The double-mirror gonioscopic lens for surgery of the anterior chamber angle.

Intraoperative examination of the anterior chamber angle is necessary during several glaucoma procedures, including goniosynechialysis and goniotomy. Many of the available lenses for this purpose are difficult to use because they require oblique illumination and their size interferes with surgical manipulations at the limbus. We have developed a double-mirror gonioscopic lens that uses direct illumination; provides an upright image of angle structures; and has a small diameter, allowing simultaneous access to the entire limbal region. We compared our lens with the Posner goniomirror (Ocular Instruments, Bellvue, Wash) and found that it provides an equal view of angle structures. The double-mirror gonioscopic lens facilitates the intraoperative visualization of the anterior chamber angle and should allow surgeons who treat glaucoma to more accurately and safely perform angle-related procedures.