Water Gonioscopy: A Technique for Intraoperative Visualization of the Anterior Chamber Angle

Abstract

Aim and objective: To describe a technique of lens-free gonioscopy that allows the anterior chamber angle to be visualized intraoperatively, without the use of a gonioscopy lens. Background: Minimally invasive glaucoma surgery (MIGS) is an increasingly popular treatment option for mild to moderate glaucoma. We describe a technique of lens-free gonioscopy that allows visualization of the anterior chamber angle without the use of a lens. This simple intraoperative technique may be used to inspect the placement of MIGS devices within the angle. Technique: To perform a water gonioscopy, the surgeon sits temporal to the eye. The patient’s head is turned 20–45° away from the surgeon, and the operating microscope is tilted 15–30° toward the surgeon. A reservoir of balanced salt solution is allowed to collect in the crater formed by the nose bridge and the bony orbital rim, external to the corneal surface. This body of liquid obliterates the cornea–air interface and hence allows visualization of the anterior chamber. In contrast to gonioscopy using a gonioscopy lens, water gonioscopy offers a lower magnification, ultra-wide field of view for angle visualization. Conclusion: Water gonioscopy is a useful technique that anterior segment surgeons might use for quick visualization of the anterior chamber angle without the need for additional equipment. Clinical significance: This is a simple technique that surgeons can use to visualize the anterior chamber angles intraoperatively. It is especially useful for MIGS that are placed within the anterior chamber angle, but this technique may also be used during other anterior segment surgeries, such as visualizing the haptics of an anterior chamber intraocular lens or checking for retained lens fragments in the anterior chamber angles.