and OR
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